Structure-Activity Analysis of the Interaction of Curacin A, the Potent Colchicine Site Antimitotic Agent, with Tubulin and Effects of Analogs on the Growth of MCF-7 Breast Cancer Cells
作者:Pascal Verdier-Pinard、Jing-Yu Lai、Hae-Dong Yoo、Jurong Yu、Brian Marquez、Dale G. Nagle、Mitch Nambu、James D. White、J. R. Falck、William H. Gerwick、Billy W. Day、Ernest Hamel
DOI:10.1124/mol.53.1.62
日期:1998.1.1
Originally purified as a major lipid component of a strain of the cyanobacterium Lyngbya majuscula isolated in Curaçao, curacin A is a potent inhibitor of cell growth and mitosis, binding rapidly and tightly at the colchicine site of tubulin. Because its molecular structure differs so greatly from that of colchicine and other colchicine site inhibitors, we prepared a series of curacin A analogs to determine the important structural features of the molecule. These modifications include reduction and E -to- Z transitions of the olefinic bonds in the 14-carbon side chain of the molecule; disruption of and configurational changes in the cyclopropyl moiety; disruption, oxidation, and configurational reversal in the thiazoline moiety; configurational reversal and substituent modifications at C13; and demethylation at C10. Inhibitory effects on tubulin assembly, the binding of colchicine to tubulin, and the growth of MCF-7 human breast carcinoma cells were examined. The most important portions of curacin A required for its interaction with tubulin seem to be the thiazoline ring and the side chain at least through C4, the portion of the side chain including the C9–10 olefinic bond, and the C10 methyl group. Only two modifications totally eliminated the tubulin-drug interaction. The inactive compounds were a segment containing most of the side chain, including its two substituents, and analogs in which the methyl group at the C13 oxygen atom was replaced by a benzoate residue. Antiproliferative activity comparable with that observed with curacin A was only reproduced in compounds that were potent inhibitors of the binding of colchicine to tubulin. Molecular modeling and quantitative structure-activity relationship studies demonstrated that most active analogs overlapped extensively with curacin A but failed to provide an explanation for the apparent structural analogy between curacin A and colchicine.
最初从在库拉索岛分离出的蓝绿细菌Lyngbya majuscula中提纯的主要脂质成分Curacin A,是一种强有力的细胞生长和有丝分裂抑制剂,能快速而紧密地结合在微管蛋白的秋水仙碱位点。由于其分子结构与秋水仙碱及其他秋水仙碱位点抑制剂有很大差异,我们制备了一系列Curacin A的类似物以确定该分子的关键结构特征。这些修改包括减少和E到Z的烯烃键转变、环丙基部分的破坏和构象变化、噻唑啉部分的破坏、氧化和构象反转、C13的构象反转和取代基修饰以及在C10的去甲基化。我们考察了对微管蛋白组装、秋水仙碱与微管蛋白结合以及MCF-7人乳腺癌细胞生长的抑制效果。Curacin A与微管蛋白相互作用所需的最重要部分似乎是噻唑啉环以及至少通过C4的侧链部分、包括C9-10烯烃键的侧链部分和C10的甲基。只有两个修饰完全消除了微管蛋白-药物的相互作用。无活性化合物包括包含大部分侧链的片段及其两个取代基,以及将C13氧原子上的甲基替换为苯甲酸残基的类似物。只有在对微管蛋白结合的秋水仙碱具有强抑制作用的化合物中,才再现了与Curacin A相当的抗增殖活性。分子建模和定量构效关系研究表明,大多数活性类似物与Curacin A重叠广泛,但未能解释Curacin A与秋水仙碱之间明显的结构类比。