Mechanism of Chaperone-Mediated Tumor Rejection

描述（由申请方提供）：用肿瘤来源的GRP 94/gp 96（内质网Hsp 90分子伴侣）接种疫苗可引起肿瘤生长和转移的抑制。GRP 94/gp 96在小鼠的预防性和治疗性疫苗接种中的显著治疗功效促使其作为用于治疗人类癌症的免疫剂的临床评价。目前，GRP 94/gp 96正在进行肾癌和黑色素瘤的III期试验。尽管GRP 94/gp 96作为一种新型免疫抑制剂引起了人们的极大兴趣，但其作用机制仍不清楚。这项研究的广泛、长期目标是确定GRP 94/gp 96介导的抗肿瘤免疫反应的机制。这一目标将在以下具体目标中实现：1.定义gp 96分泌的基于细胞的肿瘤疫苗策略的免疫学基础; 2.确定gp 96和gp 96 NTD在先天免疫应答调节中的作用。3.研究gp 96和gp 96 NTD在逆转录病毒诱导疾病的早期免疫调节中的作用。4.鉴定在gp 96/gp 96 NTD识别和细胞活化中起作用的效应细胞和效应细胞受体。 所提出的研究将利用最近开发的新型免疫策略，其中用表达分泌形式的GRP 94/gp 96的细胞对动物进行免疫接种。使用这种实验方法，我们已经证明了GRP 94/gp 96介导的肿瘤排斥反应与组织来源无关，因此GRP 94/gp 96引起的抗肿瘤免疫应答可以使用非肿瘤来源的GRP 94/gp 96引起。鉴于在这些实验中鉴定的肿瘤限制的缺乏，我们假设GRP 94/gp 96通过激活先天性免疫应答起作用。这种反应是强大的抗癌适应性免疫反应的必要先决条件。在执行上述特定目标时，我们将使用预防性和治疗性免疫策略，在多种肿瘤模型中定义gp 96分泌型、基于细胞的肿瘤疫苗策略的功效。将进行GRP 94/gp 96与先天免疫系统的效应细胞的相互作用的详细研究。这些研究将强调体内模型和体内细胞反应的分析。为了更好地定义GRP 94/gp 96与先天免疫系统相互作用的机制，我们建议将分析扩展到逆转录病毒诱导的疾病的研究，在新生儿模型中，并识别GRP 94/gp 96访问的信号通路。

DESCRIPTION (provided by applicant): Vaccination with tumor-derived GRP94/gp96, the endoplasmic reticulum Hsp90 molecular chaperone, can elicit suppression of tumor growth and metastasis. The substantial therapeutic efficacy of GRP94/gp96 in prophylactic and therapeutic vaccination of mice has prompted its clinical evaluation as an immunotherapeutic for treatment of cancer in humans. Currently, GRP94/gp96 is undergoing Phase III trials for kidney cancer and melanoma. Although GRP94/gp96 has generated substantial interest as a novel immunotherapeutic, its mechanism of action remains unknown. The broad, long-term objective of the proposed research is to identify the mechanism of GRP94/gp96-mediated anti-tumor immune responses. This objective will be accomplished in the following specific aims: 1. Define the immunological basis for a gp96-secreting, cell-based tumor vaccine strategy; 2. Determine the role of gp96 and gp96 NTD in the regulation of innate immune responses. 3. Examine the role of gp96 and gp96 NTD in early immune modulation of retrovirus-induced disease. 4. Identify the effector cells and effector cell receptor(s) functioning in gp96/gp96NTD recognition and cell activation. The proposed studies will utilize a recently developed novel immunization strategy wherein animals are vaccinated with cells expressing a secretory form of GRP94/gp96. Using this experimental approach, we have demonstrated that GRP94/gp96-mediated tumor rejection is independent of the tissue of origin and thusGRP94/gp96-elicited anti-tumor immune responses can be elicited using GRP94/gp96 of non-tumor origin. Given the absence of tumor-restriction identified in these experiments, we hypothesize that GRP94/gp96functions through activation of innate immune responses. Such responses are a necessary prerequisite to robust anti-cancer adaptive immune responses. In executing the Specific Aims presented above, we will define the efficacy of the gp96-secreting, cell-based tumor vaccine strategy in multiple tumor models, using prophylactic and therapeutic immunization strategies. Detailed studies of the interactions of GRP94/gp96 with effector cells of the innate immune system will be performed. These studies will emphasize in vivo models and analyses of in vivo cellular responses. To better define the mechanism of GRP94/gp96 interaction with the innate immune system, we propose to extend analyses to the study of retrovirus-induced disease, in a neonate model, and to identification of signaling pathways accessed by GRP94/gp96.