title: Anthracycline-dependent heat-induced transition from positive to negative supercoiled DNA.
abstract: The conformational stability of individual DNA topoisomers depends on the concentration of DNA intercalating drugs. To study the DNA-drug interaction, we used ethidium bromide (EtBr) and negative supercoiled pUC19 as a model system. The effects of two anthracyclines widely used in cancer therapy, daunorubicin (Dau) and doxorubicin (Doxo), and EtBr were compared. In spite of their different chemical structures and intercalation mode, all intercalating agents show similar effects on the conformational stability of supercoiled DNA. Our observations show that the studied intercalators have at least two main effects on the supercoiled DNA: (i) they decrease the level of negative supercoiling and, at certain concentrations, they may induce positive supercoiling in DNA; (ii) a temperature increase can cause a recovery of negative supercoiling in DNA. The conformational stability of plasmid DNA-drug complexes has been investigated by temperature gradient gel electrophoresis (TGGE). We demonstrate the suitability of TGGE for this purpose, because it offers a global view on DNA-drug complexes over a continuous range of temperature. Images of DNA plasmids adsorbed onto a substrate at different temperatures and drug concentrations were acquired by atomic force microscopy (AFM), allowing us to distinguish directly the conformation chirality assumed by the plasmid under different conditions confirming TGGE results. Our detection system allows to characterize unknown drugs and to determine their intercalating properties.
authors.affiliation: Institute of Chemistry, Department of Biochemistry, Faculty of Sciences, P. J. Safarik University, Kosice, Slovakia. viglasky@kosice.upjs.sk
authors.forename: Viktor
authors.initials: V
authors.lastname: Víglasky
authors.forename: Francesco
authors.initials: F
authors.lastname: Valle
authors.forename: Jozef
authors.initials: J
authors.lastname: Adamcík
authors.forename: Irene
authors.initials: I
authors.lastname: Joab
authors.forename: Dusan
authors.initials: D
authors.lastname: Podhradsky
authors.forename: Giovanni
authors.initials: G
authors.lastname: Dietler
mesh_terms: D018943:Anthracyclines / Q000494:pharmacology*; D001435:Bacteriophages / Q000235:genetics; D004278:DNA, Superhelical / Q000737:chemistry* / Q000187:drug effects / Q000528:radiation effects; D003630:Daunorubicin / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004587:Electrophoresis, Agar Gel / Q000379:methods; D004996:Ethidium / Q000494:pharmacology; D006358:Hot Temperature; D007364:Intercalating Agents / Q000494:pharmacology; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation / Q000187:drug effects / Q000528:radiation effects; D044367:Phase Transition / Q000187:drug effects / Q000528:radiation effects
chemical_list: D018943:Anthracyclines; D004278:DNA, Superhelical; D007364:Intercalating Agents; D004317:Doxorubicin; D004996:Ethidium; D003630:Daunorubicin