The novel Chk1 inhibitor MK-8776 sensitizes human leukemia cells to HDAC inhibitors by targeting the intra-S checkpoint and DNA replication and repair.
The novel Chk1 inhibitor MK-8776 sensitizes human leukemia cells to HDAC inhibitors by targeting the intra-S checkpoint and DNA replication and repair.
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DOI：
10.1158/1535-7163.mct-12-0902
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发表时间：
2013-06
影响因子：
5.7
通讯作者：
Grant S
中科院分区：
文献类型：
--
作者：
Dai Y;Chen S;Kmieciak M;Zhou L;Lin H;Pei XY;Grant S
在含有野生型(Wt)或缺失p53的人白血病细胞中，研究了新型Chk1抑制剂MK-8776和HDAC抑制剂(HDACi)涡旋器之间的相互作用。MK-8776协同增强P53野生型(Wt)或缺陷型白血病细胞系的细胞凋亡，而shRNA下调P53则使P53-wt细胞对该方案的致死性增敏。携带Flt3-ITD的白血病细胞株对MK-8776/Vor-inostat方案也敏感。协同作用与抑制Chk1活性，干扰S期检查点，干扰DNA复制，下调参与DNA复制和修复的蛋白质(如ctIP和BRCA1)，导致DNA损伤急剧增加，反映为γH2A.X的形成，以及细胞凋亡有关。此外，与野生型相比，表达激酶死亡的Chk1(D130A)或Chk1 shRNA的白血病细胞对HDACi明显更敏感，并且在HDACi暴露后表现出CtIP和BRCA1磷酸化的下调。最后，MK-8776/Vorinostat方案在原代AML原始细胞中是有效的，特别是对富含白血病启动细胞的CD34+/CD38-/CD123+群体。相比之下，相同的方案相对较少使用正常的脐带血CD34+细胞。综上所述，这些发现表明，新型Chk1抑制剂MK-8776通过破坏S内部检查点、DNA复制和DNA修复等机制，显著增强了具有不同遗传背景的白血病细胞的HDACI杀伤力。他们还认为，白血病细胞，包括那些带有与预后不良相关的癌基因突变的细胞，如p53缺失/突变或Flt3-ITD，也可能对这一策略敏感。
Interactions between the novel Chk1 inhibitor MK-8776 and the HDAC inhibitor (HDACI) vorinostat were examined in human leukemia cells harboring wild-type (wt) or deficient p53. MK-8776 synergistically potentiated vorinostat-mediated apoptosis in various p53-wild type (wt) or -deficient leukemia cell lines, while p53 knock-down by shRNA sensitized p53-wt cells to lethality of this regimen. Leukemia cell lines carrying FLT3-ITD were also sensitive to the MK-8776/vorinostat regimen. Synergistic interactions were associated with inhibition of Chk1 activity, interference with the intra-S phase checkpoint, disruption of DNA replication, and down-regulation of proteins involved in DNA replication (e.g.,CDT1) and repair (e.g., CtIP and BRCA1), resulting in sharp increases in DNA damage, reflected by enhanced γH2A.X formation, and apoptosis. Moreover, leukemia cells expressing kinase-dead Chk1 (D130A) or Chk1 shRNA were significantly more sensitive to HDACIs compared to their wild-type counterparts, and displayed down-regulation of CtIP and BRCA1 phosphorylation following HDACI exposure. Finally, the MK-8776/vorinostat regimen was active in primary AML blasts, particularly against the CD34+/CD38-/CD123+ population enriched for leukemia-initiating cells. In contrast, identical regimens were relatively sparing toward normal cord blood CD34+ cells. Together, these findings indicate that the novel Chk1 inhibitor MK-8776 markedly potentiates HDACI lethality in leukemia cells displaying various genetic backgrounds through mechanisms involving disruption of the intra-S checkpoint, DNA replication, and DNA repair. They also argue that leukemic cells, including those bearing oncogenic mutations associated with poor prognosis e.g., p53 deletion/mutation or FLT3-ITD, may also be susceptible to this strategy.