Targeted STAT3 inhibition impairs MDSC mobilization and recruitment in glioblastoma

项目摘要/摘要 胶质母细胞瘤(GBM)是一种普遍存在的致命性肿瘤，其治疗标准10多年来没有改变。 不幸的是，在其他侵袭性癌症中产生持久反应的免疫疗法对 GBM。限制其疗效的一个主要障碍是髓系细胞施加的相反的免疫抑制作用。 肿瘤微环境中的衍生抑制细胞。STAT3在GBM中表达丰富，是一种 预后不良的生存指标。此外，活性STAT3(在酪氨酸705处磷酸化，P-STAT3)是 是MDSC细胞的特异性标志物，在其表型极化中起重要作用。而现有的 证据有力地证明了STAT3作为肿瘤发生的驱动力和抗癌的实用靶点的作用 治疗，STAT3在远端MDSC免疫细胞中的功能作用仍未解决。在这份提案中，我提供了 支持STAT3在多形核多形核干细胞(PMN-MDSC)中激活的初步证据 在同基因荷瘤小鼠的骨髓内，与小鼠有药物抑制作用 分子药物LLL12B大大减少了进入体循环的PMN-MDSCs的数量。这些 研究结果表明，STAT3在动员PMN-MDSCs应对肿瘤方面具有至关重要的作用 LLL12B和其他STAT3特异性抑制剂的存在，以及新的抗肿瘤作用机制。 实施多项先进技术，包括高分辨率显微镜、流式细胞仪和单细胞 细胞RNA测序，我概述了利用GBM的同基因模型进行的实验，旨在1)表征 GBM中的免疫细胞表达P-STAT3，2)决定这种激活是否发生在肿瘤的局部 或外围，以及3)确定STAT3在管理PMN-MDSC贩运方面的机械作用。我假设 靶向抑制STAT3将阻止PMN-MDSC从骨髓动员，阻止它们 不会在基底膜肿瘤内积聚。这最终将改变免疫原性的平衡，从免疫- 抑制促炎，允许免疫介导的检测和杀灭癌细胞。

Project Summary/Abstract Glioblastoma (GBM) is a universally lethal tumor for which standard of care has not changed in over 10 years. Unfortunately, immunotherapies that produce durable responses in other aggressive cancers have failed against GBM. One major obstacle limiting their efficacy is the opposing immunosuppressive actions levied by myeloid- derived suppressor cells within the tumor microenvironment. STAT3 expression is enriched in GBM, and is a negative prognostic indicator of survival. Moreover, active STAT3 (phosphorylated at tyrosine 705, P-STAT3) is a specific marker of MDSC cells, and plays an important role in their phenotypic polarization. While the existing evidence strongly justifies the role of STAT3 as a driver of tumorigenesis and practical target for anti-cancer therapy, the functional role of STAT3 in distal MDSC immune cells remains unresolved. In this proposal I provide preliminary evidence that supports that STAT3 is activated in polymorphonuclear MDSC (PMN-MDSC) cells within the bone marrow of tumor bearing syngeneic mice, and that pharmacologic inhibition with the small molecule drug LLL12B greatly reduces the number of PMN-MDSCs that enter systemic circulation. These findings highlight a critically important role for STAT3 in the mobilization of PMN-MDSCs in response to tumor presence, as well as a novel mechanism of anti-tumor action for LLL12B and other specific inhibitors of STAT3. Implementing a number of advanced techniques including high resolution microscopy, flow cytometry, and single cell RNA sequencing, I outline experiments utilizing syngeneic models of GBM designed to 1) characterize which immune cells within GBM express P-STAT3, 2) determine whether this activation occurs locally within the tumor or peripherally, and 3) identify the mechanistic role of STAT3 in governing PMN-MDSC trafficking. I hypothesize that targeted inhibition of STAT3 will block PMN-MDSC mobilization from the bone marrow, preventing them from accumulating within GBM tumors. This ultimately will shift the immunogenic balance from immune- suppressive to pro-inflammatory, allowing for immune mediated detection and killing of cancer cells.