Analyzing Adhesion and Signaling Functions for PTPN12 in Invasive Glioma Cells

胶质母细胞瘤(GBM)是一种对所有治疗方式都具有抵抗力的恶性脑癌。这 耐药性在很大程度上是由于高侵袭性和低增殖性癌细胞群体所致。 这些肿瘤不能接受手术切除，对化疗和放射治疗也很难接受。当一个伟大的人 Deal已知癌基因、肿瘤抑制因子和其他促进GBM细胞的途径 增殖，我们对驱动GBM细胞侵袭的机制了解相对较少。 大脑微环境。因此，派的小组进行了遗传和生化 筛选调节基底膜侵袭性细胞生长的黏附和信号因子。 这些努力确定了非受体蛋白酪氨酸磷酸酶PTP-PEST/PTPN12是一种 侵袭性GBM细胞中的关键信号效应因子。在这里，我们展示了大量 支持数据显示PTP-PEST通过调节稳定性促进GBM细胞侵袭 关键的粘着斑信号蛋白，特别是Crk相关底物(P130Cas)。在……里面 特别是，我们发现在局灶性粘连中PTP-PEST介导了相互作用 在p130Cas和含有Valosin的蛋白(VCP)之间，泛素依赖的分离酶和 泛素蛋白酶体系统的关键组成部分。这些发现导致了我们的工作 假设PTP-PEST通过调节磷酸化-PEST对GBM细胞的侵袭是必不可少的。 粘着斑蛋白底物的依赖泛素化。为了检验这一假设，我们将(1) 鉴定介导PTP-PEST之间相互作用的蛋白质结构域和基序， P130Cas和VCP，以及确定这些相互作用如何调节焦点粘连 蛋白质在GBM细胞中的稳定性；(2)鉴定PTP-Pest产生的磷降解序列 P130Cas，并确定它们如何通过招募VCP和 通过蛋白酶体促进p130Cas的降解；(3)在特定位置对VCP进行基因突变 依赖磷酸化的p130Cas泛素化所需及分析细胞侵袭力 使用三维培养系统和临床前小鼠模型；以及(4) 通过p130Cas和VCP量化人类PTP-PEST信号的水平和空间模式 GBM样本和原代癌细胞培养系统。我们会将这些数据与患者相关联 存活率以及对替莫唑胺和贝伐单抗等治疗的反应。总而言之， 这些实验不仅将阐明控制GBM细胞侵袭的信号通路 但可能会导致针对侵袭细胞和阻止肿瘤进展的新策略。

Glioblastoma (GBM) is a malignant brain cancer that is resistant to all treatment modalities. This resistance is due, in large part, to a population of high invasive and low proliferative cancer cells that elude surgical resection and are refractory to chemotherapy and radiation. While a great deal is known about oncogenes, tumor suppressors, and other pathways that promote GBM cell proliferation, we understand relatively little about mechanisms that drive GBM cell invasion in the brain microenvironment. Therefore, the PI's group performed genetic and biochemical screens to identify adhesion and signaling factors that regulate invasive cell growth in GBM. These efforts identified the non-receptor protein tyrosine phosphatase PTP-PEST/PTPN12 as a critical signaling effector in invasive GBM cells. Here, we present a significant amount of supporting data showing that PTP-PEST promotes GBM cell invasion by regulating the stability of key focal adhesion signaling proteins, particularly Crk-associated substrate (p130Cas). In particular, we have discovered that PTP-PEST in focal adhesions mediates interactions between p130Cas and valosin containing protein (Vcp), a ubiquitin-dependent segregase and key component of the ubiquitin proteasome system. These findings have led to our working hypothesis that PTP-PEST is essential for GBM cell invasion by regulating the phosphorylation- dependent ubiquitination of focal adhesion protein substrates. To test this hypothesis, we will (1) characterize protein domains and motifs that mediate interactions between PTP-PEST, p130Cas, and Vcp, as well as determine how these interactions modulate focal adhesion protein stability in GBM cells; (2) identify PTP-PEST-generated phosphodegron sequences in p130Cas and determine how they regulate focal adhesion dynamics by recruiting Vcp and facilitating p130Cas degradation by the proteasome; (3) genetically mutate Vcp at specific sites required for the phosphorylation-dependent ubiquitination of p130Cas and analyze cell invasion using three-dimensional culture systems and pre-clinical mouse models of GBM; and (4) quantify levels and spatial patterns of PTP-PEST signaling via p130Cas and Vcp in human GBM samples and primary cancer cell culture systems. We will correlate these data with patient survival as well as response to therapies such as temozolomide and bevacizumab. Collectively, these experiments will not only elucidate signaling pathways that control the GBM cell invasive state, but may lead to new strategies to target invasive cells and block tumor progression.