Wilson Leslie, Lopus Manu, Miller Herbert P, Azarenko Olga, Riffle Stephen, Smith Jennifer A, Jordan Mary Ann
Neuroscience Research Institute, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
Experimental Cancer Therapeutics and Chemical Biology, UM-DAE Centre for Excellence in Basic Sciences , Mumbai, India.
Biochemistry. 2015 Oct 27;54(42):6482-9. doi: 10.1021/acs.biochem.5b00745. Epub 2015 Oct 9.
Eribulin mesylate (Halaven) is a microtubule-targeted anticancer drug used to treat patients with metastatic breast cancer who have previously received a taxane and an anthracycline. It binds at the plus ends of microtubules and has been shown to suppress plus end growth selectively. Because the class III β tubulin isotype is associated with resistance to microtubule targeting drugs, we sought to determine how βIII tubulin might mechanistically influence the effects of eribulin on microtubules. We found that while [(3)H]eribulin bound to bovine brain soluble tubulin depleted of βIII tubulin in a manner similar to that of unfractionated tubulin, it bound to plus ends of microtubules that were depleted of βIII-depleted tubulin with a maximal stoichiometry (20 ± 3 molecules per microtubule) higher than that of unfractionated microtubules (9 ± 2 molecules per microtubule). In addition, eribulin suppressed the dynamic instability behavior of βIII-depleted microtubules more strongly than and in a manner different from that of microtubules containing βIII tubulin. Specifically, with βIII tubulin present in the microtubules, 100 nM eribulin suppressed the growth rate by 32% and marginally reduced the catastrophe frequency (by 17%) but did not modulate the rescue frequency. However, in the absence of βIII tubulin, eribulin not only reduced the growth rate but also strongly reduced the shortening rate (by 43%) and the catastrophe and the rescue frequencies (by 49 and 32%, respectively). Thus, when present in microtubules, βIII tubulin substantially weakens the effects of eribulin.
甲磺酸艾瑞布林（Halaven）是一种靶向微管的抗癌药物，用于治疗先前接受过紫杉烷类和蒽环类药物治疗的转移性乳腺癌患者。它结合在微管的正端，已被证明能选择性地抑制正端生长。由于III类β微管蛋白亚型与对微管靶向药物的耐药性有关，我们试图确定βIII微管蛋白可能如何在机制上影响艾瑞布林对微管的作用。我们发现，虽然[³H]艾瑞布林以与未分级微管蛋白类似的方式结合到去除了βIII微管蛋白的牛脑可溶性微管蛋白上，但它以比未分级微管（每根微管9±2个分子）更高的最大化学计量比（每根微管20±3个分子）结合到去除了βIII微管蛋白的微管正端。此外，艾瑞布林比含有βIII微管蛋白的微管更强烈且以不同方式抑制去除了βIII微管蛋白的微管的动态不稳定性行为。具体而言，当微管中存在βIII微管蛋白时，100 nM艾瑞布林将生长速率抑制了32%，并略微降低了灾难频率（降低了17%），但未调节挽救频率。然而，在没有βIII微管蛋白的情况下，艾瑞布林不仅降低了生长速率，还强烈降低了缩短速率（降低了43%）以及灾难频率和挽救频率（分别降低了49%和32%）。因此，当存在于微管中时，βIII微管蛋白会显著削弱艾瑞布林的作用。
