A novel use for the comet assay: detection of topoisomerase II inhibitors.
BACKGROUND
The simple and quick comet assay can quantitatively detect DNA cleavage in cells. This study aimed to determine whether the comet assay could be used to detect topoisomerase (topo) II inhibitors.


METHODS
HT-29 colon cancer cells were pre-incubated with aclarubicin, a topo II antagonist, then treated with topo II poisons: etoposide (VP-16), teniposide (VM-26), 4'-(acridinylamino) methansulfon-m-anisidide (m-AMSA) and adriamycin (doxorubicin). We also tested a topo I poison (camptothecin) and a microtubule depolymerization inhibitor (taxol).


RESULTS
Aclarubicin significantly reduced DNA cleavage induced by topo II poisons, but not that induced by camptothecin. In HL-60/MX2 cells (containing no topo II beta and reduced topo II alpha), DNA breakage induced by topo II poisons was lower. Also, aclarubicin antagonized topo I-mediated camptothecin-induced DNA cleavage in these resistant cells.


CONCLUSIONS
The comet assay can be used to detect topo II poisons in cultured cells. Also, aclarubicin has a dual topo I and topo II antagonism, with "preferential antagonism" of topo II when topo II beta catalytic activity is normally expressed.
Salti
G I
GI
University of Illinois at Chicago, College of Medicine, Department of Surgical Oncology (M/C 820) 60612, USA.
Das Gupta
T K
TK
Constantinou
A I
AI
D015250:Aclarubicin / Q000494:pharmacology; D000677:Amsacrine / Q000494:pharmacology; D002166:Camptothecin / Q000494:pharmacology; D020552:Comet Assay; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D004317:Doxorubicin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D018922:HL-60 Cells; D019073:HT29 Cells; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology*; D017239:Paclitaxel / Q000494:pharmacology; D013713:Teniposide / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors
D019384:Nucleic Acid Synthesis Inhibitors; D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D005047:Etoposide; D015250:Aclarubicin; D004317:Doxorubicin; D004247:DNA; D013713:Teniposide; D017239:Paclitaxel; D002166:Camptothecin