Lapcin is a potent dual topoisomerase I/II inhibitor with nM to pM IC50s against diverse cancer cell lines (Colon cancer HT29 cell IC50=0.516 nM);
Lapcin showed weak activity against DNA gyrase (IC50>20.5 uM).
While only weakly active against DNA gyrase, lapcin was a potent of inhibitor of both DNA relaxation by topoisomerase I (IC50=2.17 uM) and DNA decatenation by topoisomerase II (IC50=7.53uM), 14 times more potent than the alkaloid camptothecin.
Lapcin was more potent than the topoisomerase II inhibitor etoposide against all of the cell lines we tested, with the exception of the lung cancer cell NCI-H226, against which it was essentially equipotent.
Cell lines expressing wild-type p53 (HCT116, H226, MCF7) tended to show higher IC50s than p53 reduced cell lines (NCI-H1299, HT29, Colo205, Hela).
