A novel microtubule-modulating noscapinoid triggers apoptosis by inducing spindle multipolarity via centrosome amplification and declustering

Cell Death Differ. 2011 Apr;18(4):632-44. doi: 10.1038/cdd.2010.133. Epub 2010 Nov 5.


We have previously shown that a non-toxic noscapinoid, EM011 binds tubulin without altering its monomer/polymer ratio. EM011 is more active than the parent molecule, noscapine, in inducing G2/M arrest, inhibiting cellular proliferation and tumor growth in various human xenograft models. However, the mechanisms of mitotic-block and subsequent cell death have remained elusive. Here, we show that EM011-induced attenuation of microtubule dynamics was associated with impaired association of microtubule plus-end tracking proteins, such as EB1 and CLIP-170. EM011 treatment then led to the formation of multipolar spindles containing 'real' centrioles indicating drug-induced centrosome amplification and persistent centrosome declustering. Centrosome amplification was accompanied by an upregulation of Aurora A and Plk4 protein levels, as well as a surge in the kinase activity of Aurora A, suggesting a deregulation of the centrosome duplication cycle. Cell-cycle phase-specific experiments showed that the 'cytotoxicity-window' of the drug encompasses the late S-G2 period. Drug-treatment, excluding S-phase, not only resulted in lower sub-G1 population but also attenuated centrosome amplification and spindle multipolarity, suggesting that drug-induced centrosome amplification is essential for maximal cell death. Subsequent to a robust mitotic arrest, EM011-treated cells displayed diverse cellular fates suggesting a high degree of intraline variation. Some 'apoptosis-evasive' cells underwent aberrant cytokinesis to generate rampant aneuploidy that perhaps contributed to drug-induced cell death. These data indicate that spindle multipolarity induction by means of centrosome amplification has an exciting chemotherapeutic potential that merits further investigation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Apoptosis*
  • Aurora Kinases
  • Cell Line, Tumor
  • Centrosome / physiology*
  • Dioxoles / pharmacology*
  • G1 Phase
  • G2 Phase
  • Humans
  • Isoquinolines / pharmacology*
  • Microtubule-Associated Proteins / metabolism
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Mitosis
  • Neoplasm Proteins / metabolism
  • Protein-Serine-Threonine Kinases / metabolism
  • S Phase
  • Spindle Apparatus / physiology*
  • Tubulin Modulators / pharmacology*
  • Up-Regulation


  • Dioxoles
  • EM011 compound
  • Isoquinolines
  • MAPRE1 protein, human
  • Microtubule-Associated Proteins
  • Neoplasm Proteins
  • Tubulin Modulators
  • cytoplasmic linker protein 170
  • PLK4 protein, human
  • Aurora Kinases
  • Protein-Serine-Threonine Kinases