Bishop W R, Bond R, Petrin J, Wang L, Patton R, Doll R, Njoroge G, Catino J, Schwartz J, Windsor W
Department of Molecular Pharmacology, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA.
J Biol Chem. 1995 Dec 22;270(51):30611-8. doi: 10.1074/jbc.270.51.30611.
Ras protooncogenes encode 21-kDa membrane-associated guanine nucleotide-binding proteins, which play a critical role in control of cellular proliferation and differentiation. Oncogenic, activated forms of Ras proteins are associated with a broad range of human cancers. The elucidation of the post-translational modifications that occur at the carboxyl terminus of Ras and the demonstration that farnesylation of Ras by farnesyl protein transferase is essential for Ras-induced cellular transformation has opened up a new and promising approach to the development of anti-Ras therapeutics. We report here a novel series of potent farnesyl protein transferase (FPT) inhibitors, represented by SCH 44342. This compound inhibits both rat brain and recombinant human FPT with an IC50 of approximately 250 nM, while it is only weakly active against rat brain geranylgeranyl protein transferase-1 (IC50 > 114 microM). FPT inhibition has been observed using both Ha-Ras protein and Ki-Ras-derived peptide substrates in two different assay formats. SCH 44342 and its analogs also inhibit farnesylation of Ras in Cos cells transiently expressing [Val12]Ha-Ras with IC50 values in the low micromolar range. At these concentrations they do not inhibit sterol biosynthesis or geranylgeranylation of protein. In addition, we observed that Cos cells undergo pronounced morphological changes upon overexpression of [Val12]activated forms of Ha-Ras containing COOH-terminal sequences allowing farnesylation (CVLS) or geranylgeranylation (CVLL) but not upon overexpression of activated Ras lacking the isoprenylated Cys (SVLS). Ras-induced morphological changes can be partially reverted with lovastatin. Importantly, SCH 44342 can block morphological changes induced by [Val12]Ha-Ras-CVLS but not [Val12]Ha-Ras-CVLL. Recently, a number of other FPT inhibitors have been reported. Most of the compounds reported to have cell-based activity are peptidomimetic analogs of the CAAX substrate. Our FPT inhibitors are novel in that although they compete with Ras protein in kinetic experiments they are entirely nonpeptidic in nature, they do not have oxidizable sulfhydryl functions, and they are active in cells at low micromolar concentrations.
Ras原癌基因编码21 kDa的膜相关鸟嘌呤核苷酸结合蛋白，其在细胞增殖和分化的控制中起关键作用。致癌的、活化形式的Ras蛋白与多种人类癌症相关。对Ras羧基末端发生的翻译后修饰的阐明以及法尼基蛋白转移酶对Ras的法尼基化是Ras诱导细胞转化所必需的这一证明，为抗Ras治疗药物的开发开辟了一条新的、有前景的途径。我们在此报告了一系列以SCH 44342为代表的新型强效法尼基蛋白转移酶（FPT）抑制剂。该化合物抑制大鼠脑和重组人FPT，IC50约为250 nM，而对大鼠脑香叶基香叶基蛋白转移酶-1活性较弱（IC50 > 114 μM）。在两种不同的测定形式中，使用Ha-Ras蛋白和Ki-Ras衍生的肽底物均观察到了FPT抑制作用。SCH 44342及其类似物还抑制瞬时表达[Val12]Ha-Ras的Cos细胞中Ras的法尼基化，IC50值在低微摩尔范围内。在这些浓度下，它们不抑制甾醇生物合成或蛋白的香叶基香叶基化。此外，我们观察到，当过量表达含有允许法尼基化（CVLS）或香叶基香叶基化（CVLL）的COOH末端序列的[Val12]活化形式的Ha-Ras时，Cos细胞会发生明显的形态变化，而过量表达缺乏异戊二烯化Cys的活化Ras（SVLS）时则不会。Ras诱导的形态变化可用洛伐他汀部分逆转。重要的是，SCH 44342可阻断[Val12]Ha-Ras-CVLS诱导的形态变化，但不能阻断[Val12]Ha-Ras-CVLL诱导的形态变化。最近，已报道了许多其他FPT抑制剂。据报道具有基于细胞活性的大多数化合物是CAAX底物的拟肽类似物。我们的FPT抑制剂的新颖之处在于，尽管它们在动力学实验中与Ras蛋白竞争，但它们本质上完全是非肽的，它们没有可氧化的巯基功能，并且在低微摩尔浓度下在细胞中具有活性。
