Inhibition of Prenylated Protein Processing

Ras家族的成员与许多人类癌症有关，它们在发病后被修饰，靶向它们， 合适的细胞内位置。Ras和其他-CaaX蛋白经历三个连续反应： 半胱氨酸的异戊二烯化，特别是通过法尼基转移酶（FTase）的法尼基化; 末端氨基酸（-aaX）;和异戊二烯化半胱氨酸的α-羧基甲基化。这个过程是 对于膜定位和关键Ras癌蛋白的活性至关重要。FTase抑制剂正在 在临床试验中被评估为癌症化疗剂。不幸的是，这些化合物 令人惊讶的是，对许多Ras转化的肿瘤几乎没有影响。现在人们对随后的 酶促步骤;通过Ras转化酶（Reel）进行蛋白水解和通过异戊二烯基半胱氨酸进行α-羧基甲基化 甲基转移酶（Icmt）作为抑制Ras蛋白作用的替代靶标。羧基甲基化是 对于Ras蛋白在酵母和小鼠细胞中的正确定位至关重要。鉴于这一重要发现，我们 认为Icmt代表了化疗干预的极好靶点。我们假设 某些容易合成的类异戊二烯基ICMT抑制剂将是有价值的先导化合物 用于开发抗Ras癌症化疗剂。最近出版和未出版 我们实验室的研究已经证明，对氨基修饰和氨基修饰的修饰都是有效的。 异戊烯基半胱氨酸类异戊二烯单元可提供小分子Icmt抑制剂。具体目标是 合作，跨学科的研究建议如下：目的1）新的法尼醇类似物将是 通过固相合成方案将其加工成相应的异戊二烯基半胱氨酸衍生物。这些将 然后进行进一步的化学修饰以提供异戊二烯基半胱氨酸衍生物的文库。（2）这些 异戊二烯基半胱氨酸衍生物将作为潜在的ICMT抑制剂，使用高通量体外试验进行检测 系统和良好表征的和稳健的单点测定程序的ICMT活性。目标3） 评价异戊二烯基半胱氨酸类似物在体内阻断异戊二烯基半胱氨酸甲基化的能力。 将评价有效的细胞渗透性抑制剂错误定位Ras、干扰Ras的能力。 介导的信号传导，阻断胰腺导管癌的锚定非依赖性生长，并阻断肿瘤 体内生长

Members of the Ras family, implicated in many human cancers, are modified post-translationally, targeting them to the appropriate intracellular location. Ras and other -CaaX proteins undergo three sequential reactions: isoprenylation of the cysteine, in particular farnesylation by farnesyltransferase (FTase); proteolysis of the three terminal amino acids (-aaX); and a-carboxyl methylation of the isoprenylated cysteine. This process is crucial for membrane localization and thus activity of the key Ras oncoproteins. FTase inhibitors are being evaluated in clinical trials as cancer chemotherapeutic agents. Unfortunately, these compounds have surprisingly little effect on many Ras-transformed tumors. There is now growing interest in the subsequent enzymatic steps; proteolysis by Ras converting enzyme (Reel) and a-carboxyl methylation by isoprenylcysteine methyltransferase (Icmt) as alternative targets for the inhibition of Ras protein action. Carboxyl methylation is critical for the proper localization of Ras proteins in yeast and mouse cells. Given this important finding, we believe that Icmt represents an excellent target for chemotherapeutic intervention. We hypothesize that certain readily synthesized, isoprenoid-based inhibitors of Icmt will be valuable lead compounds for the development of anti-Ras cancer chemotherapeutic agents. Recent published and unpublished studies from our laboratories have demonstrated that modifications to both the amino modification and the isoprenoid unit ofprenylcysteines can afford small-molecule inhibitors of Icmt. The specific aims of this collaborative, interdisciplinary research proposal are as follows: Aim 1) Novel farnesol analogs will be elaborated to the corresponding prenylcysteine derivatives, via a solid-phase synthetic protocol. These will then undergo further chemical modification to provide libraries of prenylcysteine derivatives. Aim 2) These prenylcysteine derivatives will be assayed as potential inhibitors of Icmt, using high-throughput in vitro assay systems and well-characterized and robust single point assay procedures for Icmt activity. Aim 3) The prenylcysteine analogues will be evaluated for their ability to block prenylcysteine methylation in vivo. Potent cell permeable inhibitors will be evaluated for their ability to mislocalize Ras, interfere with Ras- mediated signaling, block anchorage-independent growth of pancreatic ductal carcinoma, and block tumor growth in vivo.