Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 276, Issue 48, Pages 44488-44494Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M104383200
Keywords
-
Categories
Funding
- NCI NIH HHS [CA74939, R01 CA80961, N01-CM-57201, U01CA63185, CA16058] Funding Source: Medline
- NIDDK NIH HHS [DK56917] Funding Source: Medline
Ask authors/readers for more resources
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 II beta to DNA and stimulated topoisomerase II beta -mediated DNA cleavage at specific sites on P-32-end-labeled DNA. Human topoisomerase Ha-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 II beta -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
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available