Mitotic cell death in BEL-7402 cells induced by enediyne antibiotic lidamycin is associated with centrosome overduplication.

Abstract

Mitotic cell death has been focused on in tumor therapy. However, the precise mechanisms underlying it remain unclear. We have reported previously that enediyne antibiotic lidamycin induces mitotic cell death at low concentrations in human epithelial tumor cells. The aim of this study was to investigate the possible link between centrosome dynamics and lidamycin-induced mitotic cell death in human hepatoma BEL-7402 cells. Growth curve was established by MTT assay. Cell multinucleation was detected by staining with Hoechst 33342. Flow cytometry was used to analyze cell cycle. Aberrant centrosomes were detected by indirect immunofluorescence. Western blot and senescence-associated beta-galactosidase (SA-beta-gal) staining were used to analyze protein expression and senescence-like phenotype, respectively. Exposure of BEL-7402 cells to a low concentration of lidamycin resulted in an increase in cells containing multiple centrosomes in association with the appearance of mitotic cell death and activation of SA-beta-gal in some cells, accompanied by the changes of protein expression for the regulation of proliferation and apoptosis. The mitochondrial signaling pathway, one of the major apoptotic pathways, was not activated during mitotic cell death. The aberrant centrosomes contributed to the multipolar mitotic spindles formation, which might lead to an unbalanced division of chromosomes and mitotic cell death characterized by the manifestation of multi- or micronucleated giant cells. Cell cycle analysis revealed that the lidamycin treatment provoked the retardation at G2/M phase, which might be involved in the centrosome overduplication. Mitotic cell death and senescence can be induced by treatment of BEL-7402 cells with a low concentration of lidamycin. Centrosome dysregulation may play a critical role in mitotic failure and ultimate cell death following exposure to intermediate dose of lidamycin.