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Nuclear topoisomerase II levels correlate with the sensitivity of mammalian cells to intercalating agents and epipodophyllotoxins

Lookup NU author(s): Professor Craig Robson, Dr Sally Davies


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We have investigated the biochemical basis for the hypersensitivity to intercalating agents and epipodophyllotoxins of a Chinese hamster cell mutant, ADR-1. More topoisomerase II-induced DNA strand breaks are accumulated by ADR-1 than by parental CHO-K1 cells following exposure to the intercalating agent amsacrine. Levels of induced DNA strand breaks correlate with cell killing. Topoisomerase II activity is elevated in ADR-1 cells as a consequence of an increased cellular level of topoisomerase II protein. We have studied the phenotype of cell hybrids generated by fusing parental and mutant cells. The hybrid ADR-1/CHO-K1 exhibits normal levels of resistance to amsacrine and expresses the lower, parental level of topoisomerase II. These results provide additional evidence that topoisomerase II mediates the cytotoxic action of intercalating agents and epipodophyllotoxins and suggest that the intracellular level of topoisomerase II is an important determinant of cellular sensitivity to these drugs. This has implications for antitumor therapy. ADR-1 cells provide a model system for studying the effects of topoisomerase II overproduction on cell proliferation and chromosome organization.

Publication metadata

Author(s): Davies SM, Robson CN, Davies SL, Hickson ID

Publication type: Article

Journal: Journal of Biological Chemistry

Year: 1988

Volume: 263

Issue: 33

Pages: 17724-17729

Print publication date: 25/11/1988

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X


Notes: 0021-9258 Journal Article


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