Role of NKG2D in immune responses to turmors

描述（由申请方提供）：NK细胞、CD 8+和其他T细胞表达的NKG 2D刺激受体识别正常细胞表达不足和各种肿瘤细胞上调的自身配体。肿瘤细胞表达NKG 2D配体使细胞对NK细胞和在某些情况下T细胞的裂解敏感。我们的中心假设是NKG 2D（部分）作为宿主肿瘤监视装置，使NK细胞和T细胞能够消除由于致癌应激而上调NKG 2D配体的非常早期的肿瘤细胞。为了解决这一假设的关键方面，我们已经产生了Nkg 2d-/-小鼠。上一个资助期的研究表明，Nkg 2d-/-小鼠在TRAMP致癌基因转基因小鼠中对高度侵袭性、早期出现的前列腺腺癌的免疫监视以及对致癌物甲基可赛林诱导的纤维肉瘤的监视中受损。我们建议在这里调查NKG 2Ds在癌症免疫监视中的作用的几个关键机制问题。具体目标1将解决NK细胞和/或T细胞是否在体内癌症模型中介导NKG 2D介导的监视。我们将使用NKG 2D敲除小鼠与NK细胞和/或T细胞缺陷小鼠相结合的遗传研究，以确定NKG 2D监测是否主要由NK细胞、T细胞或两者介导。特异性目的2将阐述NKG 2D在体内特异性抗肿瘤应答中对CD 8 T细胞的特异性作用。由于围绕NKG 2D在增强CD 8 T细胞对肿瘤应答中的作用存在争议，我们将在过继转移/肿瘤激发模型中使用来自NKG 2D敲除或野生型小鼠的确定TCR转基因T细胞，以研究CD 8 T细胞表达的NKG 2D是否增强初始增殖和功能应答、记忆细胞的形成，维持记忆阶段的功能和排斥肿瘤的能力。特定目标3将确定TRAMP肿瘤的NKG 2D依赖性监测是否发生在肿瘤起始阶段。我们的中心假设是，NKG 2D监测是NKG 2D配体上调的结果，其由作为肿瘤发生的最早屏障的途径引起。关键是要确定监测是在早期还是在后期进行。为了解决NKG 2D依赖性监视作用于肿瘤起始的最早阶段或更晚阶段的提议，我们将研究野生型或NKG 2D敲除小鼠的定时队列中的肿瘤形成，使用NKG 2D配体表达模式、组织病理学分析和免疫浸润分析作为确定监视发生的阶段及其与配体表达和免疫细胞浸润的关系的方法。这一综合性系列实验将明确测试NKG 2D在NK细胞和T细胞中的作用，它们的相互作用，NKG 2D对CD 8 T细胞应答的影响，以及NKG 2D是否作用于早期或癌前细胞而不是更晚期的肿瘤。毫无疑问，这些研究的结论将提供对NKG 2D作用的基本理解。 公共卫生相关性这项研究解决了免疫反应如何攻击癌细胞。我们正在测试一种假设，即免疫细胞表面的一种称为NKG 2D的特异性受体蛋白使这些细胞能够攻击和杀死癌细胞。初步结果表明，由于突变而缺乏这种蛋白质的动物患癌症的几率更高。然而，一些癌细胞逃脱了这种识别系统的识别。我们的研究结果将有助于指导治疗剂的设计，帮助我们的免疫系统攻击癌症。

DESCRIPTION (provided by applicant): The NKG2D stimulatory receptor, expressed by NK cells, CD8+, and other T cells, recognizes self ligands that are poorly expressed by normal cells and upregulated by various tumor cells. Expression of NKG2D ligands by tumor cells sensitizes the cells to lysis by NK cells and in some cases T cells. Our central hypothesis is that NKG2D serves (in part) as a host tumor surveillance apparatus that enables NK cells and T cells to eliminate very early stage tumor cells that upregulate NKG2D ligands as a result of oncogenic stress To address key aspects of this hypothesis, we have generated Nkg2d-/- mice. Studies in the previous funding period demonstrated that Nkg2d-/- mice are impaired in immune surveillance of a highly aggressive, early- arising form of prostate adenocarcinoma in the TRAMP oncogene-transgenic mice, and in surveillance of fibrosarcomas induced by the carcinogen methylcolanthrene. We propose here to investigate several key mechanistic issues of NKG2Ds role in cancer immune-surveillance. Specific Aim 1 will address whether NK cells and/or T cells mediate NKG2D-mediated surveillance in cancer models in vivo. We will use genetic studies combining NKG2D knockout mice with mice deficient for NK cells and/or T cells to determine whether NKG2D surveillance is primarily mediated by NK cells, T cells, or both. Specific Aim 2 will address the role of NKG2D specifically on CD8 T cells in specific antitumor responses in vivo. Because of controversy surrounding the role of NKG2D in enhancing CD8 T cell responses to tumors, we will use defined TCR transgenic T cells from NKG2D knockout or wildtype mice in an adoptive transfer/tumor challenge model, in order to address whether NKG2D expressed by CD8 T cells enhances initial proliferative and functional responses, formation of memory cells, maintenance of functionality in the memory stage and capacity to reject tumors. Specific Aim 3 will determine whether NKG2D-dependent surveillance of TRAMP tumors occurs at the stage of tumor initiation. Our central hypothesis is that NKG2D surveillance is a consequence of NKG2D ligand upregulation resulting from pathways that serve as the earliest barriers to tumorigenesis. It is critical to determine whether surveillance occurs at such an early stage, or later. To address the proposal that NKG2D-dependent surveillance acts at the earliest stages of tumor initiation, or later, we will investigate tumor formation in timed cohorts of wildtype or NKG2D knockout mice, using NKG2D ligand expression patterns, histopathology analysis, and analysis of immune infiltrates as methods to pinpoint the stage at which surveillance occurs and its relation to ligand expression and immune cell infiltration. This comprehensive series of experiments will definitively test the role of NKG2D in NK cells and T cells, their interactions, the influence of NKG2D on CD8 T cell responses, and whether NKG2D acts on early or precancerous cells as opposed to more advanced tumors. There is no doubt that the conclusions of these studies will provide fundamental understanding of NKG2Ds role. PUBLIC HEALTH RELEVANCE This research addresses how the immune response attacks cancer cells. We are testing the hypothesis that a specific receptor protein called NKG2D on the surface of immune cells enables these cells to attack and kill cancer cells. The preliminary results show that animals that lack the protein due to a mutation have a higher incidence of cancer. Yet some cancer cells escape recognition by this recognition system. The results of our results will help to guide the design of therapeutic agents that help our immune systems attack cancer.