Role and Regulaton of the Human DEK Proto-Oncogene

描述（由申请人提供）：拟议的工作建立在先前资助的题为“人类DEK致癌基因的作用和调控”的研究项目之上。最初的应用主要集中在DEK在HPV阳性宫颈癌细胞中的作用，基于观察到DEK被高危的HPV E7癌基因上调。我们和其他人随后证明DEK受E2F/Rb通路控制，因此在HPV阴性癌症中也广泛过表达。自20世纪90年代初以来，人们就怀疑DEK具有致癌活性。在过去的几年里，我们第一次用器官型上皮筏培养和经典的角质细胞转化试验证明了这种活性。此外，我们报道了一种新的DEK敲除小鼠模型，该模型对化学诱导的皮肤乳头瘤的发展具有部分抗性。在此，我们建议研究DEK在头颈部鳞状细胞癌（HNSCCs）中的分子作用，该癌症患者的HPV可能呈阳性或阴性。在Aim 1中，我们将在小鼠中进行DEK功能丧失和获得的研究，以确定HNSCC发展的必要性和充分性。在Aim 2中，我们将研究新发现的DEK活性在b-连环蛋白信号传导、EMT、细胞入侵和自我更新中的调节作用。这些实验将在原代人HNSCC细胞中进行。在Aim 3中，我们将进行结构-功能研究，绘制肿瘤相关的DEK结构域，并确定核DEK相互作用因素。这一结果将为我们进一步理解分子网络提供重要的第一步，通过分子网络，这种多功能染色质拓扑调节剂激活人类细胞中的致癌信号和表型（目的2）以及小鼠的HNSCC发育（目的1）。

DESCRIPTION (provided by applicant): The proposed work builds on the previously funded research project entitled "Role and regulation of the human DEK oncogene." The original application was focused on the role of DEK in HPV positive cervical cancer cells, based on the observation that DEK was up-regulated by the high risk HPV E7 oncogene. We and others subsequently demonstrated that DEK is controlled by E2F/Rb pathways and thus also widely over-expressed in HPV negative cancers. DEK had been suspected to carry oncogenic activities since the early 1990s. In the past several years, we were able to prove such activities for the first time using organotypic epithelial raft cultures and classical keratinocyte transformation assays. Furthermore, we reported a new DEK knockout mouse model which was partially resistant to the development of chemically induced skin papillomas. Herein we propose to investigate the molecular role of DEK in head and neck squamous cell carcinoma (HNSCCs), which can be positive or negative for HPV in cancer patients. In Aim 1, we will carry out DEK loss and gain of function studies in mice to determine the requirement and sufficiency for HNSCC development. In Aim 2, we will investigate newly identified DEK activities in the regulation of b-catenin signaling, EMT, cellular invasion and self-renewal. These experiments will be performed in primary human HNSCC cells. In Aim 3, we will carry out structure-function studies to map tumor-associated DEK domains and to identify nuclear DEK-interacting factors. The results will provide an important first step in advancing our understanding of molecular networks by which this versatile chromatin topology regulator activates oncogenic signaling and phenotypes in human cells (Aim 2) and HNSCC development in mice (Aim 1). PUBLIC HEALTH RELEVANCE: DEK upregulation has been clinically noted for many human tumor types, and DEK has thus been widely referred to as an oncogene. We have published that DEK supports the initial stages of cancer development, and generated the first preclinical model systems in which therapeutic DEK targeting approaches can now be tested. These models include organotypic epithelial rafts, human xenografts and DEK knockout mice. DEK inhibition selectively targeted epithelial tumor cells: acute DEK depletion caused the death and chemosensitization of cancer cells. However, DEK depletion did not affect normal cells to the same extent, and left differentiated cells which comprise the majority of human epithelium unaffected. HNC is a devastating disease with poor survival, and new approaches to diagnose and treat this disease are urgently needed. Preliminary data herein support critical roles for DEK in HNC growth, and also invasion and thus cancer cell dissemination. Thus DEK might be targeted in advanced cancers which are responsible for the great majority of HNC-related deaths. The application determines the role of DEK in the activation of b-catenin signaling pathways which we believe are a major contributor to HNC growth and spread in the human body. We anticipate that the results of the proposed studies in HNC will have broad implications for all cancers in which DEK is overexpressed. Based upon our preliminary and published findings, we postulate that DEK will be a useful diagnostic marker, and that its targeting - perhaps in conjunction with conventional chemotherapies - will improve therapeutic outcomes at both early and late cancer stages.