Record Display for the EPA National Library Catalog


Main Title New Action for Topoisomerase Inhibitors.
Author Zucker, R. M. ; Elstein, K. H. ;
CORP Author ManTech Environmental Technology, Inc., Research Triangle Park, NC.;Health Effects Research Lab., Research Triangle Park, NC.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-91/242;
Stock Number PB92-110451
Additional Subjects Enzyme inhibitors ; DNA topoisomerase I ; Camptothecin ; Cell cycle ; Biosynthesis ; DNA replication ; Acute erythroblastic leukemia ; Cultured tumor cells ; Ploidies ; Flow cytometry ; Mice ; Chromosomes ; Reprints ;
Library Call Number Additional Info Location Last
NTIS  PB92-110451 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 12p
Topoisomerases are known to aid DNA replication by breaking and resealing supercoiled DNA. Consequently, cells exposed to topoisomerase inhibitors before or during the S (DNA synthetic) phase of the cell cycle undergo abnormal DNA replication and become irreversibly blocked in the G2 (pre-mitosis) phase. The authors report that following a 4-h exposure to topoisomerase II inhibitors, murine erythroleukemic cells (MELC) do not form mitotic figures but exhibit a time-dependent progression into G2 (4N DNA) and > G2 (up to 8N DNA) stages of the cell cycle. Following exposure to the topoisomerase I inhibitor camptothecin, recovering MELC also exhibit > G2 polyploidy, but to a considerably lesser degree: mitotic figures are present and a subpopulation of cells resumes cycling. However, both topo I and topo II inhibitors induce maximal percentages of > G2 cells when synchronized MELC are in the G2/M phase at the time of exposure. This suggests that, in addition to their S-phase action, topoisomerase inhibitors can interfere with chromosome condensation during G2 and, in so doing, induce polyploidy. (Copyright (c) 1991 Elsevier Scientific Publishers Ireland Ltd.)