title: The tubulin-depolymerising agent combretastatin-4 induces ectopic aster assembly and mitotic catastrophe in lung cancer cells H460.
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.
authors.affiliation: Department of Biology, University Roma Tre, V.le Marconi 446, 00146, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cenciarelli
authors.forename: Caterina
authors.initials: C
authors.lastname: Tanzarella
authors.forename: Ilio
authors.initials: I
authors.lastname: Vitale
authors.forename: Claudio
authors.initials: C
authors.lastname: Pisano
authors.forename: Pasqualina
authors.initials: P
authors.lastname: Crateri
authors.forename: Stefania
authors.initials: S
authors.lastname: Meschini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Arancia
authors.forename: Antonio
authors.initials: A
authors.lastname: Antoccia
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002289:Carcinoma, Non-Small-Cell Lung; D045744:Cell Line, Tumor; D006801:Humans; D008175:Lung Neoplasms; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000187:drug effects* / Q000648:ultrastructure; D008938:Mitosis / Q000187:drug effects*; D013267:Stilbenes / Q000494:pharmacology*; D050257:Tubulin Modulators / Q000494:pharmacology*
chemical_list: D013267:Stilbenes; D050257:Tubulin Modulators; C058728:fosbretabulin