Albertini S, Friederich U, Würgler F E
Pharmaceutical Research/Preclinical Development, F. Hoffmann-La Roche & Co. Ltd., Basel, Switzerland.
Mutagenesis. 1989 Jan;4(1):39-44. doi: 10.1093/mutage/4.1.39.
Gaulden reported a novel and unexpected mitomycin C (MMC) effect, namely a pronounced retardation of very late prophase and loss of chromosome orientation in neuroblasts of the grasshopper Chortophaga viridifasciate. Because this effect may be due to interactions of MMC with non-DNA targets, MMC was tested for its interaction with porcine brain tubulin assembly in vitro and for the induction of chromosomal malsegregation in the diploid yeast Saccharomyces cerevisiae strain D61.M. A reversible dose-dependent inhibition of tubulin assembly was observed. Since no biological activation system was present in the incubation mixture this inhibition seems to result from an interaction of unactivated MMC with the assembly process. The possible chemical activation of MMC by reduction with 1,4-dithioerythritol (DTE) was investigated by omission of this compound during isolation and polymerization of tubulin. The absence of DTE resulted in a strong reduction of the net tubulin assembly. Also under these conditions MMC led to a dose-dependent inhibition of the assembly, indicating that the effect of MMC on tubulin assembly is independent of a reductive chemical modification. In S. cerevisiae D61.M, MMC did not induce chromosome loss, but induced other genetic events (possibly mutations, deletions or mitotic recombination) as was detected by an increase of the total number and of the frequency of cycloheximide-resistant colonies. This effect could be observed with and without the addition of rat liver S9 as an exogenous activation system.
高尔登报道了一种新颖且意想不到的丝裂霉素C（MMC）效应，即在绿翅草螽神经母细胞中，有丝分裂前期极晚期显著延迟以及染色体取向丧失。由于这种效应可能是MMC与非DNA靶点相互作用所致，因此对MMC进行了体外与猪脑微管蛋白组装相互作用的测试，以及在二倍体酿酒酵母菌株D61.M中诱导染色体错分的测试。观察到微管蛋白组装受到可逆的剂量依赖性抑制。由于孵育混合物中不存在生物激活系统，这种抑制似乎是未激活的MMC与组装过程相互作用的结果。在微管蛋白的分离和聚合过程中，通过省略1,4 - 二硫代赤藓糖醇（DTE）来研究MMC是否可能被其还原而化学激活。缺少DTE导致微管蛋白净组装量大幅减少。在这些条件下，MMC也导致剂量依赖性的组装抑制，表明MMC对微管蛋白组装的影响与还原化学修饰无关。在酿酒酵母D61.M中，MMC未诱导染色体丢失，但诱导了其他遗传事件（可能是突变、缺失或有丝分裂重组），这通过环己酰亚胺抗性菌落总数和频率的增加得以检测。无论是否添加大鼠肝脏S9作为外源性激活系统，均可观察到这种效应。
