title: Redox pathway leading to the alkylation of DNA by the anthracycline, antitumor drugs adriamycin and daunomycin.
abstract: Reaction of the anthracycline, antitumor drugs adriamycin and daunomycin with the self-complementary DNA oligonucleotide GCGCGCGC, (GC)4, in the presence of the reducing agent dithiothreitol, the oxidizing agent hydrogen peroxide, or the alkylating agent formaldehyde gives a similar mixture of DNA-drug adducts. Negative ion electrospray mass spectra indicate that adduct formation involves coupling of the DNA to the anthracycline via a methylene group and that the major adduct is duplex DNA containing two molecules of anthracycline, each bound to a separate strand of the DNA via a methylene group. The source of the methylene group is formaldehyde. A molecular structure with each anthracycline intercalated at a 5'-CpG-3' site and covalently bound from its 3'-amino group to a 2-amino group of a 2'-deoxyguanosine nucleotide is proposed based upon spectral data and a relevant crystal structure. The reaction of (GC)4 with the anthracyclines and formaldehyde forms an equilibrium mixture with DNA-drug adducts which is shifted toward free DNA by dilution. The results suggest a pathway to the inhibition of transcription by reductively activated adriamycin and daunomycin. Reductive activation in the presence of oxygen yields hydrogen peroxide; hydrogen peroxide oxidizes constituents in the reaction mixture to formaldehyde; and formaldehyde couples the drug to DNA. In this regard, hydrogen peroxide reacts with adriamycin via Baeyer-Villiger reactions at the 13-position to yield 2, 3, and formaldehyde. Formaldehyde also results from hydrogen peroxide oxidation of Tris [tris(hydroxymethyl)aminomethane] present in transcription buffer and spermine, a polyamine commonly associated with DNA in vivo, presumably via the Fenton reaction.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Taatjes
authors.forename: G
authors.initials: G
authors.lastname: Gaudiano
authors.forename: K
authors.initials: K
authors.lastname: Resing
authors.forename: T H
authors.initials: TH
authors.lastname: Koch
mesh_terms: D000478:Alkylation; D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism*; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism; D003630:Daunorubicin / Q000378:metabolism*; D004317:Doxorubicin / Q000378:metabolism*; D013058:Mass Spectrometry; D008956:Models, Chemical; D010084:Oxidation-Reduction
chemical_list: D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D018736:DNA Adducts; D004317:Doxorubicin; D004247:DNA; D003630:Daunorubicin