Topoisomerase II poisoning by ICRF-193.

Abstract

Antineoplastic bis(dioxopiperazine)s, such as meso-2,3-bis(2,6-dioxopiperazin-4-yl)butane (ICRF-193), are widely believed to be only catalytic inhibitors of topoisomerase II. However, topoisomerase inhibitors have little or no antineoplastic activity unless they are topoisomerase poisons, a special subclass of topoisomerase-targeting drugs that stabilize topoisomerase-DNA strand passing intermediates and thus cause the topoisomerase to become a cytotoxic DNA-damaging agent. Here we report that ICRF-193 is a very significant topoisomerase II poison. Detection of topoisomerase II poisoning by ICRF-193 required the use of a chaotropic protein denaturant in the topoisomerase poisoning assays. ICRF-193 caused dose-dependent cross-linking of human topoisomerase IIbeta to DNA and stimulated topoisomerase IIbeta-mediated DNA cleavage at specific sites on (32)P-end-labeled DNA. Human topoisomerase IIalpha-mediated DNA cleavage was stimulated to a lesser extent by ICRF-193. In vivo experiments with MCF-7 cells also showed the requirement of a chaotropic protein denaturant in the assays and selectivity for the beta-isozyme of human topoisomerase II. Studies with two topoisomerase IIbeta-negative cell model systems confirmed significant topoisomerase II poisoning by ICRF-193 in the wild type cells and were consistent with beta-isozyme selectivity. Common use of only the detergent, SDS, in assays may have led to failure to detect topoisomerase II poisoning by ICRF-193 in earlier studies.

• Authors: K C Huang, H Gao, E F Yamasaki, D R Grabowski, S Liu, L L Shen, K K Chan, R Ganapathi, R M Snapka
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 276 Issue 48 Pg. 44488-94 (Nov 30 2001) ISSN: 0021-9258 [Print] United States
• PMID: 11577077 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Diketopiperazines
• Enzyme Inhibitors
• Piperazines
• Topoisomerase II Inhibitors
• 4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione
• DNA Topoisomerases, Type II

Topics

• Base Sequence
• Blotting, Western
• Catalysis
• Cell Nucleus (enzymology)
• DNA Topoisomerases, Type II (metabolism)
• Diketopiperazines
• Dose-Response Relationship, Drug
• Enzyme Inhibitors (pharmacology)
• Humans
• Molecular Sequence Data
• Piperazines (pharmacology)
• Substrate Specificity
• Time Factors
• Topoisomerase II Inhibitors
• Tumor Cells, Cultured