The Mre11 nuclease is critical for the sensitivity of cells to Chk1 inhibition.
The Mre11 nuclease is critical for the sensitivity of cells to Chk1 inhibition.
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DOI：
10.1371/journal.pone.0044021
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Eastman A
中科院分区：
文献类型：
--
作者：
Thompson R;Montano R;Eastman A
Chk 1激酶是DNA受损时阻止细胞周期进程和稳定停滞的复制叉所必需的。因此，许多Chk 1抑制剂已被开发和测试其增强DNA损伤诱导的肿瘤细胞杀伤的潜力。然而，单独抑制Chk 1，而没有任何额外的外源性试剂，可以是细胞毒性的。了解这种敏感性的潜在机制对于确定哪些患者可能对Chk 1抑制剂治疗反应最好至关重要。我们研究了U2 OS骨肉瘤细胞的敏感性机制。与Chk 1抑制剂MK-8776孵育后，6 h内出现单链DNA区域（ssDNA）和双链断裂（DSB）开始。这些DSB已归因于结构特异性DNA内切酶Mus 81。已知Mre 11/Rad 50/Nbs 1复合物负责将DSB切除为ssDNA。然而，我们发现，Mre 11核酸酶活性的抑制不仅导致Chk 1抑制后ssDNA的量减少，而且还抑制DSB的形成，这表明DSB是ssDNA形成的结果。这些发现得到了以下发现的证实：Mre 11缺陷型ATLD 1细胞对MK-8776具有高度耐药性，处理后既不形成ssDNA也不形成DSB。然而，一旦与外源性Mre 11互补，当与MK-8776孵育时，细胞积聚ssDNA和DSB。我们的研究结果表明，Mre 11提供了异常激活Cdc 25 A/Cdk 2和Mus 81之间的联系。结果强调了Mre 11在DSB产生中的新作用，并可能有助于确定哪些肿瘤对MK-8776单独或与DNA损伤剂联合更敏感。
The Chk1 kinase is required for the arrest of cell cycle progression when DNA is damaged, and for stabilizing stalled replication forks. As a consequence, many Chk1 inhibitors have been developed and tested for their potential to enhance DNA damage-induced tumor cell killing. However, inhibition of Chk1 alone, without any additional exogenous agent, can be cytotoxic. Understanding the underlying mechanisms of this sensitivity is critical for defining which patients might respond best to therapy with Chk1 inhibitors. We have investigated the mechanism of sensitivity in U2OS osteosarcoma cells. Upon incubation with the Chk1 inhibitor MK-8776, single-stranded DNA regions (ssDNA) and double-strand breaks (DSB) begin to appear within 6 h. These DSB have been attributed to the structure-specific DNA endonuclease, Mus81. The Mre11/Rad50/Nbs1 complex is known to be responsible for the resection of DSB to ssDNA. However, we show that inhibition of the Mre11 nuclease activity leads, not only to a decrease in the amount of ssDNA following Chk1 inhibition, but also inhibits the formation of DSB, suggesting that DSB are a consequence of ssDNA formation. These findings were corroborated by the discovery that Mre11-deficient ATLD1 cells are highly resistant to MK-8776 and form neither ssDNA nor DSB following treatment. However, once complimented with exogenous Mre11, the cells accumulate both ssDNA and DSB when incubated with MK-8776. Our findings suggest that Mre11 provides the link between aberrant activation of Cdc25A/Cdk2 and Mus81. The results highlight a novel role for Mre11 in the production of DSB and may help define which tumors are more sensitive to MK-8776 alone or in combination with DNA damaging agents.
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DOI：
10.1083/jcb.200905059
发表时间：
2010-03-08
期刊：
The Journal of cell biology
影响因子：
--
作者：
Beck H;Nähse V;Larsen MS;Groth P;Clancy T;Lees M;Jørgensen M;Helleday T;Syljuåsen RG;Sørensen CS
通讯作者：
Sørensen CS
影响因子：
16.8
作者：
通讯作者：
--
影响因子：
21.3
作者：
Jazayeri, A;Falck, J;Jackson, SP
通讯作者：
Jackson, SP
影响因子：
8
作者：
Bahassi, E. M.;Ovesen, J. L.;Stambrook, P. J.
通讯作者：
Stambrook, P. J.
影响因子：
15.3
作者：
Cuadrado, M;Martinez-Pastor, B;Fernandez-Capetillo, O
通讯作者：
Fernandez-Capetillo, O