Ferguson L R, Whiteside G, Holdaway K M, Baguley B C
Cancer Research Laboratory, University of Auckland Medical School, New Zealand.
Environ Mol Mutagen. 1996;27(4):255-62. doi: 10.1002/(SICI)1098-2280(1996)27:4<255::AID-EM2>3.0.CO;2-C.
Amsacrine (4'-(9-acridinylamino)methanesulphon-m-anisidide) is an antileukemic drug which inhibits topoisomerase II (topo II) enzymes. We studied effects of two concentrations of amsacrine on the GM10115A cell line. This is a Chinese hamster line containing a single human chromosome 4, which can be readily visualised using fluorescence in situ hybridisation (FISH). The low amsacrine concentration slowed cell growth but did not cause significant arrest in the G2 phase of the cell cycle, while a higher concentration caused more long-term effects on the growth of the cells and caused G2 arrest. Either concentration led to chromosomal fragments which were lost with increasing time after treatment, and chromosomal translocations which appeared stable for at least 8 days after treatment. At the low concentration, the loss or gain of a single chromosome was a common event. The higher concentration led to polyploid cells, usually containing an uneven number of chromosome 4. We propose two mechanisms for aneuploidy by amsacrine (or related topo II poisons), either of which can be readily detected using FISH. At low drug concentrations, aneuploidy may occur directly through, for example, a failure to resolve catenated chromatids prior to anaphase. However, there has been considerable interest in the role of the cell division control (cdc) kinase and cyclins in regulating the mammalian cell cycle, and these may also be involved in the response of cells to high concentrations of topo II poisons. Cdc2 proteins and cyclins are involved in coordinating diverse activities during the M phase of the cell cycle, including catalysis of chromosome condensation and reorganisation of microtubules to allow chromosome separation during mitosis. Chromosome damage by topo II poisons will lead to G2 arrest, which allows the cells time to repair the damage. During this time, cyclin A and cdc2 levels will fall, preventing the cell from entering mitosis and effectively resetting the clock to G1 and the ploidy to tetraploid. Aneuploid cells will derive from polyploid cells through loss of extra chromosomes.
安吖啶（4'-（9-吖啶基氨基）甲磺酰基间甲氧基苯胺）是一种抑制拓扑异构酶II（topo II）的抗白血病药物。我们研究了两种浓度的安吖啶对GM10115A细胞系的影响。这是一种含有单条人类4号染色体的中国仓鼠细胞系，可通过荧光原位杂交（FISH）轻松观察到。低浓度的安吖啶减缓了细胞生长，但未导致细胞周期G2期的显著停滞，而较高浓度对细胞生长产生了更长期的影响并导致G2期停滞。两种浓度均导致染色体片段在处理后随时间增加而丢失，以及染色体易位在处理后至少8天保持稳定。在低浓度下，单个染色体的丢失或增加是常见事件。较高浓度导致多倍体细胞，通常含有数量不均一的4号染色体。我们提出了安吖啶（或相关的topo II毒药）导致非整倍体的两种机制，使用FISH均可轻松检测到。在低药物浓度下，非整倍体可能直接通过例如后期之前未能解开连环染色单体而发生。然而，细胞分裂控制（cdc）激酶和细胞周期蛋白在调节哺乳动物细胞周期中的作用一直备受关注，它们也可能参与细胞对高浓度topo II毒药的反应。Cdc2蛋白和细胞周期蛋白参与协调细胞周期M期的各种活动，包括催化染色体凝聚和微管重组以允许有丝分裂期间染色体分离。topo II毒药引起的染色体损伤将导致G2期停滞，这使细胞有时间修复损伤。在此期间，细胞周期蛋白A和cdc2水平将下降，阻止细胞进入有丝分裂并有效地将时钟重置为G1期，将倍性重置为四倍体。非整倍体细胞将通过额外染色体的丢失从多倍体细胞产生。
