Modulation of ErbB Signaling

描述(由申请人提供)：该项目的总体目标是阐明ErbB信号组件的调节机制，并探索这些分子作为癌症治疗的分子靶点。Shp2蛋白酪氨酸磷酸酶(PTPase)介导ErbB诱导的ERK丝裂原活化蛋白(MAP)激活，参与细胞骨架重组和细胞运动。然而，SHP2是如何调节这些反应的还不是很清楚。已有研究表明，在表皮生长因子(EGF)刺激的细胞中，GAB1是一个关键的SHP2调节因子，并且SHP2可以激活Src和Ras，但SHP2激活Src和Ras的机制尚未明确。假设了SHP2介导的两种Src激活模型，并将在特定的目标I中对其进行评估。还将分析Src在EGF诱导的RAS和ERK激活中的作用。在特定的目标II中，将发展一种新的基因敲除的小干扰RNA(SiRNA)技术，并用于分析GAB1、Gab2和SHP2在EGF诱导的细胞反应中的作用。这些包括Src和Akt/PKB的激活，Ras-MAP激酶激活的时间调节，基因表达，paxlin去磷酸化，以及细胞的生长和转移特性。根据我们的初步观察，我们推测GAB1及其相关的Pleckstrin同源(PH)结构域是在人类癌症中对抗ErbB信号和PTEN突变的新的分子靶点。这一假说将在体外稳定的癌细胞系和肿瘤异种移植中使用多西环素诱导的诱骗结构在特定目标III中进行评估。这些研究将明确ErbB和SHP2的主要信号机制，极大地促进我们对Gab蛋白功能的理解，发现恶性信号分子干预的新靶点，并刺激针对这些信号成分的新抑制剂的进一步开发。

DESCRIPTION (provided by applicant): The overall goals of this project are to elucidate regulatory mechanisms of ErbB signaling components and to explore these molecules as molecular targets for cancer therapy. SHP2 protein tyrosine phosphatase (PTPase) mediates ErbB-induced Erk mitogen-activated protein (MAP) kinase activation and is involved in cytoskeletal reorganization and cell motility. However, how SHP2 mediates these responses is not well understood. It has been shown that Gab1 is a key SHP2 regulator in epidermal growth factor (EGF)-stimulated cells and that Src and Ras are activated by SHP2, but the mechanisms by which SHP2 activates Src and Ras have not been defined. Two models for SHP2-mediated Src activation are postulated and will be evaluated in Specific Aim I. The involvement of Src in EGF-induced Ras and Erk activation also will be analyzed. In Specific Aim II, the novel small interfering RNA (siRNA) technique for gene knockdown will be developed and used to analyze the role of Gab1, Gab2, and SHP2 in EGF-induced cellular responses. These include Src and Akt/PKB activation, temporal regulation of Ras-MAP kinase activation, gene expression, paxillin dephosphorylation, and cell growth and metastatic properties. Based on our preliminary observations, we postulate that Gab1 and related pleckstrin-homology (PH) domains are novel molecular targets for antagonizing ErbB signaling and PTEN mutation in human cancers. This hypothesis will be evaluated in Specific Aim III using doxycycline-inducible decoy constructs in stable cancer cell lines in vitro and in tumor xenografts. These studies will define a major ErbB and SHP2 signaling mechanism, greatly advance our understanding of the function of Gab proteins, uncover novel targets for molecular intervention of malignant signaling, and stimulate further development of new inhibitors targeting these signaling components for cancer treatment.