![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
Molecular Genetics Group, Department of Cellular and Molecular
Sciences, St. George's Hospital Medical School, University of London,
London SW17 0RE, UK.
Doxorubicin is a therapeutically useful anticancer drug that exerts
multiple biological effects. Its antitumor and cardiotoxic properties
have been ascribed to anthracycline-mediated free radical damage to DNA
and membranes. Evidence for this idea comes in part from the selection
by doxorubicin from stationary phase yeast cells of mutants (petites)
deficient in mitochondrial respiration and therefore defective in free
radical generation. However, doxorubicin also binds to DNA
topoisomerase II, converting the enzyme into a DNA damaging agent
through the trapping of a covalent enzyme-DNA complex termed the
`cleavable complex.' We have used yeast to determine whether
stabilization of cleavable complexes plays a role in doxorubicin action
and cytotoxicity. A plasmid-borne yeast TOP2 gene was
mutagenized with hydroxylamine and used to transform drug-permeable
yeast strain JN394t2-4, which carries a temperature-sensitive top2-4 mutation in its chromosomal TOP2
gene. Selection in growth medium at the nonpermissive temperature of
35° in the presence of doxorubicin resulted in the isolation of
plasmid-borne top2 mutants specifying functional
doxorubicin-resistant DNA topoisomerase II. Single-point changes of
Gly748 to Glu or Ala642 to Ser in yeast topoisomerase II, which lie in
and adjacent to the CAP-like DNA binding domain, respectively, were
identified as responsible for resistance to doxorubicin, implicating
these regions in drug action. None of the mutants selected in
JN394t2-4, which has a rad52 defect in double-strand DNA break repair,
was respiration-deficient. We conclude that topoisomerase II is an
intracellular target for doxorubicin and that the genetic background
and/or cell proliferation status can determine the relative importance
of topoisomerase II- versus free radical-killing.
This article has been cited by other articles:
|
|
 |
|
  N. Suda, Y. Ito, T. Imai, T. Kikumori, A. Kikuchi, Y. Nishiyama, S. Yoshida, and M. Suzuki The {alpha}4 residues of human DNA topoisomerase II{alpha} function in enzymatic activity and anticancer drug sensitivity Nucleic Acids Res., March 16, 2004; 32(5): 1767 - 1773. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Patel, E. Jazrawi, A. M. Creighton, C. A. Austin, and L. M. Fisher Probing the Interaction of the Cytotoxic Bisdioxopiperazine ICRF-193 with the Closed Enzyme Clamp of Human Topoisomerase IIalpha Mol. Pharmacol., September 1, 2000; 58(3): 560 - 568. [Abstract] [Full Text]
|
|
|
|
|
|
S. Patel, B. A. Keller, and L. M. Fisher Mutations at Arg486 and Glu571 in Human Topoisomerase IIalpha Confer Resistance to Amsacrine: Relevance for Antitumor Drug Resistance in Human Cells Mol. Pharmacol., April 1, 2000; 57(4): 784 - 791. [Abstract] [Full Text]
|
|
|
|
 |
|
 X.-S. Pan and L. M. Fisher DNA Gyrase and Topoisomerase IV Are Dual Targets of Clinafloxacin Action in Streptococcus pneumoniae Antimicrob. Agents Chemother., November 1, 1998; 42(11): 2810 - 2816. [Abstract] [Full Text]
|
|
|
|
 |
|
 M. Sabourin, J. A. W. Byl, S. E. Hannah, J. L. Nitiss, and N. Osheroff A Mutant Yeast Topoisomerase II (top2G437S) with Differential Sensitivity to Anticancer Drugs in the Presence and Absence of ATP J. Biol. Chem., October 30, 1998; 273(44): 29086 - 29092. [Abstract] [Full Text] [PDF]
|
|
 |
 |
 |
|
 |
 |
 |
