Pathogenesis of Cancer - Role of EGF Receptor Endocytosis

表皮生长因子（EGFR）受体（EGFR）在肿瘤的发生和发展中起重要作用， 许多人类上皮癌，与预后不良相关，并已成为主要的预后 标记物和治疗靶点。阐明的生理调节 因此，EGFR是理解其致癌激活机制的关键， 削弱EGFR治疗的潜力。生长因子与EGFR的结合引发了一个复杂的 一系列信号转导过程。受体活化也通过网格蛋白包被的细胞因子引起快速内吞作用。 溶酶体中配体-受体复合物的凹陷和降解。因此，内吞运输决定了 细胞中活性EGFR的数量，以及信号传导过程的强度和持续时间。 内吞作用还在EGFR信号传导的空间和时间调节中起作用，其可能控制细胞的增殖。 动力学和信号传导过程的特定模式。然而，EGFR内吞作用的机制 并且其与正常细胞和癌细胞中的信号传导过程的交互作用仍然知之甚少。主要 本提案的目的是描述EGFR内吞作用的机制，并确定EGFR内吞作用的作用。 内吞作用在癌症的发展和进展中的作用。在本项目的上一个供资周期， 我们已经确定了控制网格蛋白介导的细胞内化的生理途径的关键蛋白质， EGFR对我们的研究还证实了EGFR信号复合物在核内体中的定位， 内吞作用对信号传导的重要性。我们开发了新的EGFR定量分析方法， 复合物在活细胞和一种新的方法的功能分析EGFR内吞作用， 高效的RNA干扰这些重要的进展使得现在可以开发一种 EGFR内吞作用如何在癌细胞中调节以及内吞过程如何 调节癌症发生。在这个项目中，我们专注于头颈癌（HNC）的分析， EGFR经常过表达，被认为是重要的治疗靶点。具体目标 主要有：1）明确EGFR通过网格蛋白包被的小凹胞吞的分子机制。这一目标将在 特别是，使用质谱分析的新方法确定泛素化在EGFR内吞作用中的作用; 2)检测新的EGFR突变体是否具有受损的内吞转运，从而改变信号传导模式 在体外HNC细胞中的表达，并在体内影响HNC异种移植物的致瘤性; 3）测试是否改变了HNC细胞的致瘤性。 调节EGFR和可能的其它致癌受体酪氨酸的内吞作用的蛋白质的表达 激酶影响体外EGFR信号传导和体内HNC异种移植物的致瘤特性。成功 该提案目标的完成将为设计治疗和预防措施开辟新的途径。 治疗EGFR表达癌症的策略。

Epidermal growth factor (EOF)receptor (EGFR) is important for the development and progression of many human epithelial cancers, associated with poor prognosis and has become the major prognostic marker and therapeutic target in a variety of these cancers. Elucidation of the physiological regulation of EGFR is, therefore, a key to understanding of the mechanisms causing its oncogenic activation and impairing the potential of EGFR therapeutics. Growth factor binding to the EGFR triggers a complicated array of signal transduction processes. Receptor activation also causes rapid endocytosis via clathrin-coated pits and degradation of the ligand-receptor complexes in lysosomes. Thus, endocytic trafficking determines the number of active EGFRs in the cell and,therefore, the intensity and duration of signaling processes. Endocytosis also plays role in spatial and temporal regulation of EGFR signaling, which may control the dynamics and the specific pattern of signaling processes. However, the mechanisms of EGFR endocytosis and its cross-talks with signaling processes in normal and cancer cells remain poorly understood. The main goal of this proposal is to delineate the mechanisms of EGFR endocytosis, and to define the role of endocytosis in the development and progression of cancer. During the previous funding cycle of this project we have identified key proteins that control the physiological pathway of clathrin-mediated internalization of EGFR. Our studies also demonstrated localization of EGFR signaling complexes in endosomes and the importance of endocytosis for signaling. We have developed novel quantitative methods of analysis of EGFR complexes in living cells and a novel methodology of the functional analysis of EGFR endocytosis using highly efficient RNA interference. These important advances make it now feasible to develop a comprehensive model of how EGFR endocytosis is regulated in cancer cells and how endocytic processes regulate cancerigenesis. In this project we focus on the analysis of head-and-neck cancer (HNC) where EGFR is frequently overexpressed and considered to be an important therapeutic target. The specific aims are: 1) Define the molecular mechanisms of EGFR endocytosis through clathrin coated pits. This aim will, in particular, define the role of ubiquitylation in EGFR endocytosis using novel methods of mass-spectrometry; 2) Test whether new EGFR mutants with impaired endocytic trafficking produce altered patterns of signaling in HNC cells in vitro and affect tumorigenic properties of HNC xenografts in vivo; 3) Test whether altered expression of proteins regulating endocytosis of EGFR and possibly other oncogenic receptor tyrosine kinases affect EGFR signaling in vitro and tumorigenic properties of HNC xenografts in vivo. The successful completion of the aims of the proposal will open new avenues to design of therapeutic and preventive strategies in treatment of EGFR expressing cancers.