Furin and the Etiopathogenesis of UV-Induced Skin Cancer

描述（由申请人提供）：Furin是蛋白转化酶（PCs）家族中的一种蛋白质加工酶，在癌症发病中起重要作用。在这项应用中，我们建议研究furin在皮肤肿瘤发展过程中的功能，重点关注小鼠皮肤在紫外线照射后发生的早期和晚期变化。PACE4是另一种相关的PC，已被证明通过激活相关蛋白酶在小鼠肿瘤细胞侵袭中发挥作用。Furin还能够通过激活生长因子和生长因子受体（如IGF-R1）来增强人癌前细胞和癌细胞的细胞增殖。由于缺乏小鼠模型来研究furin在癌变过程中的功能，因此我们设计了一系列使用转基因小鼠的实验，以便更好地了解这一重要的PC在皮肤癌发病中的作用。我们的目的是利用过表达PCs的转基因小鼠，确定furin单独或与PACE4联合促进肿瘤发展的机制。为了达到这一效果，我们设计了两个目标：首先，我们将确定体内靶向过度表达furin是否会增强紫外线诱导的实验性皮肤癌的发展。我们将在双基因小鼠中研究PACE4和furin在体内同时过表达，以确定两者在皮肤癌变中的可能合作关系。底物特异性将在单基因（K5-PACE4和K5-Furin）和双基因小鼠（K5-PACE4/Furin）的角质细胞培养物中进行评估。这些实验将阐明furin的促增殖作用的意义，以及其促创作用是否与PACE4的主要促创功能相同或不同。此外，这个特定的目标将决定两个pc的组合是否对这些生物过程中的任何一个或两个有增强作用。其次，我们还将确定PC抑制是否会阻断转基因模型中的肿瘤生长和发育。将单基因PC转基因小鼠以及双转基因K5-Furin/PACE4与K5-PDX和K5-PC-Propeptide转基因小鼠杂交，表达竞争性PC肽抑制剂或PC生理抑制剂的cDNA，我们将确定PC抑制是否会改变紫外线致癌诱导的皮肤肿瘤的形成。公共卫生相关性：该应用程序将使用现代实验动物模型来解剖蛋白转化酶的功能，这种酶激活相关的癌症相关生物分子，在鳞状细胞癌的早期形成和生长过程中，鳞状细胞癌是人类皮肤最常见的癌症之一。这些研究将有助于确定癌症发生的机制，对癌症的早期诊断和治疗具有重要的实用价值。

DESCRIPTION (provided by applicant): Furin is a protein processing enzyme of the family of proprotein convertases (PCs), which has a significant role in cancer etiopathogenesis. In this application, we propose to investigate the function of furin during skin tumor development, focusing on the early and late changes that take place after UV exposure of the mouse skin. PACE4, another related PC, has been shown to have a role in murine tumor cell invasiveness by activating relevant proteases. Furin is also able to enhance cell proliferation in human precancerous and cancer cells by activating growth factor and growth factor receptors, such as IGF-R1. The lack of a mouse model to study the function of furin during carcinogenesis prompted us to design a series of experiments using transgenic mice to facilitate the better understanding of this prominent PC in the etiopathogenesis of skin cancer. Our objective in this proposal is to determine the mechanisms by which furin contributes to tumor development alone or in combination with PACE4 using transgenic mice overexpressing PCs. Two aims have been designed to this effect: First we will determine if the targeted in vivo overexpression of furin alone will enhance the development of experimental skin cancer induced by UV. We shall investigate the simultaneous in vivo overexpression of PACE4 and furin using bigenic mice in order to establish the possible cooperation of the 2 PCs in skin carcinogenesis. Substrate- specificity will be evaluated in keratinocyte cultures derived from monogenic (K5-PACE4 and K5-Furin) as well as from bigenic mice (K5-PACE4/Furin). These experiments will clarify the significance of furin's pro-proliferative effect and whether its pro-invasive effects are the same or different from PACE4's predominant pro-invasive function. In addition, this specific aim will determine whether the combination of both PCs have an enhancing effect on any or both of these biological processes. Second, we will also determine if PC inhibition blocks tumor growth and development in transgenic models. Crossing monogenic PC transgenic mice as well as double transgenics K5-Furin/PACE4 with K5-PDX and K5-PC-Propeptide transgenic mice expressing either the cDNA of a competitive PC peptide inhibitor or that of the physiological inhibitors of PCs, we will determine if inhibition of PCs alters the formation of skin tumors induced by UV carcinogenesis. PUBLIC HEALTH RELEVANCE: This application will use modern experimental animal models to dissect the function of proprotein convertases, enzymes that activate relevant cancer-associated biomolecules, during the early formation and growth of squamous cell carcinomas, one of the most common cancers of the human skin. The proposed studies will lead to the identification of mechanisms involved in the origination of cancer that could be of great practical value in its early diagnosis and treatment.