Inhibition of DNA topoisomerase II by ICRF-193 induces polyploidization by uncoupling chromosome dynamics from other cell cycle events.

Abstract

Abstract. , a novel noncleavable, complexstabilizing type topoisomerase (topo) II inhibitor, has been shown to target topo II in mammalian cells (Ishida, R., T. Miki, T. Narita, R. Yui, S. Sato, K. R. Utsumi, K. Tanabe, and T. Andoh. 1991. Cancer Res. 51:4909--4916). With the aim of elucidating the roles of topo II in mammalian cells, we examined the effects of ICRF-193 on the transition through the S phase, when the genome is replicated, and through the M phase, when the replicated genome is condensed and segregated. Replication of the genome did not appear to be affected by the drug because the scheduled synthesis of DNA and activation of cdc2 kinase followed by increase in mitotic index occurred normally, while VP-16, a cleavable, complex-stabilizing type topo II inhibitor, inhibited all these processes. In the M phase, however, late stages of chromosome condensation and segregation were clearly blocked by . Inhibition at the stage of compaction of 300-nm diameter chromatin fibers to 600-nm diameter chromatids was demonstrated using the drug during premature chromosome condensation (PCC) induced in tsBN2 baby hamster kidney cells in early S and G2 phases. In spite of interference with M phase chromosome dynamics, other mitotic events such as activation of ode2 kinase, spindle apparatus reorganization and disassembly and re, assembly of nuclear envelopes occurred, and the cells traversed an unusual M phase termed "absence of chromosome segregation" (ACS)-M phase. Cells then continued through further cell cycle rounds, becoming polyploid and losing viability. This effect of ICRF-193 on the cell cycle was shown to parallel that of inactivation of topo II on the cell cycle of the ts top2 mutant yeast. The results strongly suggest that the essential roles of topo II are confined to the M phase, when the enzyme decatenates intertwined replicated chromosomes. In other phases of the cycle, including the S phase, topo II may thus play a complementary role with topo I in controlling the torsional strain accumulated in various genetic processes. topoisomerases (topo) t have been implicated in e maintenance of genetic processes such as repliation, transcription, and recombination by controlling the higher order chromosomal structure through the cell cycle (for review, see Wang, , 1987Cozzarelli and Address all correspondence to Ryoji Ishida,

Construction, Characterization, and Complementation of a Conditional-Lethal DNA Topoisomerase IIα Mutant Human Cell Line

“…Studies in a variety of systems indicate that topoII is essential for cellular viability and that it plays a key role in chromosome segregation. Thus, the abnormal cell divisions seen in yeast top2 mutants (Holm et al, 1985;Uemura and Yanagida, 1986), and in vertebrate cells treated with topoII inhibitors (Downes et al, 1991;Ishida et al, 1991Ishida et al, , 1994Haraguchi et al, 2000) are consistent with the unique ability of topoII to resolve the sister chromatids catenations generated when DNA replication forks meet (Wang, 2002). TopoII has been implicated in mammalian centromere function (Floridia et al, 2000;Spence et al, 2002), and it has been suggested that topoII in yeast may play a role in centromeric chromatin structure (Bachant et al, 2002).…”

“…In vitro studies of chromosome condensation in mitotic extracts (Newport and Spann, 1987;Adachi et al, 1991;Hirano and Mitchison, 1991, 1993), in which topoII is immunodepleted or inactivated by inhibitors, showed varying requirements for topoII. In the absence of suitable topoII mutants, in vivo studies in higher eukaryotes have made use of topoII inhibitors (Andoh et al, 1993;Downes et al, 1994;Gorbsky, 1994;Ishida et al, 1994;Gimenez-Abian et al, 1995;Andreassen et al, 1997;Gimenez-Abian et al, 2000) or RNA interference (Chang et al, 2003;Sakaguchi and Kikuchi, 2004). Such studies mostly support a role for topoII in chromosome condensation, but again, condensation was impaired to varying degrees, and in some cases (Andreassen et al, 1997;Chang et al, 2003;Sakaguchi and Kikuchi, 2004) impairment was surprisingly mild or absent.…”

Genistein inhibits Brca1 mutant tumor growth through activation of DNA damage checkpoints, cell cycle arrest, and mitotic catastrophe

“…23 Therefore, we hypothesized that topoisomerase II inhibitor activity in genistein could cause abnormal chromosome segregation and polyploidy. To investigate this, we treated cells with ICRF-193, which specifically inhibits topoisomerse II activity without causing DNA chain breaks.…”

The decatenation checkpoint

“…Chromosome breakage and nondisjunction at anaphase leads to chromosome translocations and other aberrations in daughter cells. These chromosome imbalances have been observed in several cell types following bisdioxopiperazine inhibition of topo II (Gorbsky, 1994;Ishida et al, 1994;Deming et al, 2002;Damelin et al, 2005). The spindle checkpoint would be expected to prevent anaphase after failure or bypass of the decatenation checkpoint.…”