Ishida R, Hamatake M, Wasserman R A, Nitiss J L, Wang J C, Andoh T
Laboratory of Biochemistry, Aichi Cancer Center Research Institute, Nagoya, Japan.
Cancer Res. 1995 Jun 1;55(11):2299-303.
Bisdioxopiperazines such as ICRF-159 and ICRF-193 have been shown to inhibit DNA topoisomerase II. To determine the molecular target of these compounds in vivo, we utilized a yeast genetic system in which the topoisomerase II activity can be modulated. To reduce topoisomerase II activity, we used top2-1 mutant yeast cells that have normal DNA topoisomerase II activity at 25 degrees C but greatly reduced enzyme activity at 30 degrees C, a temperature that is semipermissive for growth. At 25 degrees C top2-1 cells are as sensitive to the ICRF compounds as the wild-type strain; at 30 degrees C the cells became hypersensitive to these agents. In contrast, top2-1 strains become very resistant to the class of topoisomerase II inhibitors such as amsacrine and etoposide, which stabilize the covalent enzyme-DNA intermediate of the enzyme reaction. Overexpression of topoisomerase II from a plasmid-born TOP2 gene results in lower susceptibility to ICRF compounds and higher susceptibility to amsacrine than the parental strain exhibits. These results support the hypothesis that the main cellular target of ICRF compounds is DNA topoisomerase II, and that these compounds, unlike amsacrine and etoposide, inhibit topoisomerase II activity without stabilizing an enzyme-DNA covalent complex.
双二氧哌嗪类化合物，如ICRF - 159和ICRF - 193，已被证明可抑制DNA拓扑异构酶II。为了确定这些化合物在体内的分子靶点，我们利用了一种酵母遗传系统，其中拓扑异构酶II的活性可以被调节。为了降低拓扑异构酶II的活性，我们使用了top2 - 1突变酵母细胞，这些细胞在25摄氏度时具有正常的DNA拓扑异构酶II活性，但在30摄氏度时酶活性大大降低，30摄氏度是一个对生长半允许的温度。在25摄氏度时，top2 - 1细胞对ICRF化合物的敏感性与野生型菌株相同；在30摄氏度时，细胞对这些药物变得高度敏感。相比之下，top2 - 1菌株对拓扑异构酶II抑制剂类药物，如安吖啶和依托泊苷，变得非常耐药，这些抑制剂会稳定酶反应中的共价酶 - DNA中间体。从质粒携带的TOP2基因过表达拓扑异构酶II，与亲本菌株相比，对ICRF化合物的敏感性降低，对安吖啶的敏感性增加。这些结果支持了以下假设：ICRF化合物的主要细胞靶点是DNA拓扑异构酶II，并且这些化合物与安吖啶和依托泊苷不同，它们抑制拓扑异构酶II活性而不使酶 - DNA共价复合物稳定。
