RAS CAAX PEPTIDOMIMETIC FTI-277 SELECTIVELY BLOCKS ONCOGENIC RAS SIGNALING BY INDUCING CYTOPLASMIC ACCUMULATION OF INACTIVE RAS-RAF COMPLEXES
RAS CAAX PEPTIDOMIMETIC FTI-277 SELECTIVELY BLOCKS ONCOGENIC RAS SIGNALING BY INDUCING CYTOPLASMIC ACCUMULATION OF INACTIVE RAS-RAF COMPLEXES
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DOI：
10.1074/jbc.270.45.26802
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发表时间：
1995-11-10
影响因子：
4.8
通讯作者：
SEBTI, SM
中科院分区：
文献类型：
--
作者：
LERNER, EC;QIAN, YM;SEBTI, SM
Ras诱导的恶性转化需要Ras法尼基化，法尼基转移酶（FTase）催化的脂质翻译后修饰。这种酶的抑制剂已被证明可以阻断Ras依赖性转化，但其发生机制在很大程度上仍然未知。我们已经设计了FTI-276，这是K-Ras 4 B的COOH末端Cys-Val-Ile-Met的肽模拟物，其在体外有效抑制FTase（IC 50 = 500 pM），并且对FTase的选择性高于香叶基香叶基转移酶I（GGT酶I）（IC 50 = 50 nM）。FTI-277是FTI-276的甲酯衍生物，在抑制H-Ras方面非常有效（IC 50 = 100 nM），但在全细胞中不能抑制香叶基香叶基化Rap 1A的加工。用FTI-277处理H-Ras癌基因转化的NIH 3 T3细胞，阻断了由法尼基化Ras（H-RasF）转化的细胞中丝氨酸/苏氨酸激酶c-Raf-1向质膜的募集和随后的激活，但不阻断香叶基香叶基化Ras（H-RasGG），FTI-277诱导细胞质非法尼基化的H-Ras的积累，其能够结合Raf并形成细胞质Ras/此外，FTI-277阻断H-RasF中丝裂原活化蛋白激酶（MAPK）的组成性活化，但不阻断H-RasGG或Raf-transformed细胞中丝裂原活化蛋白激酶（MAPK）的组成性活化。FTI-277还抑制致癌K-Ras 4 B加工和MAPK的组成性活化，但所需的浓度比H-Ras抑制所需的浓度高100倍。结果表明，FTI-277通过在细胞质中积累无活性的Ras/Raf复合物来阻断Ras致癌信号传导，从而防止MAPK级联的组成性激活。
Ras-induced malignant transformation requires Ras farnesylation, a lipid posttranslational modification catalyzed by farnesyltransferase (FTase). Inhibitors of this enzyme have been shown to block Ras-dependent transformation, but the mechanism by which this occurs remains largely unknown. We have designed FTI-276, a peptide mimetic of the COOH-terminal Cys-Val-Ile-Met of K-Ras4B that inhibited potently FTase in vitro (IC50 = 500 pM) and was highly selective for FTase over geranylgeranyltransferase I (GGTase I) (IC50 = 50 nM). FTI-277, the methyl ester derivative of FTI-276, was extremely potent (IC50 = 100 nM) at inhibiting H-Ras, but not the geranylgeranylated Rap1A processing in whole cells. Treatment of H-Ras oncogene-transformed NIH 3T3 cells with FTI-277 blocked recruitment to the plasma membrane and subsequent activation of the serine/threonine kinase c-Raf-1 in cells transformed by farnesylated Ras (H-RasF), but not geranylgeranylated, Ras (H-RasGG), FTI-277 induced accumulation of cytoplasmic non-farnesylated H-Ras that was able to bind Raf and form cytoplasmic Ras/Raf complexes in which Raf kinase was not activated, Furthermore, FTI-277 blocked constitutive activation of mitogen-activated protein kinase (MAPK) in H-RasF, but not H-RasGG, or Raf-transformed cells, FTI-277 also inhibited oncogenic K-Ras4B processing and constitutive activation of MAPK, but the concentrations required were 100-fold higher than those needed for H-Ras inhibition. The results demonstrate that FTI-277 blocks Ras oncogenic signaling by accumulating inactive Ras/Raf complexes in the cytoplasm, hence preventing constitutive activation of the MAPK cascade.