Byers T L, Ganem B, Pegg A E
Department of Cellular and Molecular Physiology, M.S. Hershey Medical Center, Hershey, PA 17033.
Biochem J. 1992 Nov 1;287 ( Pt 3)(Pt 3):717-24. doi: 10.1042/bj2870717.
The effects of inhibition of the capacity to form spermidine and spermine on cell growth were investigated using murine leukaemia L1210 cells and 5'-([(Z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine (MDL 73811, AbeAdo), an enzyme-activated irreversible inhibitor of S-adenosyl-L-methionine decarboxylase. Putrescine levels were increased 80-fold, and spermidine and spermine levels were greatly reduced after a 3-day exposure to a maximally inhibitory dose of 10 microM-AbeAdo. Addition of AbeAdo to the culture medium inhibited the growth of L1210 cells measured 3 days later in a dose-dependent manner, but, even at a dose of 10 microM, which was maximally effective, exposure to AbeAdo was not immediately cytostatic. However, the growth rate of L1210 cells chronically exposed to 10 microM-AbeAdo declined steadily until day 12, when the cells stopped growing. L1210 cells exposed to AbeAdo for 12 days could not be rescued from cytostasis by removal of the drug from the culture, but could be rescued by exposure to exogenous spermidine or spermine, indicating that the growth-inhibitory effects of AbeAdo were a result of spermidine and/or spermine depletion. It is suggested that elevated intracellular putrescine in AbeAdo-treated cells sustained limited growth in the absence of physiological levels of spermidine and spermine until certain critical and specific physiological role(s) fulfilled by spermidine (and/or spermine) became deficient resulting in cytostasis. N-(3-Aminopropyl)-1,4-diamino-cis-but-2-ene, a spermidine analogue that is a substrate for deoxyhypusine synthase, was able to mimic the effects of spermidine in reversing AbeAdo-induced cytostasis. Spermidine analogues such as 5,5-dimethylspermidine, which are not substrates for deoxyhypusine synthase, were not active in this way. These results provide evidence that the formation of hypusine in the protein-synthesis initiation factor eIF-5A may be a critical role of spermidine essential for cell growth.
使用小鼠白血病L1210细胞和5'-([(Z)-4-氨基-2-丁烯基]甲基氨基)-5'-脱氧腺苷（MDL 73811，AbeAdo，一种S-腺苷-L-甲硫氨酸脱羧酶的酶激活不可逆抑制剂），研究了抑制亚精胺和精胺形成能力对细胞生长的影响。在最大抑制剂量10μM - AbeAdo下暴露3天后，腐胺水平增加了80倍，亚精胺和精胺水平大幅降低。向培养基中添加AbeAdo以剂量依赖性方式抑制3天后测定的L1210细胞生长，但即使在最大有效剂量10μM下，暴露于AbeAdo也不会立即产生细胞生长抑制作用。然而，长期暴露于10μM - AbeAdo的L1210细胞的生长速率持续稳定下降，直到第12天细胞停止生长。暴露于AbeAdo 12天的L1210细胞不能通过从培养基中去除药物而从细胞生长抑制状态中恢复，但可以通过暴露于外源性亚精胺或精胺而恢复，这表明AbeAdo的生长抑制作用是亚精胺和/或精胺耗竭的结果。有人提出，在缺乏亚精胺和精胺的生理水平的情况下，AbeAdo处理的细胞中细胞内腐胺升高维持有限的生长，直到亚精胺（和/或精胺）所发挥的某些关键和特定生理作用变得不足，从而导致细胞生长抑制。N-(3-氨丙基)-1,4-二氨基-顺-2-丁烯，一种作为脱氧hypusine合酶底物的亚精胺类似物，能够模拟亚精胺在逆转AbeAdo诱导的细胞生长抑制方面的作用。而诸如5,5-二甲基亚精胺等不是脱氧hypusine合酶底物的亚精胺类似物，在这方面没有活性。这些结果提供了证据，表明蛋白质合成起始因子eIF-5A中hypusine的形成可能是细胞生长所必需的亚精胺的关键作用。
