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Research Articles: Therapeutics, Targets, and Development

Inhibition of centromere dynamics by eribulin (E7389) during mitotic metaphase

¹ Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California and ² Eisai Research Institute, Andover, Massachusetts

Requests for reprints: Mary Ann Jordan, Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106. Phone: 805-893-5317; Fax: 805-893-4724. E-mail: jordan{at}lifesci.ucsb.edu

Abstract

Eribulin (E7389), a synthetic analogue of halichondrin B in phase III clinical trials for breast cancer, binds to tubulin and microtubules. At low concentrations, it suppresses the growth phase of microtubule dynamic instability in interphase cells, arrests mitosis, and induces apoptosis, suggesting that suppression of spindle microtubule dynamics induces mitotic arrest. To further test this hypothesis, we measured the effects of eribulin on dynamics of centromeres and their attached kinetochore microtubules by time-lapse confocal microscopy in living mitotic U-2 OS human osteosarcoma cells. Green fluorescent protein–labeled centromere-binding protein B marked centromeres and kinetochore-microtubule plus-ends. In control cells, sister chromatid centromere pairs alternated under tension between increasing and decreasing separation (stretching and relaxing). Eribulin suppressed centromere dynamics at concentrations that arrest mitosis. At 60 nmol/L eribulin (2 x mitotic IC₅₀), the relaxation rate was suppressed 21%, the time spent paused increased 67%, and dynamicity decreased 35% (but without reduction in mean centromere separation), indicating that eribulin decreased normal microtubule-dependent spindle tension at the kinetochores, preventing the signal for mitotic checkpoint passage. We also examined a more potent, but in tumors less efficacious antiproliferative halichondrin derivative, ER-076349. At 2 x IC₅₀ (4 nmol/L), mitotic arrest also occurred in concert with suppressed centromere dynamics. Although media IC₅₀ values differed 15-fold between the two compounds, the intracellular concentrations were similar, indicating more extensive relative uptake of ER-076349 into cells compared with eribulin. The strong correlation between suppression of kinetochore-microtubule dynamics and mitotic arrest indicates that the primary mechanism by which eribulin blocks mitosis is suppression of spindle microtubule dynamics. [Mol Cancer Ther 2008;7(7):2003–11]

Grant support: Eisai Research Institute and NIH grant CA 57291.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

³ J. Smith, L. Wilson, and M.A. Jordan, unpublished data.

Received 1/28/08; revised 4/25/08; accepted 5/ 7/08.