Vascular Leukocytes Influence the Tumor Microenvironment

描述(申请人提供)：我们长期的研究是为了了解免疫抑制/促血管生成白细胞的免疫生物学，这种细胞在表型上类似树突状细胞，在人和小鼠卵巢癌中明显聚集，被称为血管白细胞(VLCs)。这项建议侧重于了解最终驱动耐受活性和VLCs(以及一般调节性DC)在肿瘤部位选择性积累的分子因素。正在进行的拨款的主要发现是：在小鼠和人类的肿瘤VLC的核中过表达特殊的富含AT的序列结合蛋白1(Satb1)，这是一种控制全基因组转录程序的主编程体17；？-catenin与Satb1的共同定位；以及通过体内Satb1沉默取消VLCs的免疫抑制表型。基于这些和其他发现，我们的中心假设是，Satb1是卵巢癌中免疫抑制活性和调节性DC/VLCs优先积累的主程序设计者。 由于对Satb1在髓系白细胞亚群中的作用几乎一无所知，我们为这些研究建立了一个新的条件基因敲除小鼠模型，开发了更好的卵巢癌遗传模型，并优化了供体内使用的沉默工具。有了这些独特的资源，我们建议将应用程序集中在以下三个具体目标上： 在特定的目标1中，我们将定义Satb1如何是卵巢癌相关VLC免疫抑制特性的主要驱动因素。 在特定的目标2中，我们将确定Satb1在卵巢癌中调节性DC/VLCs积累中的作用。 在具体目标3中，我们将建立调控卵巢癌调节性DC/VLCs中Satb1过表达的分子因素。 我们的工作将通过定义Satb1-全球组织者在该领域产生深远影响 全基因组转录程序-作为最终推动免疫抑制活性和VLCs在卵巢癌中优先积累的主调节因子，这将适用于其他致命性肿瘤中的调节性DC，并对改进免疫疗法的发展具有明显的意义。 公共卫生相关性：每年约有15,000名美国人死于卵巢上皮癌。在过去的30年里，尽管对细胞周期和肿瘤细胞突变进行了广泛的研究，但非常糟糕的5年存活率并没有改变。目前的免疫疗法很少诱导致命性上皮癌的消退，部分原因是对肿瘤诱导免疫逃避的机制了解不完全。上述目标的实现将使Satb1成为推动卵巢癌中调节性髓系白细胞免疫抑制表型和病理动员的主要调节者。这一认识将为这种毁灭性疾病的化学预防、早期发现和有效治疗提供新的机制基础，这可能适用于其他致命的上皮性肿瘤。

DESCRIPTION (provided by applicant): The long term of our studies is to understand the immunobiology of the immunosuppressive/proangiogenic leukocytes that phenotypically resemble dendritic cells and distinctively accumulate in human and mouse ovarian cancer, termed by us Vascular Leukocytes (VLCs). This proposal focuses on comprehending the molecular factors that ultimately drive the tolerogenic activity and selective accumulation of VLCs (and regulatory DCs in general) at tumor locations. Key findings for the ongoing grant have been: The overexpression of special AT-rich sequence binding protein 1 (Satb1), a master programmer controlling genome-wide transcriptional programs17, in the nuclei of tumor VLCs, in both mice and humans; the co-localization of ?-catenin with Satb1; and the abrogation of the immunosuppressive phenotype of VLCs by in vivo Satb1 silencing. Based on these and other findings, our central hypothesis is that Satb1 is the master programmer of the immunosuppressive activity and preferential accumulation of regulatory DCs/VLCs in ovarian cancer. Because virtually nothing is known about the role of Satb1 in myeloid leukocyte subsets, we have generated for these studies a novel conditional knockout mouse model, developed a better genetic model of ovarian cancer, and optimized silencing tools for in vivo use. With these unique resources in hand, we propose to focus the application on the following three specific aims: In Specific Aim 1, we will define how Satb1 is the primary driver of the immunosuppressive properties of ovarian cancer-associated VLCs. In Specific Aim 2, we will define the role of Satb1 in the accumulation of regulatory DCs/VLCs within ovarian cancer. In Specific Aim 3, we will establish the molecular factors modulating the overexpression of Satb1 in regulatory DCs/VLCs in ovarian cancer. Our work will exert a profound effect in the field by defining Satb1 - a global organizer of genome-wide transcriptional programs - as the master regulator ultimately driving the immunosuppressive activity and preferential accumulation of VLCs in ovarian cancer, which will be applicable to regulatory DCs in other lethal tumors and has obvious implications for development of improved immunotherapies. PUBLIC HEALTH RELEVANCE: Epithelial ovarian cancer kills ~15,000 Americans per year. Over the last 30 years, despite extensive research into the cell cycle and tumor cell mutations, the very poor 5- year survival rates are unchanged. Current immunotherapies rarely induce the regression of lethal epithelial cancers, due in part to an incomplete understanding of the mechanisms of tumor-induced immune evasion. The accomplishment of the proposed aims will define Satb1 as the master regulator driving the immunosuppressive phenotype and pathological mobilization of regulatory myeloid leukocytes in ovarian cancer. This understanding will provide a mechanistic rationale for new advances towards chemoprevention, early detection and effective treatment of this devastating disease, which may be applicable to other lethal epithelial tumors.