New Therapeutic Vulnerabilities for Aggressive B-Cell Lymphoma

项目摘要 双重淋巴瘤(DHL)和双重表达淋巴瘤(DEL)是弥漫性大细胞淋巴瘤的侵袭性亚型 以MYC和BCL2易位或扩增为特征的B细胞淋巴瘤(DLBCL) 癌基因，或分别过度表达MYC和BCL2癌蛋白的癌基因。MYC和BCL2驱动癌细胞 生长和新陈代谢，或分别赋予对细胞凋亡的显著抵抗。因此，DHL患者 或DEL对化疗和靶向治疗反应不佳，目前缺乏有效的治疗选择； 事实上，DHL和Del目前被认为是无法治愈的。因此，迫切需要定义新的 治疗DHL和DEL的治疗上易于处理的脆弱性。最近，我们使用一个 包括骨髓基质和模拟DHL肿瘤微环境的平台。使用此平台 我们实施了基于活性的无偏见蛋白质组图谱、药物筛选、RNA-SEQ和CHIP-SEQ研究，以 确定在DHL中明显的基本途径和靶点。令人惊讶的是，这些分析揭示了 DHL具有独特的超级增强子(SE)景观，其中在DHL中出现的SE与以下基因相关 控制淋巴瘤细胞命运或致癌信号。此外，这些筛查显示DHL和Del细胞 LINE和原发患者样本对一般转录装置的抑制物高度敏感。在……里面 特别是，所有的DHL和Del细胞对THZ1都非常敏感，THZ1是一种新发现的细胞周期蛋白的共价抑制剂。 依赖激酶7(CDK7)，起转录辅助因子的作用，并使C末端磷酸化 RNA聚合酶-II的结构域。此外，我们对CDK9的选择性抑制剂NVP2的研究揭示了 DHL和Del细胞的生存也需要这种激酶的活性，它调节转录 伸长率。值得注意的是，我们的新发现证实了CDK7和CDK90的功能都是 维持DHL和DEL模型中MYC的表达。我们假设MYC-、CDK7-和CDK9- 依赖转录和bcl2的过度表达共同驱动肿瘤的侵袭性表型 DHL和Del，相应地，CDK7或CDK9和bcl2联合抑制触发合成 这些侵袭性淋巴瘤的致命性。使用我们基于细胞的平台，DHL和Del细胞系模型，DHL 我们实验室提供的患者来源的异种移植(PDX)和同基因小鼠DHL模型，我们的 各自的专业知识，以及我们获得大量原始DHL患者标本的独特途径，我们将解决 CDK7和CDK9在DHL维持中的作用，我们将确定CDK7/CDK9的机制 在这种致命的恶性肿瘤中维持致癌驱动因素的表达。最后，我们将战略性地瞄准 转录机制和临床前验证结合禁用药物的治疗策略 CDK7、CDK9和BCL2作为治疗DHL和DELL的综合治疗方法好了！

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. !