Interaction of bisantrene anti-cancer agents with DNA: footprinting, structural requirements for DNA unwinding, kinetics and mechanism of binding and correlation of structural and kinetic parameters with anti-cancer activity.
A topoisomerase I assay in conjunction with covalently closed circular DNA afforded unwinding angles for a series of eight analogs of the anti-cancer agent bisantrene. Values ranging from 33 degrees to zero comprised three classes wherein the extent of DNA interaction correlates with anti-cancer activity. The binding of bisantrene compounds to T4 DNA suggests at least partial interaction via the minor groove. MPE footprinting evaluation of bisantrene showed no evidence for selective protection of a Hind III-EcoRI fragment of pBR322 suggesting a sequence neutral binding mode. Stopped flow spectrophotometry studies indicate an association rate constant for bisantrene with DNA of greater than 1 x 10(7) M-1 S-1 at 20 degrees at ionic strength of 0.1 and is considerably slower than ethidium or propidium at all ionic strengths. At least two exponential components are required to match the kinetic curves indicating a biphasic mechanism and estimates of k1 and k2 were obtained for seven drugs. The ionic strength dependence of the surfactant driven dissociation of bisantrene is in accord with a competitive mechanism for intercalation of the drugs at alternative sites. The residence time and t1/2 (app) for bisantrene are slightly larger for poly d(G.C)2 than poly d(A.T)2 and calf thymus DNA is at an intermediate value. Considerations of structural factors in the drug dissociation kinetics permit a correlation with observed anti-cancer properties of these bisantrene analogs.
Elliott
J A
JA
Department of Chemistry, Georgia State University, Atlanta 30303.
Wilson
W D
WD
Shea
R G
RG
Hartley
J A
JA
Reszka
K
K
Lown
J W
JW
D000818:Animals; D000873:Anthracenes / Q000493:pharmacokinetics / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D002417:Cattle; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I / Q000378:metabolism / Q000494:pharmacology; D004270:DNA, Circular / Q000187:drug effects / Q000378:metabolism; D007364:Intercalating Agents; D007700:Kinetics; D009691:Nucleic Acid Denaturation / Q000187:drug effects; D013329:Structure-Activity Relationship
D000873:Anthracenes; D000970:Antineoplastic Agents; D004270:DNA, Circular; D007364:Intercalating Agents; C031404:bisantrene; D004247:DNA; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I