SIRT1 inhibition impairs non-homologous end joining DNA damage repair by increasing Ku70 acetylation in chronic myeloid leukemia cells.
SIRT1 inhibition impairs non-homologous end joining DNA damage repair by increasing Ku70 acetylation in chronic myeloid leukemia cells.
复制标题
SIRT1 抑制通过增加慢性粒细胞白血病细胞中 Ku70 乙酰化来损害非同源末端连接 DNA 损伤修复
DOI：
10.18632/oncotarget.6455
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发表时间：
2016-03-22
期刊：
影响因子：
--
通讯作者：
Liang A
中科院分区：
文献类型：
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作者：
Zhang W;Wu H;Yang M;Ye S;Li L;Zhang H;Hu J;Wang X;Xu J;Liang A
大多数白血病化疗药物是DNA损伤剂。然而，DNA损伤可以通过DNA修复系统的活性来修复。越来越多的证据表明，增强的DNA损伤修复能力有助于白血病细胞的化疗耐药性。因此，靶向DNA修复机制是新的白血病治疗的有前途的策略。慢病毒介导的SIRT 1 shRNA下调髓系白血病细胞中SIRT 1的表达。分别采用实时荧光定量PCR和Western blot分析SIRT 1 mRNA和蛋白水平。流式细胞仪检测细胞周期进程、凋亡及DNA损伤修复效率。通过碱性彗星试验评估DNA损伤水平，并通过免疫印迹和免疫荧光分析H2 AX磷酸化。将携带SIRT 1 shRNA的慢病毒感染K562细胞移植到亚致死剂量照射的NOD/SCID小鼠体内，建立小鼠白血病模型，通过检测肿瘤重量和小鼠存活率来评价肿瘤发生。SIRT 1在髓系白血病患者中表达上调。通过RNAi下调SIRT 1可促进足叶乙甙诱导的髓性白血病细胞DNA损伤，并伴有NHEJ活性降低和Ku 70乙酰化增加。此外，SIRT 1敲低导致细胞周期阻滞，诱导凋亡和K562细胞增殖减少，并伴随着增强p53和FOXO 1乙酰化后，依托泊苷处理K562细胞。重要的是，SIRT 1下调降低了化疗治疗后小鼠异种移植物中K562细胞的肿瘤发生能力。这些结果表明，SIRT 1通过使K562细胞中的Ku 70脱乙酰化来促进NHEJ修复途径，表明SIRT 1是治疗髓性白血病的新的治疗靶点。
Most chemotherapeutic agents for leukemia are DNA damaging agents. However, DNA lesions can be repaired by activities of DNA repair systems. Increasing evidence have shown that enhanced DNA damage repair capacity contributes to chemotherapy resistance in leukemia cells. Thus, targeting DNA repair mechanisms is a promising strategy for novel leukemia treatment. SIRT1 expressions were downregulated by lentivirus-delivered SIRT1 shRNA in myeloid leukemia cells. SIRT1 mRNA and protein levels were analyzed by real-time PCR and Western blot, respectively. Flow cytometry was carried out to analyze cell cycle progression, apoptosis and DNA damage repair efficiency. DNA damage levels were assessed by alkaline comet assay, and H2AX phosphorylation was analyzed by immunoblotting and immunofluorescence. A mouse leukemia model was established by transplanting lentivirus-infected K562 cells containing SIRT1 shRNA into sublethally irradiated NOD/SCID mice, and tumorigenesis was evaluated by detecting tumor weights and mice survival. SIRT1 expressions were upregulated in myeloid leukemic patients. Downregulation of SIRT1 by RNAi promoted etoposide-induced DNA damage in myeloid leukemia cells accompanied by reduced NHEJ activity, and increased Ku70 acetylation. Furthermore, SIRT1 knockdown resulted in cell cycle arrest, induction of apoptosis and reduction of K562 cell proliferation accompanied by enhanced p53 and FOXO1 acetylation in K562 cells after etoposide treatment. Importantly, SIRT1 downregulation reduced the tumorigenesis ability of K562 cells in mouse xenografts following chemotherapy treatment. These results revealed that SIRT1 promotes the NHEJ repair pathway by deacetylating Ku70 in K562 cells, suggesting that SIRT1 is a novel therapeutic target for treating myeloid leukemia.