Tissue factor regulation of receptor tyrosine kinases in glioblastoma

项目摘要 胶质母细胞瘤(GBM)是最常见的发生在成人大脑中的癌症，尽管经过多年的密集治疗 研究表明，它仍然是一种致命的疾病。改善GBM治疗的主要障碍包括癌症干细胞 (CSC)表型，一种促进肿瘤复发和治疗耐药的自我更新行为，以及 GBM的免疫抑制微环境。受体酪氨酸激酶(RTK)的激活是 与这两个过程有关。更好地理解是什么触发了RTK信令，以及它是如何引导 对于GBM的CSC表型和免疫抑制，对于改善患者的护理是必不可少的。我们的预赛 已发表的数据证实了组织因子(Tf)在GBM恶性病变中的重要性。Tf是一种蛋白质 参与凝血，但也可以结合和激活蛋白酶激活的受体2(PAR2)，a 跨膜G蛋白偶联受体，促进细胞增殖、迁移和血管生成。这 转铁蛋白诱导的过程是为了促进伤口愈合，但可以被癌症利用来增加其 恶毒。在许多癌症中，包括胶质瘤，高转铁蛋白表达与患者较差的生存相关，并且 我们最近发表的工作表明，抑制Tf可以极大地减弱GBM的侵袭性。 在我们的初步和已发表的数据中，我们发现Tf是多种RTK的上游激活因子， 包括I类(EGFR)、II类(IGFIR)、III类(PDGFFRβ)、IV类(VEGFR-2)和X类(AX1)。我们还发现，Tf起作用 Tf是GBM中CSC表型的主要贡献者。 此外，我们还发现，Tf可以上调PD-L1的表达，PD-L1是一种存在于GBM和 髓系细胞结合后可通过抑制T细胞的活性和增殖而抑制抗肿瘤免疫 细胞。然而，TF在GBM中发挥这些作用的机制仍不清楚。我们最重要的是 假设Tf通过PAR2-2促进CSC亚群，抑制抗肿瘤免疫。 介导RTKs胞内结构域的激活。在提案的第一个具体目标中，我们将 通过确定什么构成结合来研究TF刺激RTK信号转导的机制 激活RTK的伙伴复合体，并通过研究TF和PAR2在RTK激活中的详细作用。这个 第二个具体目的将集中在TF介导的RTK激活对GBM中CSC表型的作用。 第三个特定目标将研究Tf-PAR2-RTK信号在GBM免疫抑制中的作用，以及如果 治疗药物可以抑制这一过程，延长小鼠的存活时间。拟议工作的长期目标是 为了提高对转移因子如何促进恶性行为的理解，阐明了一种新的机制，即 RTK在癌症中被激活，并证明了阻断TF-PAR2信号的治疗潜力。

Project Summary Glioblastoma (GBM) is the most common cancer arising in the adult brain, yet despite years of intensive research, it remains a fatal disease. Major barriers to improving GBM treatment include the cancer stem cell (CSC) phenotype, a self-renewing behavior that facilitates tumor recurrence and therapy resistance, and the profoundly immunosuppressive microenvironment of GBM. Activation of receptor tyrosine kinases (RTKs) is implicated in both of these processes. A better understanding of what triggers RTK signaling, and how it leads to the CSC phenotype and immunosuppression in GBM, is essential for improving patient care. Our preliminary and published data have established the importance of Tissue Factor (TF) in GBM malignancy. TF is a protein involved in blood clotting, but it can also bind and activate protease-activated receptor 2 (PAR2), a transmembrane G protein-coupled receptor that promotes cell proliferation, migration, and angiogenesis. This TF-induced process exists to facilitate wound healing, but can be harnessed by cancers to increase their malignancy. In many cancers, including glioma, high TF expression correlates with worse patient survival, and our recently published work demonstrated that suppression of TF greatly attenuates the aggressiveness of GBM. In our preliminary and published data, we found that TF is an upstream activator of multiple classes of RTKs, including class I (EGFR), II (IGF-IR), III (PDGFRβ), IV (VEGFR-2), and X (Axl). We also found that TF acts through an intracellular pathway to do so, and that TF is a major contributor to the CSC phenotype in GBM. Furthermore, we found that TF can upregulate the expression of PD-L1, which is a protein found on GBM and myeloid cells that when bound can suppress antitumor immunity by inhibiting the activity and proliferation of T cells. However, the mechanisms whereby TF exerts these effects in GBM are still unclear. Our overarching hypothesis is that TF promotes CSC subpopulations, and suppresses antitumor immunity, through PAR2- mediated activation of the intracellular domain of RTKs. In the first Specific Aim of the proposal, we will investigate the mechanisms by which TF stimulates RTK signaling by determining what constitutes the binding partner complex that activates RTKs, and by examining the detailed role of TF and PAR2 in RTK activation. The second Specific Aim will focus on the role that TF-mediated RTK activation has on the CSC phenotype in GBM. The third Specific Aim will investigate the role of TF-PAR2-RTK signaling in immunosuppression in GBM, and if therapeutics can inhibit this process and prolong survival of mice. The long-term goals of the proposed work are to improve the understanding of how TF promotes malignant behavior, elucidate a new mechanism by which RTKs are activated in cancer, and to demonstrate the therapeutic potential of blocking TF-PAR2 signaling.