Role of p120ctn in Esophageal Cancer

描述(申请人提供)：食道癌在全球男性癌症发病率中排名第五。鉴于这些肿瘤的存活率很低，确诊时已进入晚期，而且发病率越来越高，因此了解肿瘤发生的分子机制以及参与肿瘤转移的基因变得越来越重要。我的研究将集中在连环蛋白家族成员p120ctn及其在体内外调节肿瘤发生、细胞迁移和侵袭的能力。P120ctn定义了一个与β-连环素相关的连环素蛋白家族，该家族还与E-钙粘附素结合，并在黏附连接处稳定E-钙粘附素。因此，E-钙粘蛋白和p120ctn的表达在许多细胞系中似乎是协同调节的，推测这可能是E-钙粘蛋白表达缺失并导致EMT的另一种机制。有趣的是，p120ctn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。在很大程度上，我们还不知道是什么酶直接使这些部位磷酸化，又是在什么刺激下。然而，很明显，EGFR的激活至少在Y228可以诱导p120ctn的磷酸化。此外，还存在多种p120ctn的剪接形式。我们推测，p120ctn不同的异构体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。这一假设将被以下相互关联的具体目标所追求。目的1：评价不同异构体和磷酸化突变体对细胞运动和侵袭力的影响。P120ctn在多个食道细胞系中的表达将被下调。将引入各种异构体和磷酸化缺陷突变体，并通过单层分析以及三维Matrigel和器官型培养模型来确定突变体的运动性和侵袭性。目的：了解p120ctn在肿瘤发生发展中的作用。我们将在体内和体外过表达EGFR和下调p120ctn的表达。我们将监测这些EGFR过表达、p120ctn缺失的小鼠和细胞系的食道肿瘤发生和转移。去年，美国新诊断的食道癌病例超过1.4万例，超过90%的确诊病例将死于疾病，主要是转移性病变。这些拟议的研究将为p120ctn在食道癌的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.