Dabydeen Donnette A, Florence Gordon J, Paterson Ian, Hamel Ernest
Screening Technologies Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
Cancer Chemother Pharmacol. 2004 May;53(5):397-403. doi: 10.1007/s00280-003-0755-0. Epub 2004 Jan 22.
To determine whether inhibitors of microtubule assembly inhibit polymerization induced by discodermolide and epothilone B, as well as paclitaxel, and to quantitatively measure such effects.
Inhibition was quantitated by measuring polymer formation either by turbidimetry or by centrifugation, and the amount of inhibitor required to inhibit 50% relative to an appropriate control reaction was determined.
The inhibitory drugs evaluated were four colchicine site agents (combretastatin A-4, podophyllotoxin, nocodazole, and N-acetylcolchinol- O-methyl ether), maytansine, which competitively inhibits the binding of Catharanthus alkaloids to tubulin, halichondrin B and phomopsin A, which noncompetitively inhibit the binding of Catharanthus alkaloids to tubulin, and the depsipeptide dolastatin 15. While relative inhibitory effects were highly variable, a few broad generalizations can be made. First, assembly reactions that were either enhanced or dependent upon all three stimulatory drugs were subject to inhibition by all inhibitors. Second, the more readily the tubulin assembled, the greater the concentration of inhibitor required to inhibit polymerization. Drug IC50 values were generally lowest with no stimulatory drug and highest when discodermolide was present; IC50 values were higher as reaction temperature increased; and IC50 values were higher as the tubulin concentration increased. Third, inhibition of assembly by inhibitors of Catharanthus alkaloid binding to tubulin changed much less as a function of changes in reaction conditions than inhibition by inhibitors of colchicine binding.
Since there was no apparent quantitative predictability of combined drug interactions with tubulin, any combination of interest must be studied in detail.
确定微管组装抑制剂是否能抑制由盘状软骨素、埃坡霉素B以及紫杉醇诱导的聚合反应，并对这些效应进行定量测定。
通过比浊法或离心法测量聚合物形成来对抑制作用进行定量，并确定相对于适当对照反应抑制50%所需的抑制剂用量。
所评估的抑制性药物包括四种秋水仙碱位点药物（康普瑞他汀A - 4、鬼臼毒素、诺考达唑和N - 乙酰秋水仙碱 - O - 甲基醚）、可竞争性抑制长春花生物碱与微管蛋白结合的美登素、非竞争性抑制长春花生物碱与微管蛋白结合的软海绵素B和腐草霉素A，以及环肽多拉司他汀15。虽然相对抑制效应变化很大，但可以得出一些广泛的一般性结论。首先，所有三种刺激药物增强或依赖的组装反应都受到所有抑制剂的抑制。其次，微管蛋白组装越容易，抑制聚合所需的抑制剂浓度就越高。在没有刺激药物时药物的半数抑制浓度（IC50）值通常最低，而在存在盘状软骨素时最高；IC50值随反应温度升高而升高；IC50值也随微管蛋白浓度升高而升高。第三，长春花生物碱与微管蛋白结合抑制剂对组装的抑制作用随反应条件变化的改变程度远小于秋水仙碱结合抑制剂的抑制作用。
由于药物与微管蛋白的联合相互作用没有明显的定量可预测性，任何感兴趣的组合都必须进行详细研究。
