Pathogenesis of Cancer - Role of EGF Receptor Endocytosis

受体酪氨酸激酶（RTK）驱动许多类型癌症的发展和进展。原型 RTK家族的成员，表皮生长因子受体（EGFR），在膀胱中过表达或突变， 脑癌、肠癌、结肠癌、卵巢癌、肺癌和头颈癌。EGFR已成为主要的预后标志物 和治疗靶点。然而，尽管EGFR靶向治疗在一部分癌症中取得了成功， 表达EGFR的组成型活性突变体，EGFR抑制剂在表达EGFR的癌症中没有效果。 野生型EGFR。这在很大程度上是由于对生物多样性的调节机制认识不足， 体内肿瘤中涉及EGFR的致癌信号传导网络。我们研究的长期目标是 阐明EGFR信号传导的调节机制，并随后有助于解决重要的 如何改进EGFR靶向治疗的临床问题。我们建议通过定义 EGFR信号转导机制是通过内吞作用调节的，重点是EGFR过表达的头和- 颈部鳞状细胞癌（HNSCC）为主要实验模型。 我们的研究旨在验证两个广泛的假设：1）EGFR内吞作用的失调是至关重要的， 癌细胞生长、存活和运动;和2）可以探索内吞系统以开发新的 预测/预后标志物和鉴定新的癌症治疗靶点。我们在培养细胞中的研究 近年来建立了EGFR胞吞转运关键阶段的体外工作模型。我们还 开发了在小鼠肿瘤异种移植物中体内分析EGFR活性和内吞作用的方法。我们 使用时间分辨多路质谱分析EGFR依赖性磷酸化蛋白质组 鉴定了由EGFR在内体中启动的新的推定信号通路。我们现在处于一个独特的位置， 1)阐明EGFR依赖性肿瘤模型中EGFR体内内吞运输的机制; 2）定义 参与癌细胞生长和运动的主要信号传导途径是由核内体引发的， EGFR; 3）解读EGFR内吞转运失调对肿瘤发生过程的复杂影响， 小鼠肿瘤模型;和4）测试缓慢EGFR内吞作用与EGFR内吞作用的敏感性相关的假设。 人HNSCC与治疗性EGFR抗体西妥昔单抗的结合。拟议的研究将解开多重- EGFR胞吞转运失调对信号传导影响的多面调控机制 过程中的肿瘤细胞在体外和体内，并制定战略，使用的成分EGFR/RTK 内吞机制作为癌症的预后标志物和治疗靶点。

Receptor tyrosine kinases (RTKs) drive development and progression of many types of cancer. The archetypic member of the RTK family, epidermal growth factor receptor (EGFR), is overexpressed or mutated in bladder, brain, intestinal, colon, ovarian, lung and head-and-neck cancer. EGFR has become the major prognostic marker and therapeutic target in cancer. However, despite the success of EGFR targeted therapy in a subset of cancers expressing constitutively-active mutants of EGFR, EGFR inhibitors have not been effective in cancers expressing wild-type EGFR. This is attributable in large part to insufficient mechanistic understanding of the regulation of oncogenic signaling networks involving EGFR in tumors in vivo. The long-term objective of our research is to elucidate regulatory mechanisms of EGFR signaling and subsequently contribute to addressing the important clinical question of how to improve EGFR targeted therapy. We propose to accomplish this goal by defining the mechanisms by which EGFR signaling is regulated by endocytosis focusing on EGFR overexpressing head-and- neck squamous cell carcinoma (HNSCC) as the main experimental model. Our research aims at testing two broad hypotheses: 1) dysregulation of EGFR endocytosis is critical to cancer cell growth, survival and motility; and 2) endocytic system can be explored to develop new predictive/prognostic markers and identify new cancer therapeutic targets. Our studies in cultured cells during last years established working models of key stages of EGFR endocytic trafficking in vitro. We have also developed approaches to analyze EGFR activities and endocytosis in vivo in mouse tumor xenografts. Our analysis of the EGFR-dependent phosphoproteome using time-resolved multiplexed mass-spectrometry identified new putative signaling pathways initiated by EGFR in endosomes. We are now in a unique position to 1) elucidate the mechanisms of endocytic trafficking of EGFR in vivo in EGFR-dependent tumor models; 2) define the major signaling pathways involved in growth and motility of cancer cells that are triggered by endosomal EGFR; 3) decipher the complex effects of dysregulated EGFR endocytic trafficking on tumorigenic processes in mouse tumor models; and 4) test the hypothesis that slow EGFR endocytosis correlates with the sensitivity of human HNSCC to the therapeutic EGFR antibody, cetuximab. The proposed studies will untangle the multi- faceted regulatory mechanisms underlying the impact of dysregulated EGFR endocytic trafficking on signaling processes in tumor cells in vitro and in vivo, and develop strategies for using the components of the EGFR/RTK endocytic machinery as prognostic markers and therapeutic targets in cancer.