Lyn kinase as a key regulator in the microenvironmental niche of B lymphoid tumors

利用小分子激酶抑制剂靶向B细胞受体（BCR）相关激酶，在治疗慢性淋巴细胞白血病（CLL）等B淋巴细胞恶性肿瘤方面取得了巨大进展（Hallek et al., Lancet 2018）。在常规治疗中引入这些抑制剂后，出现了令人信服的证据，表明它们的功效不仅依赖于抑制B细胞自主功能。相反，这些抑制剂的作用机制在很大程度上可以通过淋巴肿瘤微环境（TME）内不同细胞类型的调节来解释（Nguyen, Niesen, Hallek, Leukemia 2019）。最近，我们发现了一个意想不到的，有效的功能作用Lyn激酶，BCR的中心信号成分，在恶性白血病微环境的创建中（Nguyen et al., Cancer Cell 2016）。特别是，我们观察到Lyn激酶的存在对于维持造血细胞和非造血细胞的白血病支持能力都是必需的。此外，我们实验室的初步数据表明，lyn缺乏导致TME中巨噬细胞和成纤维细胞的蛋白质组学发生深刻变化。蛋白质组学分析显示，Lyn诱导的两种细胞类型的变化几乎没有重叠，这表明Lyn激活了白血病相关巨噬细胞和成纤维细胞中不同的细胞类型特异性功能途径。这个项目的中心假设是，非受体酪氨酸激酶，如Lyn，作为B细胞淋巴瘤前肿瘤微环境的中心调节剂。因此，对这些激酶在淋巴细胞TME中功能的机制理解将有助于设计改进的抗淋巴瘤治疗方法。在第一个目标中，我们将验证不同TME细胞中Lyn激酶调节网络中的转录因子等新靶点的细胞类型特异性调节。同时，我们将探索Lyn在成纤维细胞激活和诱导促癌表型中的潜在作用。在第二个目标中，我们将使用多种体外和体内遗传工具确定负责Lyn TME作用的结构信号域。在第三个目标中，我们将采用高含量、功能性排列的crispr敲除方法来识别有助于TME细胞支持癌症能力的新治疗靶点。总而言之，所提出的工作计划的总体目标是提供对蛋白激酶的tme相关功能的更深入的了解，鉴于激酶抑制剂的广泛可用性，促进临床试验中治疗应用的重新设计。

Targeting B cell receptor (BCR)-associated kinases by small molecule kinase inhibitors has generated tremendous advances of the therapy of B lymphoid malignancies such as chronic lymphocytic leukemia (CLL) (Hallek et al., Lancet 2018). Following the introduction of these inhibitors in routine therapy, compelling evidence has emerged showing that their efficacy does not only rely on the inhibition of B cell-autonomous functions. Instead, the mechanism of action of these inhibitors can be explained to a large extent by the modulation of distinct cell types within the lymphoid tumor microenvironment (TME) (Nguyen, Niesen, Hallek, Leukemia 2019).Recently, we have discovered an unexpected, potent functional role of Lyn kinase, a central signaling component of the BCR, for the creation of a pro-malignant leukemia microenvironment (Nguyen et al., Cancer Cell 2016). Particularly, we observed that the presence of Lyn kinase is required to maintain the leukemia supporting capacity of both hematopoietic and non-hematopoietic cells. Moreover, preliminary data of our laboratory suggest that Lyn-deficiency leads to profound proteomic changes in macrophages and fibroblasts in the TME. The proteomic profiling revealed little overlap of Lyn-induced changes in the two cell types, suggesting that Lyn activates distinct, cell-type specific functional pathways in leukemia-associated macrophages and fibroblasts. The central hypothesis of this project is that non-receptor tyrosine kinases such as Lyn function as central modulators of the pro-neoplastic microenvironment for B cell lymphoma. Therefore, an improved mechanistic understanding of the function of these kinases in the lymphoid TME will be useful to design improved anti-lymphoma therapies. In the first aim, we will validate the cell type-specific modulation of novel targets including transcriptional factors within the regulatory network of Lyn kinase in different TME cells. In parallel, we will explore the potential role of Lyn in fibroblast activation and induction of a cancer-promoting phenotype. In the second aim, we will determine the structural signaling domains responsible for the TME action of Lyn using diverse in vitro and in vivo genetic tools. In the third aim, we will employ a high-content, functional arrayed CRISPR-knockout approach to identify new therapeutic targets contributing to the cancer supportive capacity of TME cells. Altogether, the overall aim of the proposed working plan is to provide a deeper understanding of the TME-related functions of protein kinases, fostering the redesigning of therapeutic applications in clinical trials, given the broad availability of kinase inhibitors.