PT  - JOURNAL ARTICLE
AU  - M. Sorensen
AU  - M. Sehested
AU  - P. B. Jensen
TI  - Effect of Cellular ATP Depletion on Topoisomerase II Poisons. Abrogation of Cleavable-Complex Formation by Etoposide But Not by Amsacrine
DP  - 1999 Mar 01
TA  - Molecular Pharmacology
PG  - 424--431
VI  - 55
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/55/3/424.short
4100  - http://molpharm.aspetjournals.org/content/55/3/424.full
SO  - Mol Pharmacol1999 Mar 01; 55
AB  - Topoisomerase (topo) II poisons have been categorized into ATP-independent and -dependent drugs based on in vitro studies. We investigated drug-induced topoII-DNA complexes in intact cells almost completely depleted of ATP. Virtually no DNA single-strand breaks (SSBs), as measured by alkaline elution, were detected in energy-depleted cells treated with the topoII poisons etoposide, teniposide, daunorubicin, doxorubicin, mitoxantrone, or clerocidin. This inhibition was reversible; subsequent incubation with glucose restored the level of DNA SSBs. The effect of ATP depletion was specific for topoII, because topoI-mediated cleavable complexes induced by camptothecin were unaffected by ATP depletion. Furthermore, etoposide-induced DNA-protein complexes and DNA double-strand breaks, as measured by filter elution techniques, and topoIIα and -β trapping, as measured by a band depletion assay, were completely inhibited by energy depletion. Differences in drug transport could not explain the effect of ATP depletion. The topoII poison amsacrine (m-AMSA) was unique with respect to ATP dependence. In ATP-depleted cells, m-AMSA-induced DNA SSBs, DNA double-strand breaks, DNA-protein complexes, topoIIα and -β trapping were only modestly reduced. The accumulation ofm-AMSA was reduced in ATP-depleted cells, which indicates that drug transport could contribute to the modest decrease in m-AMSA-induced cleavable complexes. In conclusion, drug-induced topoII-DNA complexes were completely antagonized in ATP-depleted cells, except in the case of m-AMSA. One possible interpretation is that m-AMSA mainly produces prestrand passage DNA lesions, whereas the other topoII poisons tested exclusively stabilize poststrand passage DNA lesions in intact cells. The American Society for Pharmacology and Experimental Therapeutics