Atp-bound topoisomerase ii as a target for antitumor drugs.
Topoisomerase II (TOP2) poisons interfere with the breakage/reunion reaction of TOP2 resulting in DNA cleavage. In the current studies, we show that two different classes (ATP-sensitive and -insensitive) of TOP2 poisons can be identified based on their differential sensitivity to the ATP-bound conformation of TOP2. First, in the presence of 1 mm ATP or the nonhydrolyzable analog adenosine 5'-(beta,gamma-imino)triphosphate, TOP2-mediated DNA cleavage induced by ATP-sensitive TOP2 poisons (e.g. doxorubicin, etoposide, mitoxantrone, and 4'-(9-acridinylamino)methanesulfon-m-anisidide) was 30-100-fold stimulated, whereas DNA cleavage induced by ATP-insensitive TOP2 poisons (e.g. amonafide, batracylin, and menadione) was only slightly (less than 3-fold) affected. In addition, ADP was shown to strongly antagonize TOP2-mediated DNA cleavage induced by ATP-sensitive but not ATP-insensitive TOP2 poisons. Second, C427A mutant human TOP2alpha, which exhibits reduced ATPase activity, was shown to exhibit cross-resistance to all ATP-sensitive but not ATP-insensitive TOP2 poisons. Third, using ciprofloxacin competition assay, TOP2-mediated DNA cleavage induced by ATP-sensitive but not ATP-insensitive poisons was shown to be antagonized by ciprofloxacin. These results suggest that ATP-bound TOP2 may be the specific target of ATP-sensitive TOP2 poisons. Using Lac repressor-operator complexes as roadblocks, we show that ATP-bound TOP2 acts as a circular clamp capable of entering DNA ends and sliding on unobstructed duplex DNA.
Wang
H
H
Department of Pharmacology, University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Mao
Y
Y
Zhou
N
N
Hu
T
T
Hsieh
T S
TS
Liu
L F
LF
D000255:Adenosine Triphosphate / Q000378:metabolism*; D019943:Amino Acid Substitution; D000677:Amsacrine / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002417:Cattle; D004250:DNA Topoisomerases, Type II / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D007700:Kinetics; D008942:Mitoxantrone / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D013713:Teniposide / Q000494:pharmacology; D013950:Thymus Gland / Q000201:enzymology
D000970:Antineoplastic Agents; D011994:Recombinant Proteins; D000677:Amsacrine; D005047:Etoposide; D004317:Doxorubicin; D000255:Adenosine Triphosphate; D013713:Teniposide; D008942:Mitoxantrone; D004250:DNA Topoisomerases, Type II