Svensson F, Mett H, Persson L
Department of Physiology and Neuroscience, University of Lund, Sweden.
Biochem J. 1997 Feb 15;322 ( Pt 1)(Pt 1):297-302. doi: 10.1042/bj3220297.
Mammalian S-adenosylmethionine decarboxylase (AdoMetDC) catalyses a regulatory important step in the biosynthesis of polyamines and is a potential target for therapeutic agents against various parasitic diseases and proliferative disorders. In the present study we examined the effects of a newly synthesized AdoMetDC inhibitor. 4-amidinoindan-1-one 2'-amidinohydrazone (CGP 48664), on polyamine metabolism in the mouse leukaemia cell line L1210. Treatment of the cells with 2 microM CGP 48664 led to a depletion of cellular spermidine and spermine. The putrescine content, in contrast, was markedly increased. Cells seeded in the presence of the inhibitor showed a significant decrease in growth rate, which was fully reversed by the addition of 2 microM spermidine or 1 microM spermine. The syntheses of ornithine decarboxylase and AdoMetDC were greatly increased in cells treated with CGP 48664. These increases were not correlated with similar changes in the mRNA levels, indicating the involvement of a translational mechanism. CGP 48664 was demonstrated to be a very poor competitor of spermidine uptake in the L1210 cells. L1210 cells deficient in polyamine transport were as sensitive to the antiproliferative effect of the inhibitor as were the parental cells, indicating that CGP 48664 did not enter the cells by the polyamine transport system. In addition to inhibiting AdoMetDC, CGP 48664 stabilized the enzyme against degradation. In the present study we also demonstrated that aminoguanidine (AMG), which is frequently used in cellular systems to inhibit any action of serum polyamine oxidase, apparently inhibits AdoMetDC by an irreversible mechanism that markedly stabilizes the enzyme against proteolytic degradation. CGP 48664 and the parental compound methylglyoxal bis(guanylhydrazone), which is also a potent inhibitor of AdoMetDC, contain one or two AMG-like moieties; the importance of these residues in the inhibition of AdoMetDC is discussed.
哺乳动物的S-腺苷甲硫氨酸脱羧酶（AdoMetDC）催化多胺生物合成中一个具有重要调节作用的步骤，并且是针对各种寄生虫病和增殖性疾病的治疗药物的潜在靶点。在本研究中，我们检测了一种新合成的AdoMetDC抑制剂4-脒基茚满-1-酮2'-脒基腙（CGP 48664）对小鼠白血病细胞系L1210中多胺代谢的影响。用2 μM CGP 48664处理细胞导致细胞内亚精胺和精胺耗竭。相比之下，腐胺含量显著增加。在抑制剂存在下接种的细胞生长速率显著降低，添加2 μM亚精胺或1 μM精胺可使其完全逆转。在用CGP 48664处理的细胞中，鸟氨酸脱羧酶和AdoMetDC的合成大幅增加。这些增加与mRNA水平的类似变化无关，表明涉及翻译机制。已证明CGP 48664在L1210细胞中是亚精胺摄取的非常弱的竞争者。缺乏多胺转运的L1210细胞与亲代细胞一样对抑制剂的抗增殖作用敏感，表明CGP 48664不是通过多胺转运系统进入细胞的。除了抑制AdoMetDC外，CGP 48664还使该酶稳定而不被降解。在本研究中我们还证明，在细胞系统中常用于抑制血清多胺氧化酶任何作用的氨基胍（AMG）显然通过一种不可逆机制抑制AdoMetDC，该机制显著使该酶稳定而不被蛋白水解降解。CGP 48664和亲代化合物甲基乙二醛双（胍基腙）（它也是AdoMetDC的有效抑制剂）含有一个或两个类似AMG的基团；讨论了这些残基在抑制AdoMetDC中的重要性。
