Peterson Yuri K, Kelly Patrick, Weinbaum Carolyn A, Casey Patrick J
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Biol Chem. 2006 May 5;281(18):12445-50. doi: 10.1074/jbc.M600168200. Epub 2006 Mar 3.
Inhibiting protein prenylation is an attractive means to modulate cellular processes controlled by a variety of signaling proteins, including oncogenic proteins such as Ras and Rho GTPases. The largest class of prenylated proteins contain a so-called CaaX motif at their carboxyl termini and are subject to a maturation process initiated by the attachment of an isoprenoid lipid by either protein farnesyltransferase (FTase) or protein geranylgeranyltransferase type I (GGTase-I). Inhibitors of FTase, termed FTIs, have been the subject of intensive development in the past decade and have shown efficacy in clinical trials. Although GGTase-I inhibitors (GGTIs) have received less attention, accumulating evidence suggests GGTIs may augment therapies using FTIs and could be useful to treat a myriad of additional disease states. Here we describe the characterization of a selective, highly potent, and cell-active GGTase-I inhibitor, GGTI-DU40. Kinetic analysis revealed that inhibition by GGTI-DU40 is competitive with the protein substrate and uncompetitive with the isoprenoid substrate; the Ki for the inhibition is 0.8 nM. GGTI-DU40 is highly selective for GGTase-I both in vitro and in living cells. Studies indicate GGTI-DU40 blocks prenylation of a number of geranylgeranylated CaaX proteins. Treatment of MDA-MB-231 breast cancer cells with GGTI-DU40 inhibited thrombin-induced cell rounding via a process that involves inhibition of Rho proteins without significantly effecting parallel mobilization of calcium via Gbetagamma. These studies establish GGTI-DU40 as a prime tool for interrogating biologies associated with protein geranylgeranylation and define a novel structure for this emerging class of experimental therapeutics.
抑制蛋白质异戊二烯化是调节由多种信号蛋白控制的细胞过程的一种有吸引力的手段，这些信号蛋白包括致癌蛋白，如Ras和Rho GTP酶。最大一类异戊二烯化蛋白在其羧基末端含有一个所谓的CaaX基序，并经历一个成熟过程，该过程由蛋白质法尼基转移酶（FTase）或I型蛋白质香叶基香叶基转移酶（GGTase-I）连接类异戊二烯脂质引发。FTase抑制剂，称为FTIs，在过去十年中一直是深入研究的对象，并在临床试验中显示出疗效。尽管GGTase-I抑制剂（GGTIs）受到的关注较少，但越来越多的证据表明，GGTIs可能增强使用FTIs的治疗效果，并可能有助于治疗大量其他疾病状态。在此，我们描述了一种选择性、高效且具有细胞活性的GGTase-I抑制剂GGTI-DU40的特性。动力学分析表明，GGTI-DU40的抑制作用与蛋白质底物具有竞争性，与类异戊二烯底物具有非竞争性；抑制作用的Ki为0.8 nM。GGTI-DU40在体外和活细胞中对GGTase-I具有高度选择性。研究表明，GGTI-DU40可阻断多种香叶基香叶基化CaaX蛋白的异戊二烯化。用GGTI-DU40处理MDA-MB-231乳腺癌细胞可通过抑制Rho蛋白的过程抑制凝血酶诱导的细胞变圆，而不会通过Gβγ显著影响钙的平行动员。这些研究将GGTI-DU40确立为研究与蛋白质香叶基香叶基化相关生物学的主要工具，并为这类新兴的实验性治疗药物定义了一种新结构。
