Targeting transcription-coupled DNA damage responses in CLL

靶向 CLL 中的转录偶联 DNA 损伤反应

• 批准号: 234150729
• 负责人: Dr. Marco Herling
• 金额: --
• 依托单位: Klinik für Innere Medizin I
• 依托单位国家: 德国
• 项目类别: Clinical Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/234150729?language=en
• 关键词: Targeting; transcription; coupled; DNA; damage

We evaluate the hypothesis that transcription-blocking DNA lesions are highly effective in the therapeutic targeting of CLL cells. The DNA repair group of Björn Schumacher teamed up with the translational group of Marco Herling to exploit transcription-coupled nucleotide excision repair (TC-NER) mechanisms to improve the therapeutic options for CLL. The hypothesis was derived from three specific characteristics. (1) CLL cells are typically residing in the G0/G1 phase and might therefore be less susceptible to conventional chemotherapy that often relies on inflicting DNA lesions that impair DNA replication. In contrast, TC-NER functions independently of the cell cycle to maintain integrity of actively transcribed genes. (2) In the current front-line CLL therapy the nucleoside analogue fludarabine exerts cytotoxic effects by poisoning the gap-filling step that completes the NER reaction. (3) Cellular responses to transcription-blocking lesions are independent of p53 or ATM and might therefore offer opportunities to effectively target clinically problematic chemo-resistant CLL cases. During the first funding period, we systematically conducted proof-of-concept studies. IlludinM, its derivative ferrocen-IM, and trabectedin were tested as 'TC-NER active' substances. IlludinM and ferrocen-IM inflict DNA lesions that are recognized by TC-NER. Trabectedin has been demonstrated to lead to highly cytotoxic lesions once its adducts are acted upon by TC-NER resulting in irreparable strand breaks. Confirming our hypothesis, those TC-NER active substances induced cell death in CLL cells that was independent of p53 or ATM and also effectively evoked in therapy-resistant CLL cells. Moreover, we determined synergies between fludarabine and TC-NER active substances. As an already clinically approved substance, we validated trabectedin in TCL1-driven murine models of CLL and determined its superior efficacy. We further performed small-molecule compound screens in TC-NER-deficient C. elegans that allows for the efficient selection of substances that trigger replication- and cell cycle-independent DNA damage responses, in vivo. We isolated inhibitors of Topoisomerase II (Topo II) and DNA polymerase alpha-primase (DNA pola). Genetic data from the nematode support the role of such types of thus far replication-associated factors in DNA repair in postmitotic cell types. We propose in phase-II of the project to (1) investigate the mechanisms of the p53/ATM-independent apoptosis in CLL cells induced by the TC-NER active compounds, (2) establish the mechanisms of Topo II and DNA pola inhibition-mediated replication-independent DNA damage response, and to (3) assess the potential clinical relevance of Topo II and DNA pola inhibition in CLL cells and mouse models in combination with TC-NER active substances. We expect to reveal new insights that will improve CLL therapy particularly of those CLL cases that are resistant to currently available treatment options.

我们评估了转录阻断DNA损伤在CLL细胞的治疗靶向中非常有效的假设。Björn Schumacher的DNA修复小组与Marco Herling的翻译小组合作，利用转录偶联核苷酸切除修复（TC-NER）机制来改善CLL的治疗选择。这一假设源于三个具体特征。(1)CLL细胞通常处于G 0/G1期，因此可能对常规化疗不太敏感，常规化疗通常依赖于造成损害DNA复制的DNA损伤。相反，TC-NER的功能独立于细胞周期，以保持活跃转录基因的完整性。(2)在目前的一线CLL治疗中，核苷类似物氟达拉滨通过毒化完成NER反应的间隙填充步骤来发挥细胞毒性作用。(3)对转录阻断病变的细胞反应独立于p53或ATM，因此可能提供有效靶向临床上有问题的化疗耐药CLL病例的机会。在第一个资助期内，我们系统地进行了概念验证研究。IlludinM、其衍生物二茂铁-IM和trabectedin被测试为“TC-NER活性”物质。IlludinM和二茂铁-IM造成的DNA损伤被TC-NER识别。已经证明，一旦其加合物被TC-NER作用，导致不可修复的链断裂，则曲贝替丁会导致高度细胞毒性病变。证实了我们的假设，这些TC-NER活性物质诱导CLL细胞的细胞死亡，这是独立于p53或ATM的，也有效地诱发了治疗抗性CLL细胞。此外，我们确定了氟达拉滨和TC-NER活性物质之间的协同作用。作为一种已经临床批准的物质，我们在TCL 1驱动的CLL小鼠模型中验证了trabectedin，并确定了其上级疗效。我们进一步在TC-NER缺陷的C中进行小分子化合物筛选。elegans，允许在体内有效选择触发复制和细胞周期独立的DNA损伤反应的物质。我们分离了拓扑异构酶II（Topo II）和DNA聚合酶α-引发酶（DNA pola）的抑制剂。从线虫的遗传数据支持的作用，这种类型的复制相关因子，迄今在有丝分裂后的细胞类型的DNA修复。我们计划在项目的第二阶段（1）研究TC-NER活性化合物诱导CLL细胞中p53/ATM非依赖性凋亡的机制，（2）建立Topo II和DNA pola抑制介导的复制非依赖性DNA损伤反应的机制，和（3）评估与TC-NER活性物质组合的CLL细胞和小鼠模型中Topo II和DNA pola抑制的潜在临床相关性。我们希望揭示新的见解，这将改善CLL治疗，特别是那些对目前可用的治疗方案有抵抗力的CLL病例。