Different topoisomerase II antitumor drugs direct similar specific long-range fragmentation of an amplified c-MYC gene locus in living cells and in high-salt-extracted nuclei.
We have analyzed the long-range distribution of topoisomerase II-mediated cleavages induced in an amplified human c-MYC gene locus in the presence of several antitumor agents. The long-range cleavage patterns were found to be nonrandom and similar for all antitumor drugs tested. Cleavages occurred within several kilobase-long areas (approximately 5 kb) highly accessible to topoisomerase II and separated by extended regions (approximately 70-100 kb) of less accessibility, possibly reflecting the mode of DNA organization into loops along the chromosome. Within the cleavage areas, the patterns of cleavage sites showed a certain dependence on the type of drug used for entrapment of topoisomerase II-DNA complexes. Importantly, distribution of cleavage areas in native chromatin and histone-depleted nuclei was very similar, if not identical, suggesting that the primary target of antitumor agents in vivo is topoisomerase II associated with the high-salt-insoluble nuclear matrix. These data show that matrix-attached DNA is preferentially damaged by topoisomerase II-targeting agents, which may be an important cellular event contributing to drug-induced cell death.
Gromova
I I
II
Department of Molecular Biology, University of Aarhus, Denmark.
Thomsen
B
B
Razin
S V
SV
D000677:Amsacrine / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018288:Carcinoma, Small Cell; D002458:Cell Fractionation / Q000379:methods; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000378:metabolism; D005047:Etoposide / Q000494:pharmacology; D005091:Exons; D016259:Genes, myc; D006801:Humans; D008175:Lung Neoplasms; D015183:Restriction Mapping; D012462:Saline Solution, Hypertonic; D013713:Teniposide / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D012462:Saline Solution, Hypertonic; D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D005047:Etoposide; D013713:Teniposide; D004250:DNA Topoisomerases, Type II