Role of serine protease KLK7 in pancreatic cancer

描述(由申请人提供)： 胰腺癌的特征是邻近结构的局部侵犯，神经周围的侵犯，早期的淋巴结和肝脏转移，以及强烈的促结缔组织间质反应。然而，我们对这种疾病的高度侵袭性的了解严重不足。最近，我们发现激肽释放酶7(KLK7)在胰腺导管腺癌(PDAC)中过表达。通过一系列的体外实验，我们进一步证明KLK7可能直接或间接地参与促进胰腺肿瘤侵袭周围组织的过程，包括E-钙粘附素的脱落、纤维连接蛋白的裂解、与玻璃体连接蛋白的黏附丧失、桥粒芯糖蛋白-2的降解以及原基质金属蛋白酶-9的激活。在初步研究中，为了研究KLK7在胰腺肿瘤中表达的功能意义，我们利用shRNA介导的抑制KLK7的方法，在免疫缺陷小鼠皮下接种来自胰腺癌细胞系的肿瘤异种移植瘤中。KLK7的抑制导致肿瘤生长显著减少，从而提供了令人信服的证据，表明KLK7在胰腺中的异常表达在胰腺肿瘤的发生中起着重要作用。根据我们已发表的和初步的发现，我们假设KLK7在胰腺癌中的异常表达是由于启动子甲基化的改变，导致不适当地诱导蛋白分解活性，从而促进肿瘤的侵袭和转移，并促进胰腺肿瘤的生长。我们将通过以下特定目的来检验这些假说：1)通过胰腺癌实验模型检测KLK7表达抑制对胰腺肿瘤发生、生长和侵袭的影响。2)研究S调节胰腺癌KLK7表达的机制。3)检测KLK7蛋白水解酶活性在胰腺癌细胞中的下游作用。这些研究将有助于填补我们在胰腺癌中发展的非调控细胞过程的知识缺陷，这种过程会产生高度侵袭性的肿瘤和极其糟糕的患者预后，并可能为针对KLK7表达和/或其蛋白分解活性的新型治疗干预措施提供见解，从而为这种毁灭性疾病带来新的治疗方法。 公共卫生相关性： 胰腺癌是一种毁灭性的疾病，其存活率是所有实体癌症中最低的。除了吸烟，很少有危险因素显示与胰腺癌的发展有强烈和一致的联系。然而，胰腺癌的一个始终如一的危险因素是慢性胰腺炎，这是退伍军人患者群体中一个重大的健康问题。胰腺癌的特征之一是其早期全身扩散。不幸的是，人们对癌细胞如何从原发肿瘤部位分离并在远处器官中生长知之甚少。在观察到激肽释放酶7在胰腺肿瘤中过表达的基础上，我们将探讨其在胰腺癌中的作用。因此，这些研究的结果将有助于填补我们对这种毁灭性疾病的理解的空白，并可能提供新的治疗策略。

DESCRIPTION (provided by applicant): Pancreatic cancer is characterized by local invasion of adjacent structures, perineural invasion, early metastases to lymph nodes and liver, and an intense desmoplastic stromal reaction. Our understanding of the highly invasive nature of this disease, however, is severely deficient. Recently, we have made the novel finding that kallikrein 7 (KLK7) is overexpressed in pancreatic ductal adenocarcinomas (PDAC). Using a series of in vitro experiments, we have further demonstrated that KLK7 may participate both directly and indirectly in processes that facilitate the ability of pancreatic tumors to invade surrounding tissues including the shedding of E-cadherin, cleavage of fibronectin, loss of adhesion to vitronectin, degradation of desmoglein-2, and activation of proMMP-9. In preliminary studies, to examine the functional significance of KLK7 expression in pancreatic tumors, we have utilized shRNA-mediated suppression of KLK7 in tumor xenografts derived from pancreatic cancer cell lines inoculated subcutaneously in immunodeficient mice. KLK7 suppression resulted in a dramatic decrease in tumor growth; thus providing compelling evidence that aberrant expression of KLK7 in the pancreas plays an important role in pancreatic tumorigenesis. Based on our published and preliminary findings, we hypothesize that KLK7 is aberrantly expressed in pancreatic adenocarcinomas due to altered promoter methylation, which results in inappropriate induction of proteolytic activity that facilitates tumor invasion and metastasis and enhances pancreatic tumor growth. We will test these hypotheses through the following specific aims: 1) Examine the effects of suppression of KLK7 expression on pancreatic tumor development, growth, and invasion using experimental models of pancreatic cancer. 2) Examine the mechanism(s) regulating KLK7 expression in pancreatic cancer. 3) Examine downstream effects of KLK7 proteolytic activity in pancreatic cancer cells. These studies will help fill the deficits in our knowledge regarding the deregulated cellular processes that develop in pancreatic cancer that produces highly aggressive tumors and extremely poor patient outcomes and may provide insights into novel therapeutic interventions that target either KLK7 expression and/or its proteolytic activity leading to new treatments for this devastating disease. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is a devastating disease that has the lowest survival rate for any solid cancer. Other than cigarette smoking, few risk factors have shown a strong and consistent association with the development of pancreatic cancer. The one consistent risk factor for pancreatic cancer, however, is chronic pancreatitis, which is a significant health concern in the Veterans' patient population. One of the hallmarks of pancreatic cancer is its early systemic dissemination. Unfortunately, little is known about how cancer cells detach from the primary tumor site and grow in distant organs. Based on the observation that the protease kallikrein 7 is overexpressed in pancreatic tumors, we will investigate its role in pancreatic cancer. The results of these studies, therefore, will help fill the void in our understanding of this devastating disease and may provide novel treatment strategies.