Deng Shiwei, Yan Tiandong, Nikolova Teodora, Fuhrmann Dominik, Nemecek Andrea, Gödtel-Armbrust Ute, Kaina Bernd, Wojnowski Leszek
Institute of Pharmacology, Medical Center of the University Mainz, Mainz, Germany.
Br J Pharmacol. 2015 May;172(9):2246-57. doi: 10.1111/bph.13046. Epub 2015 Feb 27.
The catalytic topoisomerase II inhibitor dexrazoxane has been associated not only with improved cancer patient survival but also with secondary malignancies and reduced tumour response.
We investigated the DNA damage response and the role of the activating transcription factor 3 (ATF3) accumulation in tumour cells exposed to dexrazoxane.
Dexrazoxane exposure induced topoisomerase IIα (TOP2A)-dependent cell death, γ-H2AX accumulation and increased tail moment in neutral comet assays. Dexrazoxane induced DNA damage responses, shown by enhanced levels of γ-H2AX/53BP1 foci, ATM (ataxia telangiectasia mutated), ATR (ATM and Rad3-related), Chk1 and Chk2 phosphorylation, and by p53 accumulation. Dexrazoxane-induced γ-H2AX accumulation was dependent on ATM. ATF3 protein was induced by dexrazoxane in a concentration- and time-dependent manner, which was abolished in TOP2A-depleted cells and in cells pre-incubated with ATM inhibitor. Knockdown of ATF3 gene expression by siRNA triggered apoptosis in control cells and diminished the p53 protein level in both control and dexrazoxane -treated cells. This was accompanied by increased γ-H2AX accumulation. ATF3 knockdown also delayed the repair of dexrazoxane -induced DNA double-strand breaks.
As with other TOP2A poisons, dexrazoxane induced DNA double-strand breaks followed by activation of the DNA damage response. The DNA damage-triggered ATF3 controlled p53 accumulation and generation of double-strand breaks and is proposed to serve as a switch between DNA damage and cell death following dexrazoxane treatment. These findings suggest a mechanistic explanation for the diverse clinical observations associated with dexrazoxane.
催化性拓扑异构酶II抑制剂右丙亚胺不仅与癌症患者生存率提高有关，还与继发性恶性肿瘤及肿瘤反应降低有关。
我们研究了暴露于右丙亚胺的肿瘤细胞中的DNA损伤反应以及激活转录因子3（ATF3）积累的作用。
右丙亚胺暴露诱导了拓扑异构酶IIα（TOP2A）依赖性细胞死亡、γ-H2AX积累，并在中性彗星试验中增加了尾部矩。右丙亚胺诱导了DNA损伤反应，表现为γ-H2AX/53BP1焦点、共济失调毛细血管扩张突变蛋白（ATM）、ATM和Rad3相关蛋白（ATR）、细胞周期蛋白依赖性激酶1（Chk1）和细胞周期蛋白依赖性激酶2（Chk2）磷酸化水平升高，以及p53积累。右丙亚胺诱导的γ-H2AX积累依赖于ATM。右丙亚胺以浓度和时间依赖性方式诱导ATF3蛋白，在TOP2A缺失的细胞和用ATM抑制剂预孵育的细胞中这种诱导作用消失。用小干扰RNA（siRNA）敲低ATF3基因表达在对照细胞中引发凋亡，并降低了对照细胞和右丙亚胺处理细胞中的p53蛋白水平。这伴随着γ-H2AX积累增加。ATF3敲低也延迟了右丙亚胺诱导的DNA双链断裂的修复。
与其他TOP2A毒物一样，右丙亚胺诱导DNA双链断裂，随后激活DNA损伤反应。DNA损伤引发的ATF3控制p53积累和双链断裂的产生，并被认为是右丙亚胺治疗后DNA损伤与细胞死亡之间的一个开关。这些发现为与右丙亚胺相关的各种临床观察结果提供了一个机制解释。
