Honore Stéphane, Kamath Kathy, Braguer Diane, Wilson Leslie, Briand Claudette, Jordan Mary Ann
UMR-CNRS 6032, Université de la Méditerranée, Marseille, France.
Mol Cancer Ther. 2003 Dec;2(12):1303-11.
Discodermolide is a new microtubule-targeted drug in Phase I clinical trials that inhibits tumor growth and induces G(2)-M cell cycle arrest. It is effective against paclitaxel-resistant cell lines and acts synergistically in combination with paclitaxel. Suppression of microtubule dynamics by microtubule-targeted drugs has been hypothesized to be responsible for their ability to inhibit mitotic progression and cell proliferation. To determine whether discodermolide blocks mitosis by an effect on microtubule dynamics, we analyzed the effects of discodermolide on microtubule dynamics in living A549 human lung cancer cells during interphase at concentrations that block mitosis and inhibit cell proliferation. We found that discodermolide (7-166 nM) significantly suppressed microtubule dynamic instability. At the IC(50) for proliferation (7 nM discodermolide, 72 h), overall dynamicity was reduced by 23%. The principal parameters of dynamic instability suppressed by discodermolide were the microtubule shortening rate and length shortened. In addition, discodermolide markedly increased the frequency of rescued catastrophes. At the discodermolide concentration that resulted in 50% of maximal mitotic block (83 nM, 20 h), most microtubules were completely non-dynamic, no anaphases occurred, and all spindles were abnormal. The dynamicity of the remaining dynamic microtubules was reduced by 62%. The results indicate that a principal mechanism of inhibition of cell proliferation and mitotic block by discodermolide is suppression of microtubule dynamics. Importantly, the results indicate significant additional stabilizing effects of discodermolide on microtubule dynamics as compared with those of paclitaxel that may in turn reflect differences in their binding sites and their effects on tubulin conformation.
Discodermolide是一种正在进行I期临床试验的新型微管靶向药物，它能抑制肿瘤生长并诱导G(2)-M期细胞周期停滞。它对紫杉醇耐药细胞系有效，且与紫杉醇联合使用时具有协同作用。微管靶向药物对微管动力学的抑制作用被认为是其抑制有丝分裂进程和细胞增殖能力的原因。为了确定Discodermolide是否通过影响微管动力学来阻断有丝分裂，我们分析了Discodermolide在间期对活的A549人肺癌细胞微管动力学的影响，所用浓度能阻断有丝分裂并抑制细胞增殖。我们发现Discodermolide（7 - 166 nM）显著抑制微管动态不稳定性。在增殖的IC(50)（7 nM Discodermolide，72小时）时，整体动态性降低了23%。Discodermolide抑制的动态不稳定性的主要参数是微管缩短速率和缩短长度。此外，Discodermolide显著增加了挽救灾难的频率。在导致50%最大有丝分裂阻滞的Discodermolide浓度（83 nM，20小时）下，大多数微管完全无动态，没有后期发生，所有纺锤体均异常。其余动态微管的动态性降低了62%。结果表明，Discodermolide抑制细胞增殖和有丝分裂阻滞的主要机制是抑制微管动力学。重要的是，结果表明与紫杉醇相比，Discodermolide对微管动力学具有显著的额外稳定作用，这可能反过来反映了它们结合位点的差异以及对微管蛋白构象的影响。
