Stability of adriamycin-induced DNA adducts and interstrand crosslinks.
The stability of adriamycin-induced DNA adducts and interstrand crosslinks was measured at 37 degrees C by three independent procedures. The loss of [14C]-labelled adducts was described by two first-order decays with half-lives of 7.4 h (60% amplitude) and 39 h (40%). The loss of the drug chromophore also exhibited a biphasic character, with half-lives of 6 h (65%) and approximately 150 h (35%). The decay of transcriptional blockages at an isolated, apparent interstrand GpC crosslinking site was described by two first-order processes, with half-lives of 3 h (65%) and 40 h (35%), whereas the decay of transcriptional blockages at an isolated guanine residue (apparent site of monoadduct) was completely described by a first-order decay with a half-life of 5.3 h. The loss of interstrand crosslinks was measured using a gel electrophoresis assay, and the decay was characterised by a single first-order process with a half-life of 4.7 h. Collectively, these values serve to define a model of the interstrand crosslink with unstable sites of attachment at both ends of the crosslink, with half-lives at either end being approximately 5 and 40 h. The adducts exhibited increasing lability with increasing pH, and were particularly unstable at pH 12, with a half-life of approximately 0.5 h. The adducts were also heat labile, with an overall melting temperature of 67 degrees C (10 min exposure) and this was also the thermal lability measured at three individual adduct sites probed by lambda exonuclease.
van Rosmalen
A
A
School of Biochemistry, La Trobe University, Bundoora, Victoria, Australia.
Cullinane
C
C
Cutts
S M
SM
Phillips
D R
DR
D000818:Animals; D002417:Cattle; D003432:Cross-Linking Reagents; D018736:DNA Adducts / Q000737:chemistry* / Q000187:drug effects* / Q000235:genetics; D004317:Doxorubicin / Q000737:chemistry / Q000494:pharmacology*; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006207:Half-Life; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008956:Models, Chemical; D009691:Nucleic Acid Denaturation; D014158:Transcription, Genetic
D003432:Cross-Linking Reagents; D018736:DNA Adducts; C031902:doxorubicin-DNA; D004317:Doxorubicin