TDP2-dependent non-homologous end-joining protects against topoisomerase II-induced DNA breaks and genome instability in cells and in vivo.
TDP2-dependent non-homologous end-joining protects against topoisomerase II-induced DNA breaks and genome instability in cells and in vivo.
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DOI：
10.1371/journal.pgen.1003226
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发表时间：
2013
期刊：
影响因子：
4.5
通讯作者：
Cortés-Ledesma F
中科院分区：
文献类型：
--
作者：
Gómez-Herreros F;Romero-Granados R;Zeng Z;Alvarez-Quilón A;Quintero C;Ju L;Umans L;Vermeire L;Huylebroeck D;Caldecott KW;Cortés-Ledesma F
抗癌拓扑异构酶“毒药”利用拓扑异构酶II （TOP2）的断裂和重新连接机制产生TOP2连接的DNA双链断裂（DSBs）。这一特点奠定了TOP2毒物临床疗效的基础，但也涉及与继发性治疗相关的血液系统恶性肿瘤相关的染色体易位和基因组不稳定。尽管这与癌症治疗相关，但控制top2诱导的dsb修复的机制方面以及缺失或异常修复可能产生的生理后果仍然知之甚少。为了解决这些缺陷，我们使用缺乏酪氨酸DNA磷酸二酯酶2 （TDP2）的细胞和小鼠，研究它们对TOP2毒素的反应。TDP2是一种酶，可水解TOP2相关dsb上的5 ' -磷酸酪氨酸键。我们的研究结果表明，TDP2在非同源末端连接（NHEJ）中起作用，并释放具有连接能力的DSB末端。此外，我们发现细胞中缺乏TDP2不仅会损害修复top2诱导的dsb的能力，还会损害修复过程的准确性，从而损害基因组的完整性。最重要的是，我们发现这种依赖tdp2的NHEJ机制具有生理相关性，因为tdp2缺失的小鼠对top2诱导的损伤敏感，表现出明显的淋巴毒性、严重的肠道损伤和骨髓基因组不稳定性增加。总的来说，我们的数据揭示了tdp2介导的无错误NHEJ是修复top2诱导的dsb的有效和准确的机制。鉴于TOP2毒物在癌症化疗中的广泛使用，这提出了TDP2可能是肿瘤对这类药物反应和治疗相关恶性肿瘤发展的重要病因因素。DNA双链断裂（DSBs）是危险的，因为如果不进行修复，它们会导致细胞死亡和组织退化，或者如果修复不当，会导致基因组重排（这是癌症的常见标志）。虽然细胞中所有的染色体转变都需要拓扑异构酶II （TOP2）的瞬时DNA切割，但它是dsb的潜在内源，其特点是TOP2仍然与DNA末端共价结合。此外，许多化疗方案依赖于“毒害”TOP2活性的化合物，刺激靶向肿瘤细胞的dsb的形成。然而，这些化合物也会影响健康组织并产生不良副作用，包括刺激可引发继发性恶性肿瘤（主要是急性白血病）的基因组重排。因此，确定参与top2诱导的dsb修复的因子并充分了解其作用机制对于设计更有效、更安全的化疗方案至关重要。在这里，我们证明了TDP2是一种最近发现的蛋白，可以从被阻断的TOP2中释放DSB末端，作为已建立的细胞DSB修复过程的一部分，并且在细胞和小鼠中都需要在TOP2毒物治疗时保护基因组完整性。因此，这些结果可能对癌症治疗具有重要意义。
Anticancer topoisomerase “poisons” exploit the break-and-rejoining mechanism of topoisomerase II (TOP2) to generate TOP2-linked DNA double-strand breaks (DSBs). This characteristic underlies the clinical efficacy of TOP2 poisons, but is also implicated in chromosomal translocations and genome instability associated with secondary, treatment-related, haematological malignancy. Despite this relevance for cancer therapy, the mechanistic aspects governing repair of TOP2-induced DSBs and the physiological consequences that absent or aberrant repair can have are still poorly understood. To address these deficits, we employed cells and mice lacking tyrosyl DNA phosphodiesterase 2 (TDP2), an enzyme that hydrolyses 5′-phosphotyrosyl bonds at TOP2-associated DSBs, and studied their response to TOP2 poisons. Our results demonstrate that TDP2 functions in non-homologous end-joining (NHEJ) and liberates DSB termini that are competent for ligation. Moreover, we show that the absence of TDP2 in cells impairs not only the capacity to repair TOP2-induced DSBs but also the accuracy of the process, thus compromising genome integrity. Most importantly, we find this TDP2-dependent NHEJ mechanism to be physiologically relevant, as Tdp2-deleted mice are sensitive to TOP2-induced damage, displaying marked lymphoid toxicity, severe intestinal damage, and increased genome instability in the bone marrow. Collectively, our data reveal TDP2-mediated error-free NHEJ as an efficient and accurate mechanism to repair TOP2-induced DSBs. Given the widespread use of TOP2 poisons in cancer chemotherapy, this raises the possibility of TDP2 being an important etiological factor in the response of tumours to this type of agent and in the development of treatment-related malignancy. DNA double-strand breaks (DSBs) are dangerous because they can lead to cellular death and tissue degeneration if not repaired, or to genome rearrangements, which are a common hallmark of cancer, if repaired incorrectly. Although required for all chromosomal transitions in cells, transient DNA cleavage by topoisomerase II (TOP2) is a potential endogenous source of DSBs, which are characteristic in that TOP2 remains covalently bound to the DNA termini. In addition, numerous chemotherapeutic regimes rely on compounds that “poison” TOP2 activity, stimulating the formation of DSBs that target tumour cells. However, these compounds also affect healthy tissue and confer undesirable side effects, including the stimulation of genome rearrangements that can trigger secondary malignancies (mainly acute leukemia). Identifying the factors that participate in the repair of TOP2-induced DSBs and fully understanding their mechanism of action are therefore important for the design of chemotherapeutic regimes that are more effective and safer. Here we demonstrate that TDP2, a recently identified protein that can liberate DSB termini from blocked TOP2, functions as part of established cellular DSB repair processes and is required to safeguard genome integrity upon treatment with TOP2 poisons, both in cells and in mice. These results can therefore have important implications in cancer treatment.
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影响因子：
30.8
作者：
通讯作者：
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影响因子：
3.7
作者：
ALBAIN, KS;LEBEAU, MM;SCHUMACHER, H
通讯作者：
SCHUMACHER, H
影响因子：
9.8
作者：
Mirault, Marc-Edouard;Boucher, Patrick;Tremblay, Alain
通讯作者：
Tremblay, Alain
影响因子：
16.8
作者：
通讯作者：
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DOI：
10.1038/nrc2608
发表时间：
2009-05
期刊：
Nature reviews. Cancer
影响因子：
--
作者：
通讯作者：
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