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

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 proteinlabeled 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 Â mitotic IC 50 ), 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 Â IC 50 (4 nmol/L), mitotic arrest also occurred in concert with suppressed centromere dynamics. Although media IC 50 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.

Eribulin Induces Irreversible Mitotic Blockade: Implications of Cell-Based Pharmacodynamics for In vivo Efficacy under Intermittent Dosing Conditions

“…Studies by Alday and Correia (26) showed that ER-076349, but not eribulin, enhances tubulin self-association into oligomers by binding at or near interdimer interfaces, suggesting that ER-076349 can associate with existing oligomers, including microtubule sides. This would dramatically increase the number of intracellular binding sites for ER-076349 relative to eribulin, and explain both our findings and those of Okouneva and colleagues (14) ]ER-076349. Thus, although eribulin would bind to lower numbers of intracellular sites than ER-076349, its overall binding affinity would be greater, resulting in slower off-rates and more persistent postwashout retention.…”

“…Eribulin works via apoptosis-inducing, microtubule-targeting antimitotic mechanisms (10,12) involving inhibition of microtubule dynamics by mechanisms distinct from most other tubulin-targeting agents (13)(14)(15). Eribulin's mechanistic novelty is noteworthy when considering the original mechanistic studies on HB, which showed it to have a spectrum of biochemical effects on tubulin that was distinct from other tubulin-targeted drugs (16).…”

Chemoinformatic Expedition of the Chemical Space of Fungal Products

“…There are also a few remarkable drugs from marine sources, such as the recently approved anticancer drug eribulin, a synthetic analog of halichondrin B isolated from the sponge Halichondria okadai [4]. In the microbial area the main sources have been terrestrial actinomycetes and fungi.…”

Antiproliferative Mechanism of Action of the Novel Taxane Cabazitaxel as Compared with the Parent Compound Docetaxel in MCF7 Breast Cancer Cells

“…4H, P < 0.001). 14 C]-docetaxel (-}-) in MCF7 cells over time was determined as described (36). Docetaxel was taken up relatively slowly, attaining an intracellular concentration of 25 mmol/L after 10 hours, and remaining at approximately that level for the next 20 hours (Fig.…”