Eribulin Binds at Microtubule Ends to a Single Site on Tubulin To Suppress Dynamic Instability
Eribulin Binds at Microtubule Ends to a Single Site on Tubulin To Suppress Dynamic Instability
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DOI：
10.1021/bi901810u
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发表时间：
2010-02-16
期刊：
影响因子：
2.9
通讯作者：
Jordan, Mary Ann
中科院分区：
文献类型：
--
作者：
Smith, Jennifer A.;Wilson, Leslie;Jordan, Mary Ann
甲磺酸艾日布林 (E7389) 是海洋天然产物软海绵素 B 的合成类似物，目前正处于治疗癌症的 III 期临床试验中。艾日布林以微管为靶点，通过抑制微管生长来抑制微管正端的动态不稳定性，而对油缩短作用很小或没有影响[Jordan，M.A.等人。 (2005)摩尔。癌症治疗。 4、1086-1095]。使用[H-3]艾日布林，我们发现艾日布林在单个位点结合可溶性微管蛋白；然而，这种结合是复杂的，总体 K-d 为 46 μM，但也显示出对 25% 微管蛋白子集的真实或表观非常高的亲和力 (K-d = 0.4 μM)。艾日布林还结合微管，每个微管的最大化学计量为 14.7 +/- 1.3 个分子（K-d = 3.5 μM），强烈表明在微管末端存在相对高亲和力的结合位点。在100 nM（抑制微管加末端生长50%的浓度）下，我们发现每两个微管结合一个艾日布林分子，表明单个艾日布林分子在微管末端的结合可以有效抑制其生长。艾日布林不抑制微管负端的动态不稳定性。将微管与 2 或 4 μM 长春花碱预孵育可诱导额外的低亲和力艾日布林结合位点，最有可能位于张开的微管末端。总体而言，我们的结果表明艾日布林以高亲和力与微管正端结合，从而抑制动态不稳定性。
Eribulin mesylate (E7389), a synthetic analogue of the marine natural product halichondrin B, is in phase III clinical trials for the treatment of cancer. Eribulin targets microtubules, suppressing dynamic instability at microtubule plus ends through ail inhibition of microtubule growth With little or no effect oil shortening [Jordan, M.A., et al. (2005) Mol. Cancer Ther. 4, 1086-1095]. Using [H-3]eribulin, we found that eribulin binds soluble tubulin at a single site; however, this binding is complex with an overall K-d of 46 mu M, but also showing a real or apparent very high affinity (K-d = 0.4 mu M) for a subset of 25% of the tubulin. Eribulin also binds microtubules With a maximum stoichiometry of 14.7 +/- 1.3 molecules per microtubule (K-d = 3.5 mu M), strongly Suggesting the presence of a relatively high-affinity binding site at microtubule ends. At 100 nM, the concentration that inhibits microtubule plus end growth by 50%, we found that one molecule of eribulin is bound per two microtubules, Indicating that the binding of a single eribulin molecule at a microtubule end can potently inhibit its growth. Eribulin does not suppress dynamic instability at microtubule minus ends. Preincubation of microtubules with 2 or 4 mu M vinblastine induced additional lower-affinity eribulin binding sites, most likely at splayed microtubule ends. Overall, our results indicate that eribulin binds with high affinity to microtubule plus ends and thereby Suppresses dynamic instability.