title: Combretastatin CA-4 and combretastatin derivative induce mitotic catastrophe dependent on spindle checkpoint and caspase-3 activation in non-small cell lung cancer cells.
abstract: Combretastatin A-4 (CA-4), a natural stilbenoid isolated from Combretum caffrum, is a new vascular targeting agent (VTA) known for its antitumor activity due to its anti-tubulin properties. We investigated the molecular mechanisms leading to cell death in non-small cell lung cancer H460 cells induced by natural (CA-4) and synthetic stilbenoids (ST2151) structurally related to CA-4. We found that both compounds induced depolymerization and rearrangement of spindle microtubules, as well as an increasingly aberrant organization of metaphase chromosomes in a dose- and time-dependent manner. Prolonged exposition to ST2151 led cells to organize multiple sites of tubulin repolymerization, whereas tubulin repolymerization was observed only after CA-4 washout. H460 cells were arrested at a pro-metaphase stage, with condensed chromosomes and a triggered spindle assembly checkpoint, as evaluated by kinetochore localization of Bub1 and Mad1 antibodies. Persistent checkpoint activation led to mitochondrial membrane permeabilization (MMP) alterations, cytochrome c release, activation of caspase-9 and -3, PARP cleavage and DNA fragmentation. On the other hand, caspase-2, and -8 were not activated by the drug treatment. The ability of cells to reassemble tubulin in the presence of an activated checkpoint may be responsible for ST2151-induced multinucleation, a recognized sign of mitotic catastrophe. In conclusion, we believe that discovery of new agents able to trigger mitotic catastrophe cell death as a result of mitotic block and prolonged spindle checkpoint activation is particularly worthwhile, considering that tumor cells have a high proliferative rate and mitotic failure occurs irrespective of p53 status.
authors.affiliation: Department of Biology, University Roma Tre, V.le Marconi 446, 00146, Rome, Italy.
authors.forename: Ilio
authors.initials: I
authors.lastname: Vitale
authors.forename: Antonio
authors.initials: A
authors.lastname: Antoccia
authors.forename: Chiara
authors.initials: C
authors.lastname: Cenciarelli
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: Claudio
authors.initials: C
authors.lastname: Pisano
authors.forename: Caterina
authors.initials: C
authors.lastname: Tanzarella
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects*; D008941:Spindle Apparatus / Q000187:drug effects / Q000473:pathology; D013267:Stilbenes / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D013267:Stilbenes; D045304:Cytochromes c; C505407:CASP3 protein, human; D053148:Caspase 3; C058728:fosbretabulin