Mediation of multi-drug resistance in a Chinese hamster ovary cell line by a mutant type II topoisomerase

Identification of DNA topoisomerase II as the intracellular target for the DNA cleavage activity of the epipodophyllotoxins and several intercalating agents is well established. In contrast, definite correlation of cleavable complex formation with eventual cell death has been more difficult to document. Our studies with an epipodophyllotoxin resistant cell line not only provide additional evidence that the enzyme is a multi-drug target, but …