ICRF-193, a catalytic inhibitor of DNA topoisomerase II, delays the cell cycle progression from metaphase, but not from anaphase to the G1 phase in mammalian cells

We have shown previously that ICRF-193, a catalytic inhibitor of DNA topoisomerase II (topo II), delays cell cycle progression in HeLa S3 cells, We report here that the delay of the transition in M phase is observed when HeLa S3 cells were treated with ICRF-193 during metaphase, but not thereafter, ICRF-193 also delayed the degradation of cyclin B in the transition from M to G1 phase, while in Chinese hamster ovary (CHO) cells the drug did not delay the progression in M phase, Since HeLa S3 and CHO cells are 'stringent' and 'relaxed' in mitotic control, respectively, it is suggested that under topo II inhibition, the M phase checkpoint operates through an inability for chromosome segregation. (C) 1997 Federation of European Biochemical Societies.