The tubulin-depolymerising agent combretastatin-4 induces ectopic aster assembly and mitotic catastrophe in lung cancer cells H460

Apoptosis. 2008 May;13(5):659-69. doi: 10.1007/s10495-008-0200-2.

Abstract

The relationship between microtubular dynamics, dismantling of pericentriolar components and induction of apoptosis was analysed after exposure of H460 non-small lung cancer cells to anti-mitotic drugs. The microtubule destabilising agent, combretastatin-A4 (CA-4) led to microtubular array disorganization, arrest in mitosis and abnormal metaphases, accompanied by the presence of numerous centrosome-independent "star-like" structures containing tubulin and aggregates of pericentrosomal matrix components like gamma-tubulin, pericentrin and ninein, whereas the structural integrity of centrioles was not affected by treatment. On the contrary, in condition of prolonged exposure or high concentrations of CA-4 such aggregates never formed. Treatment with 7.5 nM CA-4, which produced a high frequency "star-like" aggregates, was accompanied by mitotic catastrophe commitment characterized by translocation of the proapoptotic Bim protein to mitochondria activation of caspases-3/9 and DNA fragmentation as a result of either prolonged metaphase arrest or attempt of cells to divide. Drug concentrations which fail to block cells at mitosis were also unable to activate apotosis. A detailed time-course analysis of cell cycle arrest and apoptosis indicated that after CA-4 washout the number of metaphases with "star-like" structures decreased as a function of time and arrested cells proceeded in anaphase. After 4 h, the multiple alpha- and gamma-tubulin aggregates coalesced into two well-defined spindles in a bipolar mitotic spindle organization. Overall, our findings suggest that the maintenance of microtubular integrity plays a relevant role in stabilising the pericentriolar matrix, whose dismantling can be associated with apoptosis after exposure to microtubule depolymerising agents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Carcinoma, Non-Small-Cell Lung
  • Cell Line, Tumor
  • Humans
  • Lung Neoplasms
  • Microscopy, Confocal
  • Microscopy, Electron, Transmission
  • Microtubules / drug effects*
  • Microtubules / ultrastructure
  • Mitosis / drug effects*
  • Stilbenes / pharmacology*
  • Tubulin Modulators / pharmacology*

Substances

  • Stilbenes
  • Tubulin Modulators
  • fosbretabulin