Role of TIEG1 in Foxp3+Treg development and tumor progression

描述（由申请人提供）：转化科学：癌症作为一种全身性疾病（15-CA-115）：尽管肿瘤疫苗可以诱导针对肿瘤抗原的CD 4辅助细胞和CD 8细胞毒性反应，但在临床上，它们在引起肿瘤消退方面基本无效。这是因为肿瘤细胞获得了许多机制来逃避宿主的免疫监视程序。Foxp 3 + CD 4 + CD 25 + Treg介导的免疫抑制已成为肿瘤免疫逃逸的重要机制之一，也是肿瘤免疫治疗成功的主要障碍。包括前列腺癌细胞在内的大多数恶性细胞分泌大量TGF-β，并已显示通过诱导Foxp 3表达将效应T细胞转化为肿瘤抗原特异性T细胞。这种肿瘤诱导的TGFAP不仅抑制抗肿瘤效应细胞的启动和效应功能，而且形成广泛的自放大免疫抑制网络。因此，克服肿瘤诱导的扩增和从头产生TcB对于设计用于成功癌症治疗的有效免疫策略至关重要。我们已经证明了TGF-β诱导早期基因-1（TIEG 1）在TGF-β处理的CD 4 T细胞中Foxp 3转录调控中的关键作用。E3连接酶Itch介导的monoubiquitination对于核转位和TIEG 1的转录激活是必需的。然而，在瞬时过表达系统中，Itch靶向TIEG 1进行单泛素化和多泛素化。我们的初步研究表明，抑制TGF-β诱导的Foxp 3表达的IL-6可能通过多聚泛素化诱导TIEG 1的蛋白酶体降解。Tyk 2介导的TIEG 1磷酸化似乎充当TIEG 1多聚泛素化的识别信号。因此，我们假设当CD 4 T细胞被TGF-β或IL-6刺激并调节其活化和降解时，瘙痒针对TIEG 1的单泛素化和多泛素化的差异。尽管关于Foxp 3在Treg发育和功能中的作用的数据越来越多，但Foxp 3转录是如何调节的尚不清楚。我们已经鉴定了Foxp 3启动子上彼此相邻的共有NFAT和TIEG 1结合位点。由于大多数转录因子与其他紧密结合的因子协同工作，我们推测NFAT和TIEG 1在Foxp 3启动子上相互作用并调节染色质重塑和Foxp 3表达。清楚地了解在CD 4 T细胞中印记Foxp 3转录的分子组合和串扰将有助于设计策略来破坏肿瘤微环境中的TcR抑制网络。使用分泌大量TGF-β的前列腺癌TRAMP-C2细胞，我们将分析TIEG 1缺陷对Treg发育和肿瘤进展的影响。由于TIEG 1不影响胸腺中的nTreg发育，因此靶向TIEG 1是阻断TIFE从头诱导的有吸引力的策略。预期这种策略消除抑制抗肿瘤免疫应答的最有效的肿瘤特异性Tcl 3，而没有触发自身免疫的风险。 公共卫生相关性：该申请是为了响应恢复法案挑战赠款;研究领域：转化科学主题;（15-CA-115），癌症作为一种全身性疾病。这项创新性的应用提出研究TGF-β诱导早期基因-1（TIEG 1）在肿瘤细胞分泌的TGF-β诱导Foxp 3 + T细胞中的作用。从这些研究中获得的结果有望获得重要的新见解，以最大限度地提高目前的免疫方法。此外，它符合挑战赠款的精神，因为它将需要雇用新员工，特别是在密歇根州底特律，那里的失业率是全国最高的。

DESCRIPTION (provided by applicant): Translational Science: Cancer as a systemic disease (15-CA-115): Although tumor vaccines can induce CD4 helper and CD8 cytotoxic response against tumor antigens, they have been largely ineffective in causing tumor regression in the clinic. This is because the tumor cells acquire many mechanisms to evade the immune surveillance program of the host. Foxp3+CD4+CD25+Treg-mediated immune suppression has emerged as one of the crucial tumor immune evasion mechanisms and main obstacle of successful tumor immunotherapy. Most malignant cells including prostate cancer cells secret large amounts of TGF-¿ and has been shown to convert the effector T cells into tumor antigen specific Tregs by inducing Foxp3 expression. Such tumor induced Tregs not only suppress the priming and effector function of anti-tumor effector cells but also form a broad network of self-amplifying immunosuppressive network. Therefore, overcoming tumor induced expansion and de novo generation of Tregs is critically important for the design of effective immunotherapeutic strategies for successful cancer treatment. We have demonstrated a critical role of TGF-¿ inducible early gene-1 (TIEG1) in the transcriptional regulation of Foxp3 in CD4T cells treated with TGF-¿. E3 ligase Itch-mediated monoubiquitination is essential for nuclear translocation, and transcriptional activation of TIEG1. However, in transient overexpression systems Itch targets TIEG1 for both mono and polyubiquitination. Our preliminary studies suggest that IL-6 which inhibits TGF-¿ induced Foxp3 expression induces proteasomal degradation of TIEG1 possibly through polyubiquitination. Tyk2-mediated phosphorylation of TIEG1 seems to act as a recognition signal for polyubiquitination of TIEG1. Therefore, we hypothesize that Itch targets TIEG1 differentially for mono and polyubiquitination when the CD4T cells are stimulated with TGF-¿ or IL-6 and regulates its activation and degradation. Despite the growing body of data on the role of Foxp3 in Treg development and function, how Foxp3 transcription is regulated is not clear. We have identified consensus NFAT and TIEG1 binding sites adjacent to each other on Foxp3 promoter. Since, most transcription factors work cooperatively with other factors binding in close proximity we hypothesize that NFAT and TIEG1 interact on Foxp3 promoter and regulate chromatin remodeling and Foxp3 expression. A clear understanding of molecular combinations and cross-talks that imprint Foxp3 transcription in CD4T cells will aid in designing strategies to disrupt the inhibitory network of Tregs in tumor microenvironment. Using prostate cancer TRAMP-C2 cells which secrete large amount of TGF-¿, we will analyze the effect of TIEG1 deficiency on Treg development and tumor progression. Since TIEG1 does not effect nTreg development in the thymus, targeting TIEG1 is an appealing strategy to block the de novo induction of Tregs. Such a strategy is expected to eliminate most potent tumor specific Tregs that inhibit anti-tumor immune response without the risk of triggering autoimmunity. PUBLIC HEALTH RELEVANCE: The application is in response to the Recovery Act Challenge Grant; Research Area: Translational Science Topic; (15-CA-115), Cancer as a systemic disease. This innovative application proposes to study the role of TGF-¿ inducible early gene-1(TIEG1) in the induction of Foxp3+Tregs by TGF-¿ secreted from tumor cells. The results obtained from these studies are expected gain significant new insights to maximize current immunotherapeutic approaches. In addition it complies with the spirit of the Challenge Grant as it will necessitate the hiring of new employees, especially in Detroit, Michigan which suffers from the highest unemployment rate in the country.