Targeting MIC shedding to revive host NKG2D-mediated immune response in prostate

描述(由申请人提供)：在前列腺癌NKG2D介导的肿瘤排斥反应中，靶向MIC脱落以恢复宿主NKG2D介导的免疫反应已在实验动物模型中得到很好的证明。在人类中，由于人类NKG2D配体，MHC I类链相关分子MICA和MICB家族(统称为MIC)的肿瘤脱落，该系统无效。强有力的证据表明，肿瘤MIC的脱落对NKG2D介导的免疫功能产生了多方面的负面影响，提示它是肿瘤逃避免疫破坏和进展的机制之一。肿瘤释放MIC的机制尚不完全清楚，尽管已有多种酶被证明参与其中。然而，这些酶功能的复杂性可能不会使使用抑制剂靶向MIC脱落用于癌症治疗的临床可行性。我们的长期目标是确定抑制MIC脱落的最佳策略，并最终利用NKG2D介导的抗肿瘤免疫作为前列腺癌和其他MIC阳性肿瘤的潜在治疗方法。在我们已完成的研究中，我们已经表明，在体内阻止MIC脱落会导致前列腺癌排斥反应。最近，我们在MIC的A3结构域上定义了一个11-AA基序(脱落基序)，它对调节MIC的脱落起关键作用，并产生了一种单链抗体(ScFv)，通过靶向脱落基序来抑制MIC的脱落。在这项建议中，我们特别假设，靶向MIC的脱落与IL-15激动剂放大NKG2D介导的免疫反应相关，可以减缓前列腺癌的进展。建议的实验重点是揭示11-AA脱落基序作为治疗靶点的机制，并评估我们的新抗体靶向MIC脱落与放大NKG2D介导的免疫反应的治疗效果。我们的具体目标是：1)阐明脱落基序调节MIC脱落的机制，并作为抑制MIC脱落的治疗靶点；2)确定肿瘤细胞表面持续刺激MIC对NK细胞NKG2D功能的影响以及IL-15激动剂在这方面的影响；3)评价抗体介导的抑制MIC脱落与IL-15激动剂联合治疗前列腺癌的作用。如果我们证明用我们的抗体联合IL-15激动剂抑制MIC的脱落可以在动物模型中成功地利用宿主抗肿瘤免疫反应，那么治疗策略可以很容易地转化为前列腺癌的临床试验。此外，该试剂还可进一步工程应用于临床。此外，由于MIC的脱落在许多恶性肿瘤中是明显的，这项拟议的研究结果将对癌症治疗具有广泛的临床意义。 公共卫生相关性：针对前列腺癌中MIC的脱落以恢复宿主NKG2D介导的免疫反应。在这项建议中，我们特别假设靶向MIC脱落与IL-15激动剂放大NKG2D介导的免疫反应相关联可以减缓前列腺癌的进展。建议的实验重点是揭示我们识别的脱落基序作为治疗靶点的机制，并评估我们的新抗体靶向MIC脱落与IL-15激动剂放大NKG2D介导的免疫反应相结合的预防和治疗效果。这项研究将阐明靶向MIC脱落的机制以及基于MIC-NKG2D的肿瘤细胞与免疫系统的动态相互作用。此外，这项拟议的研究将使用我们建立的新的双转基因动物模型来验证我们的新抗体用于前列腺癌预防和治疗的有效性。此外，由于MIC的脱落在许多恶性肿瘤中是明显的，这项拟议的研究结果将对上皮性癌症的治疗具有广泛的临床意义。

DESCRIPTION (provided by applicant): Targeting MIC Shedding to Revive Host NKG2D-mediated Immune Response in Prostate Cancer NKG2D-mediated tumor rejection has been well demonstrated in experimental animal models. In humans, the system is not effective due to tumor shedding of the human NKG2D ligands, the MHC class I chain-related family of molecules MICA and MICB (collectively termed MIC). Strong evidence has demonstrated that tumor shedding of MIC results in multiple negative effects on NKG2D-mediated immunity and suggested that it is one of the mechanisms by which tumors escape immune destruction and progress. The mechanisms by which tumors shed MIC are not fully understood, although a diverse group of enzymes have been shown to be involved. However, the functional complexity of these enzymes may not make it clinically feasible to use inhibitors to target MIC shedding for cancer therapy. Our long-term goal is to define optimal strategies to inhibit MIC shedding and ultimately to harness NKG2D-mediated anti-tumor immunity as potential therapies for prostate cancer and other MIC-positive tumors as well. In our accomplished studies, we have shown that preventing MIC shedding resulted in prostate tumor rejection in vivo. Recently we have defined an 11-aa motif (shedding motif) in the a3 domain of MIC that is critical for regulating MIC shedding and generated a single chain antibody (scFv) that inhibits MIC shedding by targeting the shedding-motif. In this proposal, we specifically hypothesize that targeting MIC shedding in association with amplification of NKG2D- mediated immune responses by IL-15 agonists can attenuate prostate cancer progression. The experimental focus of proposal is to elicit the mechanisms by which the 11-aa shedding-motif is a therapeutic target and to evaluate the therapeutic impacts of targeting MIC shedding with our novel antibody in association with amplification of NKG2D-mediated immune response. Our specific Aims are: 1) to elucidate the mechanisms by which the shedding-motif regulating MIC shedding and is a therapeutic target to inhibit MIC shedding; 2) to define the impact of persistent tumor cell surface MIC stimulation on NKG2D function in NK cells and the impact of IL-15 agonist in this context; 3) To evaluate the therapeutic impact of antibody-mediated inhibition of MIC shedding combined with IL-15 agonists in prostate tumorigenesis and progression. If we show that inhibiting MIC shedding with our antibody in combination of IL-15 agonist can successfully harness host anti- tumor immune responses in animal models, the treatment strategy can be readily translated into clinical trials for prostate cancer. In addition, the reagents can be further engineered for the clinical application. Furthermore, as shedding of MIC was evident in many malignancies, the outcomes of this proposed research will have broad clinical implications for cancer therapy. PUBLIC HEALTH RELEVANCE: Targeting MIC shedding to revive host NKG2D-mediated immune response in prostate cancer In this proposal, we specifically hypothesize that targeting MIC shedding in association with amplification of NKG2D-mediated immune responses by IL-15 agonists can attenuate prostate cancer progression. The experimental focus of proposal is to elicit the mechanisms by which our identified shedding-motif is a therapeutic target and to evaluate the preventive and therapeutic impacts of targeting MIC shedding with our novel antibody in combination with amplification of NKG2D-mediated immune response by the IL-15 agonist. The proposed study will elucidate the mechanisms of targeting MIC shedding and the MIC-NKG2D-based dynamic interaction of tumor cells with the immune systems. Moreover, this proposed study will validate the effectiveness our novel antibody for prostate cancer prevention and therapy using our generated novel double transgenic animal models. Furthermore, as shedding of MIC was evident in many malignancies, the outcomes of this proposed research will have broad clinical implications for epithelial cancer therapy.