title: Inhibition of intracellular topoisomerase II by antitumor bis(2,6-dioxopiperazine) derivatives: mode of cell growth inhibition distinct from that of cleavable complex-forming type inhibitors.
abstract: In the accompanying paper (K. Tanabe, Y. Ikegami, R. Ishida, and T. Andoh, Cancer Res., 51: 4903-4908, 1991), we showed that ICRF-154 and -193, dioxopiperazine derivatives, inhibited the activity of purified topoisomerase II, without formation of a cleavable DNA-protein complex. In order to see whether ICRF-154 and ICRF-193 affect cellular topoisomerase II in situ or not, we examined the effect of these drugs on etoposide (VP-16)-induced, topoisomerase II-mediated DNA breaks in RPMI 8402 cells by alkaline sedimentation analysis. When RPMI 8402 cells were exposed to VP-16 in the presence of ICRF-154 or ICRF-193 for 1 h, VP-16-induced DNA strand breaks were greatly inhibited by both ICRF compounds. In parallel with this observation, VP-16-induced growth inhibition was also reversed by ICRF-193. Exposure of cells to ICRF-154 resulted in a progressive accumulation of cells with 4C DNA content. Although mitotic index did not significantly increase, mitotic abnormalities were seen in cells exposed to ICRF-193 or ICRF-154: all mitotic cells exhibited early mitotic figures with fewer condensed and entangled chromosomes. The most sensitive phase of the cell cycle to ICRF-154 was the G2-M. ICRF-154 did not affect the spindle formation. However, abnormally oriented spindles were observed in drug-treated cells in parallel with the appearance of multinucleated cells. The results suggest that ICRF-154 and -193 inhibit topoisomerase II activity in RPMI 8402 cells, and this effect resulted in the appearance of cells in G2 and early M phase with fewer condensed and entangled chromosomes and of cells with multilobed nuclei.
authors.affiliation: Laboratory of Biochemistry, Aichi Cancer Center Research Institute, Nagoya, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Ishida
authors.forename: T
authors.initials: T
authors.lastname: Miki
authors.forename: T
authors.initials: T
authors.lastname: Narita
authors.forename: R
authors.initials: R
authors.lastname: Yui
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: K R
authors.initials: KR
authors.lastname: Utsumi
authors.forename: K
authors.initials: K
authors.lastname: Tanabe
authors.forename: T
authors.initials: T
authors.lastname: Andoh
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D004249:DNA Damage; D054659:Diketopiperazines; D006801:Humans; D008938:Mitosis / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D011929:Razoxane / Q000031:analogs & derivatives* / Q000494:pharmacology; D008941:Spindle Apparatus / Q000187:drug effects; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
chemical_list: D054659:Diketopiperazines; D010879:Piperazines; D059005:Topoisomerase II Inhibitors; C070899:4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione; D011929:Razoxane; C000283:1,2-bis(3,5-dioxopiperazin-1-yl)ethane