Role of p120ctn in Esophageal Cancer

描述（由申请方提供）：食管癌是全球男性中第五常见的癌症。鉴于生存率低，诊断时疾病的晚期和疾病的频率增加，了解这些肿瘤起始的分子机制以及参与其转移的基因越来越重要。我的研究将集中在连环蛋白家族成员p120 ctn及其在体外和体内调节肿瘤发生以及细胞迁移和侵袭的能力。p120 ctn定义了一个与β-连环蛋白相关的连环蛋白家族，其也结合E-钙粘蛋白并在粘附连接处稳定E-钙粘蛋白。因此，E-cadherin和p120 ctn的表达在许多细胞系中似乎是协同调节的，并且推测这可能是E-cadherin表达丢失并导致EMT的另一种机制。有趣的是，p120 ctn含有16个不同的磷酸化位点，8个酪氨酸和8个丝氨酸/苏氨酸。什么样的激酶直接磷酸化这些位点，以及在什么样的刺激下，在很大程度上是未知的。然而，很明显，EGFR活化可以诱导至少在Y228处的p120 ctn磷酸化。此外，p120 ctn存在许多剪接形式。我们推测p120 ctn的不同亚型和磷酸化位点可能调节其与其结合伙伴相互作用的能力，从而改变其促进肿瘤发生和转移的能力。这一假设将通过以下相互关联的具体目标来实现。目的1：评估不同亚型和磷酸化突变体对运动和侵袭性的影响。p120 ctn的表达将在几种食管细胞系中被敲低。将引入各种亚型和磷酸化缺陷突变体，并通过单层测定以及三维基质胶和器官型培养模型确定突变体的运动性和侵袭性。目的2：了解p120 ctn在肿瘤发生发展中的作用。我们将在体内和体外过表达EGFR并敲低p120 ctn表达。我们将监测这些EGFR过表达、p120 ctn缺失的小鼠和细胞系的食管肿瘤发生和转移。去年，美国诊断出超过14，000例新的食管癌病例，其中90%以上的诊断者将死于疾病，主要是转移性病变。这些研究将为p120 ctn在食管癌发生和发展中的生物学作用提供新的见解。最终，这些研究可能会转化为这种致命疾病的新诊断和治疗方式。

DESCRIPTION (provided by applicant): Esophageal cancer represents the 5th most frequent cancer in males worldwide. Given the poor survival rate, advanced stage of the disease at diagnosis and the increasing frequency of the disease it is increasingly important to understand the molecular mechanisms of initiation of these tumors as well as the genes involved in their metastasis. My research will focus on the catenin family member p120ctn and its ability to modulate tumorigenesis as well as cell migration and invasion in vitro and in vivo. p120ctn defines a family of catenin proteins related to beta-catenin that also bind to E-cadherin and stabilizes E-cadherin at adherens junctions. As a result, expression of E-cadherin and p120ctn appear to be coordinately regulated in many cell lines and it is speculated that this may be another mechanism by which E-cadherin expression may be lost and lead to EMT. Interestingly, p120ctn contains 16 different phosphorylation sites, 8 tyrosine and 8 serine/threonine. What kinases directly phosphorylate these sites and under what stimuli are largely unknown. However, it is clear that EGFR activation can induce phosphorylation of p120ctn at least at Y228. Additionally, many splice forms for p120ctn exist. We hypothesize that the different isoforms and phosphorylation sites of p120ctn may regulate its ability to interact with its binding partners and therefore alter its ability to promote tumorigenesis and metastasis. This hypothesis will be pursued by the following interrelated specific aims. Aim 1: To assess the effects different isoforms and phosphorylation mutants have on motility and invasiveness. Expression of p120ctn will be knocked-down in several esophageal cell lines. Various isoforms and phosphorylation-deficient mutants will be introduced and motility and invasiveness of the mutants will be determined through monolayer assays as well as three-dimensional Matrigel and organotypic culture models. Aim2: To understand the role of p120ctn in tumor initiation and progression. We will overexpress EGFR and knockdown p120ctn expressin in vivo and in vitro. We will monitor these EGFR-overexpressing, p120ctn-deleted mice and cell lines for esophageal tumorigenesis and metastasis. Over 14,000 new cases of esophageal cancer were diagnosed in the United States last year and more than 90% of those diagnosed will die of their disease, primarily from metastatic lesions. The proposed studies will provide novel insights into the biological roles of p120ctn in the development and progression of esophageal cancer. Ultimately, these studies may translate into new diagnostic and therapeutic modalities for this deadly disease.