New Therapeutic Vulnerabilities for Aggressive B-Cell Lymphoma

项目摘要 双重打击淋巴瘤（DHL）和双重表达淋巴瘤（DEL）是弥漫性大淋巴瘤的侵袭性亚型， 以MYC和BCL 2的易位或扩增为特征的B细胞淋巴瘤（DLBCL） 癌基因，或分别共过表达MYC和BCL 2癌蛋白。MYC和BCL 2驱动癌细胞 生长和代谢，或分别赋予对凋亡的显著抗性。因此，DHL患者 或DEL对化疗和靶向治疗反应差，目前缺乏有效的治疗选择; 事实上，DHL和DEL目前被认为是不治之症。因此，迫切需要确定新的 治疗DHL和DEL的治疗易处理的弱点。最近，我们使用 该平台包括骨髓基质并且模拟DHL肿瘤微环境。使用这个平台 我们实施了无偏的基于活性的蛋白质组学分析、药物筛选、RNA-seq和ChIP-seq研究， 确定DHL中表现出的基本途径和目标。令人吃惊的是，这些分析表明， DHL有一个独特的超级增强子（SE）景观，其中DHL中的SE与基因相关， 控制淋巴瘤细胞的命运或致癌信号。此外，这些筛选显示DHL和DEL细胞 细胞系和原代患者样本对一般转录装置的抑制剂高度敏感。在 特别是，所有的DHL和DEL细胞都对THZ 1非常敏感，THZ 1是一种新发现的细胞周期蛋白的共价抑制剂， 依赖性激酶7（CDK 7），作为转录辅因子发挥作用，并磷酸化C-末端 RNA聚合酶-II的结构域。此外，我们对CDK 9选择性抑制剂NVP 2的研究显示， DHL和DEL细胞的存活也需要这种激酶的活性，这种激酶调节转录水平， 伸长率值得注意的是，我们的新发现已经确定CDK 7和CDK 90的功能对于 维持DHL和DEL模型中MYC的表达。我们假设MYC-，CDK 7-和CDK 9- 依赖性转录和BCL-2过表达协同驱动侵袭性表型， DHL和DEL，并且因此，CDK 7或CDK 9和BCL-2的组合抑制触发了合成 致命的恶性淋巴瘤使用我们基于细胞的平台，DHL和DEL细胞系模型，DHL 患者来源的异种移植物（PDX）和同基因小鼠DHL模型，可在我们的实验室，我们 各自的专业知识，以及我们对大量主要DHL患者样本的独特访问，我们将解决 CDK 7和CDK 9在维持DHL中的作用，我们将定义CDK 7/CDK 9 维持这种致命恶性肿瘤中致癌驱动因子的表达。最后，我们将战略性地瞄准 转录机制，并在临床前验证一种治疗策略， CDK 7、CDK 9和BCL 2作为治疗DHL和DEL的综合治疗方法。!

Project Summary Double-hit lymphoma (DHL) and double-expressing lymphoma (DEL) are aggressive subtypes of diffuse large B cell lymphoma (DLBCL) that are characterized by translocations or amplifications of both MYC and BCL2 oncogenes, or that co-overexpress MYC and BCL2 oncoproteins, respectively. MYC and BCL2 drive cancer cell growth and metabolism, or confer a marked resistance to apoptosis, respectively. Accordingly, patients with DHL or DEL respond poorly to chemotherapy and targeted therapies, and currently lack effective treatment options; indeed DHL and DEL are currently considered incurable. Thus, there is an urgent need to define new therapeutically tractable vulnerabilities for the treatment of DHL and DEL. Recently, we modeled DHL using a platform that includes bone marrow stroma and that mimics the DHL tumor microenvironment. Using this platform we implemented unbiased activity-based proteomic profiling, drug screens, RNA-seq and ChIP-seq studies to identify essential pathways and targets that are manifest in DHL. Quite strikingly, these analyses revealed that DHL have a unique super-enhancer (SE) landscape, where SE manifest in DHL are associated with genes that control the lymphoma cell fate or oncogenic signaling. Further, these screens revealed that DHL and DEL cell lines and primary patient specimens are highly sensitive to inhibitors of the general transcription apparatus. In particular, all DHL and DEL cells are exquisitely sensitive to THZ1, a newly identified covalent inhibitor of cyclin- dependent kinase 7 (CDK7) that functions as a transcriptional co-factor and that phosphorylates the C-terminal domain of RNA polymerase-II. Furthermore, our studies with a selective inhibitor of CDK9 coined NVP2 revealed that DHL and DEL cells survival also requires the activity of this kinase, which regulates transcriptional elongation. Notably our new findings have established that both CDK7 and CDK90 function are essential to maintain MYC expression in models of DHL and DEL. We hypothesize that MYC-, CDK7- and CDK9- dependent transcription and BCL-2 overexpression cooperatively drive the aggressive phenotypes of DHL and DEL and, accordingly, that combined inhibition of CDK7 or CDK9 and BCL-2 triggers synthetic lethality in these aggressive lymphomas. Using our cell-based platform, DHL and DEL cell line models, DHL patient-derived xenografts (PDX) and a syngeneic mouse DHL model that are available in our laboratories, our respective expertise, and our unique access to large numbers of primary DHL patient specimens, we will address the role of CDK7 and CDK9 in the maintenance of DHL, and we will define the mechanism by which CDK7/CDK9 sustains the expression of oncogenic drivers in this lethal malignancy. Finally, we will strategically target the transcriptional machinery and pre-clinically validate a therapeutic strategy that combines drugs that disable CDK7, CDK9 and BCL2 as a synthetic therapeutic approach to treat DHL and DEL. !