A novel mechanism of cell killing by anti-topoisomerase II bisdioxopiperazines
A novel mechanism of cell killing by anti-topoisomerase II bisdioxopiperazines
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DOI：
10.1074/jbc.275.3.2137
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发表时间：
2000-01-21
影响因子：
4.8
通讯作者：
Nitiss, JL
中科院分区：
文献类型：
--
作者：
Jensen, LH;Nitiss, KC;Nitiss, JL
双氧哌嗪是一类独特的拓扑异构酶II抑制剂，它在酶反应周期的某个点锁定拓扑异构酶II，在DNA周围形成一个闭合的夹子。我们检测了ICRF-187和ICRF-193对表达人拓扑异构酶IIα(HTOP-IIα)的酵母细胞的杀伤作用。在酵母细胞中表达HTOP-IIα使其对ICRF-187和ICRF-193都敏感，与表达酵母拓扑异构酶II的细胞相比，ICRF 193仍然能够在编码ICRF-193抗性和ICRF-193敏感的HTOP-IIα酶的基因存在下发挥生长抑制作用，这表明对双二氧哌嗪的敏感性占主导地位。由于温度敏感的酵母拓扑异构酶II在不允许的温度下孵育，ICRF-193的杀灭作用比在酵母细胞中的杀灭作用发生得更快。这些结果使人想起TOP-II毒物，如依托泊苷，然而，ICRF-193和ICRF-187引起的杀伤并不因RAD52途径的突变而增强。用HTOP-IIα在体外观察到的药物诱导的DNA裂解水平不足以解释这种酶在酵母细胞中诱导的敏感性。最后，G(1)中细胞的停滞并不能保护细胞免受ICRF-193的致死，这一结果与杀伤机制不一致，这是由于催化抑制TOP-II或稳定可切割的复合体。我们认为，观察到的细胞杀伤模式与ICRF-193通过一种新的机制中毒HTOP-II最为一致。ICRF-193诱导的HTOP-II闭合钳构象在DNA上的聚集可能干扰转录或其他DNA代谢过程，导致细胞死亡。
Bisdioxopiperazines are a unique class of topoisomerase II inhibitors that lock topoisomerase II at a point in the enzyme reaction cycle where the enzyme forms a closed clamp around DNA, We examined cell killing by ICRF-187 and ICRF-193 in yeast cells expressing human topoisomerase II alpha (htop-II alpha). Expression of htop-II alpha in yeast cells sensitizes them to both ICRF-187 and ICRF-193, compared with cells expressing yeast topoisomerase II. ICRF 193 is still able to exert growth inhibition in the presence of genes encoding both ICRF-193-resistant and ICRF-193-sensitive htop-II alpha enzymes, indicating that sensitivity to bisdioxopiperazines is dominant. Killing by ICRF-193 occurs more rapidly, than the killing in yeast cells due to a temperature-sensitive yeast topoisomerase II incubated at the non-permissive temperature. These results are reminiscent of a top-II poison such as etoposide, However, the killing caused by ICRF-193 and ICRF-187 is not enhanced by mutations in the RAD52 pathway. The levels of drug-induced DNA cleavage observed with htop-II alpha in vitro is insufficient to explain the sensitivity induced by this enzyme in yeast cells. Finally, arrest of cells in G(1) does not protect cells from ICRF-193 lethality, a result inconsistent with killing mechanisms due to catalytic inhibition of top-II or stabilization of a cleavable complex. We suggest that the observed pattern of cell killing is most consistent with a poisoning of htop-II by ICRF-193 by a novel mechanism. The accumulation of closed clamp conformations of htop-II induced by ICRF-193 that are trapped on DNA might interfere with transcription, or other DNA metabolic processes, resulting in cell death.