Temozolomide-mediated DNA methylation in human myeloid precursor cells: differential involvement of intrinsic and extrinsic apoptotic pathways.
Temozolomide-mediated DNA methylation in human myeloid precursor cells: differential involvement of intrinsic and extrinsic apoptotic pathways.
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DOI：
10.1158/1078-0432.ccr-12-2671
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发表时间：
2013-05-15
期刊：
影响因子：
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通讯作者：
Pollok KE
中科院分区：
文献类型：
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作者：
Wang H;Cai S;Ernstberger A;Bailey BJ;Wang MZ;Cai W;Goebel WS;Czader MB;Crean C;Suvannasankha A;Shokolenkoc I;Wilson GL;Baluyut AR;Mayo LD;Pollok KE
了解造血细胞对导致骨髓抑制的治疗的反应将有助于开发预防这种潜在危及生命的毒性的方法。本研究的目的是确定人类髓样前体细胞（MP）如何对替莫唑胺（TMZ）诱导的DNA损伤作出反应。我们开发了一种离体原代人MP细胞模型系统，使用已知的O 6-苄基鸟嘌呤（6 BG）和TMZ的骨髓抑制方案来研究细胞死亡途径的参与。暴露于6 BG/TMZ导致p53、p21、γ-H2 AX和线粒体DNA损伤增加。6 BG/TMZ处理后，线粒体膜去极化的增加与caspase-9和caspase-3活性的增加相关。这些事件与活化AKT减少、DNA修复蛋白O 6甲基鸟嘌呤-DNA甲基转移酶（MGMT）下调和细胞死亡增加相关。在MP细胞扩增期间，FAS/CD 95/APO 1（FAS）表达随时间推移而增加，并且在暴露于6 BG/TMZ后存在于约100%的细胞上。虽然c-flipshort，一种FAS介导的信号传导的内源性抑制剂，在6 BG/TMZ处理的细胞中与对照、6 BG或TMZ单独处理的细胞相比减少，但胱天蛋白酶-8活性没有变化。此外，在存在中和或激动性抗FAS抗体的情况下，暴露于6 BG/TMZ的MP细胞的细胞死亡程度没有变化，表明FAS介导的信号传导不起作用。在人MP细胞中，6 BG/TMZ引发的凋亡通过内源性的、细胞介导的而非外源性的、FAS介导的凋亡发生。人MP细胞代表了一种临床相关的模型系统，用于深入了解造血细胞如何对化疗药物作出反应，并提供了一种选择具有有限造血毒性的有效化疗方案的方法。
An understanding of how hematopoietic cells respond to therapy that causes myelosuppression will help develop approaches to prevent this potentially life-threatening toxicity. The goal of this study was to determine how human myeloid precursor cells (MP) respond to temozolomide (TMZ)-induced DNA damage. We developed an ex vivo primary human MP cells model system to investigate the involvement of cell-death pathways using a known myelosuppressive regimen of O6-benzylguanine (6BG) and TMZ. Exposure to 6BG/TMZ led to increases in p53, p21, γ-H2AX, and mitochondrial DNA damage. Increases in mitochondrial membrane depolarization correlated with increased caspase-9 and caspase-3 activities following 6BG/TMZ treatment. These events correlated with decreases in activated AKT, downregulation of the DNA repair protein O6methylguanine-DNA methyltransferase (MGMT), and increased cell death. During MP cell expansion, FAS/CD95/APO1(FAS) expression increased over time and was present on ~100% of the cells following exposure to 6BG/TMZ. While c-flipshort, an endogenous inhibitor of FAS-mediated signaling, was decreased in 6BG/TMZ-treated versus control, 6BG-, or TMZ alone-treated cells, there were no changes in caspase-8 activity. Additionally, there were no changes in the extent of cell death in MP cells exposed to 6BG/TMZ in the presence of neutralizing or agonistic anti-FAS antibodies, indicating that FAS-mediated signaling was not operative. In human MP cells, 6BG/TMZ-initiated apoptosis occurred by intrinsic, mitochondrial-mediated and not extrinsic, FAS-mediated apoptosis. Human MP cells represent a clinically relevant model system for gaining insight into how hematopoietic cells respond to chemotherapeutics and offer an approach for selecting effective chemotherapeutic regimens with limited hematopoietic toxicity.