2-methoxyestradiol suppresses microtubule dynamics and arrests mitosis without depolymerizing microtubules
2-methoxyestradiol suppresses microtubule dynamics and arrests mitosis without depolymerizing microtubules
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DOI：
10.1158/1535-7163.mct-06-0113
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发表时间：
2006-09-01
影响因子：
5.7
通讯作者：
Jordan, Mary Ann
中科院分区：
文献类型：
--
作者：
Kamath, Kathy;Okouneva, Tatiana;Jordan, Mary Ann
2-甲氧基雌二醇（2 ME 2）是雌二醇-17 β的代谢产物，是一种新型的抗有丝分裂和抗血管生成药物候选药物，在I期和II期临床试验中用于治疗广泛的肿瘤类型。2 ME 2在秋水仙碱位点处或附近与微管蛋白结合，并在体外抑制微管蛋白的聚合，这表明它可能通过干扰正常微管功能而起作用。然而，微管解聚在其抗肿瘤作用机制中的作用一直存在争议。为了确定2 ME 2诱导有丝分裂阻滞的机制，我们分析了其对微管聚合的影响，以及其对体外和活MCF 7细胞的动态不稳定性的影响。在体外，2 ME 2（5-100 μ mol/L）以浓度依赖性方式抑制纯化的微管蛋白的组装，在200 μ mol/L 2 ME 2时抑制最大（60%）。然而，与微管相关的含蛋白的微管，需要显着更高的2 ME 2浓度去微管，和聚合物的质量仅减少了13%，在500 μ mol/L的2 ME 2。在体外，动态不稳定性在较低浓度下被抑制。4 μ mol/L的2 ME 2使细胞的平均生长速率降低17%，活力降低27%。在有丝分裂停滞IC 50（1.2 μ mol/L）的活间期MCF 7细胞中，2 ME 2显着抑制平均微管生长速率、持续时间和长度以及总体动态性，与其体外作用一致，并且没有任何可观察到的微管解聚。两者合计，结果表明，在最低有效浓度的2 ME 2有丝分裂阻滞的主要机制是抑制微管动力学，而不是微管解聚本身。
2-Methoxyestradiol (2ME2), a metabolite of estradiol-17 beta, is a novel antimitotic and antiangiogenic drug candidate in phase I and II clinical trials for the treatment of a broad range of tumor types. 2ME2 binds to tubulin at or near the colchicine site and inhibits the polymerization of tubulin in vitro, suggesting that it may work by interfering with normal microtubule function. However, the role of microtubule depolymerization in its antitumor mechanism of action has been controversial. To determine the mechanism by which 2ME2 induces mitotic arrest, we analyzed its effects on microtubule polymerization in vitro and its effects on dynamic instability both in vitro and in living MCF7 cells. In vitro, 2ME2 (5-100 mu mol/L) inhibited assembly of purified tubulin in a concentration-dependent manner, with maximal inhibition (60%) at 200 mu mol/L 2ME2. However, with microtubule-associated protein-containing microtubules, significantly higher 2ME2 concentrations were required to depolymerize microtubules, and polymer mass was reduced by only 13% at 500 mu mol/L 2ME2. In vitro, dynamic instability was inhibited at lower concentrations. Specifically, 4 mu mol/L 2ME2 reduced the mean growth rate by 17% and dynamicity by 27%. In living interphase MCF7 cells at the IC50 for mitotic arrest (1.2 mu mol/L), 2ME2 significantly suppressed the mean microtubule growth rate, duration and length, and the overall dynamicity, consistent with its effects in vitro, and without any observable depolymerization of microtubules. Taken together, the results suggest that the major mechanism of mitotic arrest at the lowest effective concentrations of 2ME2 is suppression of microtubule dynamics rather than microtubule depolymerization per se.