Signal transduction and gene induction in lymphocytes

摘要 现代免疫疗法对临床肿瘤学产生了广泛的影响。CAR-T细胞疗法已经在 成功对抗某些血液恶性肿瘤，以及靶向PD-1/PD-1的“免疫检查点阻断”。 L1通路或其他T细胞抑制通路已被证明是晚期实体瘤的有效治疗方法 在一部分患者中。另一方面，CAR T细胞疗法对实体瘤的成功有限， 许多接受免疫检查点阻断治疗的患者要么没有反应，要么发生肿瘤。 复发限制这些治疗控制癌症能力的一个共同因素是肿瘤浸润性T细胞 细胞变得“疲惫”。我们需要在分子水平上理解免疫细胞的衰竭， 为了设计出更有效地根除原发肿瘤的治疗方法， 并促进肿瘤特异性记忆细胞的发育，以防止复发。 几年前，我们发现转录因子NFAT-经典的T细胞效应子的主要驱动因子， 反应-也启动T细胞耗竭。T细胞受体刺激与有效共刺激配对 激活NFAT及其转录伴侣AP 1，并驱动效应子应答。然而，NFAT 同时激活一个单独的细胞内在程序，抑制T细胞的反应，与相对 两个转录程序的强度取决于上下文。在肿瘤中， 程序是有利的，导致T细胞耗尽。我们最近发现了TOX和NR 4A家族的转录 因子如由NFAT诱导的基因，其与NFAT合作以促进耗竭程序。已经 认为耗竭是一个渐进的过程，但事实上，我们已经证明，TOX mRNA和TOX 蛋白质--沿着其他耗竭标志物--在肿瘤抗原特异性CD 8 + T细胞中被急剧诱导 当他们遇到肿瘤的时候。这意味着CAR T细胞或扩增的肿瘤抗原- 当特定的T细胞被注入患者体内时，它们立即处于危险之中，这也许可以解释这种要求。 用于转移大量的细胞，并部分解释了治疗的有限成功。 在这里，我们计划解决基本的转录机制控制的开始耗尽，作为一个 最终在临床上解决这个问题的背景。在目标1中，我们将定义 转录因子，并通过延伸，驱动TOX表达的细胞信号传导途径， 疲惫不堪在目标2中，我们将探讨TOX如何通过直接控制密钥来进一步实现穷举程序 耗竭特异性基因在目标3中，我们将解决一个非常实际的问题， 肿瘤浸润淋巴细胞可以通过滴定来防止或逆转衰竭， 进一步发展临床应用的原则。 我们的研究结果将有助于对基因组中关键转录机制的广泛理解。 小鼠和人肿瘤浸润性T细胞。

ABSTRACT Modern immunotherapies have had a broad impact in clinical oncology. CAR T cell therapy has been dramatically successful against certain hematologic malignancies, and ‘immune checkpoint blockade’ targeting the PD-1/PD- L1 pathway or other T cell inhibitory pathways has proven to be an effective treatment for advanced solid tumors in a subset of patients. On the other hand, CAR T cell therapy has had only limited success against solid tumors, and many patients treated with immune checkpoint blockade either do not respond or experience tumor recurrence. One shared factor limiting the ability of these treatments to control cancer is that tumor-infiltrating T cells become ‘exhausted’. We need to understand immune cell exhaustion at a molecular level, both in mouse models and in humans, in order to design therapies that will be more effective at eradicating the original tumor and in fostering the development of tumor-specific memory cells that will prevent a recurrence. We discovered some years ago that the transcription factor NFAT— classically a main driver of T cell effector responses— also initiates T cell exhaustion. T cell receptor stimulation paired with effective costimulation activates NFAT and its transcriptional partner AP1, and drives the effector response. However, NFAT simultaneously activates a separate cell-intrinsic program that damps down T cell responses, with the relative strength of the two transcriptional programs depending on the context. In tumors, the hyporesponsiveness program is favored, leading to T cell exhaustion. We recently identified TOX- and NR4A-family transcription factors as genes induced by NFAT that cooperate with NFAT to further the exhaustion program. It has been thought that exhaustion is a gradual process, but in fact we have demonstrated that TOX mRNA and TOX protein— along with other markers of exhaustion— are sharply induced in tumor antigen-specific CD8+ T cells almost immediately when they encounter a tumor. This means that CAR T cells or expanded tumor antigen- specific T cells are immediately at risk when they are infused into a patient, perhaps explaining the requirement for transferring large numbers of cells, and accounting in part for the limited success of the therapies. Here, we plan to address the fundamental transcriptional mechanisms controlling the onset of exhaustion, as a background for eventually circumventing this problem in the clinic. In Aim 1, we will define the ensemble of transcription factors and, by extension, the cellular signalling pathways that drive TOX expression and lead to exhaustion. In Aim 2, we will probe how TOX then furthers the exhaustion program by directly controlling key exhaustion-specific genes. In Aim 3, we will address the very practical question whether TOX protein levels in tumor-infiltrating lymphocytes can be titrated to prevent or reverse exhaustion, taking an approach that could in principle be developed further for clinical use. Our results will contribute to a broad mechanistic understanding of key transcriptional mechanisms operating in mouse and human tumor-infiltrating T cells.