Development of a novel class of tubulin inhibitors with promising anticancer activities.

UNLABELLED We have developed a novel class (2-amino-4-phenyl-4H-chromene-3-carboxylate) of inhibitors of tubulin assembly by modifying HA14-1, which is a Bcl-2 inhibitor discovered by our group. Three of these compounds, mHA1, mHA6, and mHA11, showed in vitro cytotoxicities against tumor cells that were more potent and more stable than the backbone compound HA14-1, with nM IC50 values. In contrast, the cytotoxic effects of these compounds on normal cells were minimal. Computational docking, colchicine-tubulin competitive binding, and tubulin polymerization studies demonstrated that these compounds bind at the colchicine-binding site on tubulin and inhibit the formation of microtubules. Treatment of HL-60/Bcl-2 leukemia and CRL5908 lung cancer cells with these mHA compounds led to pronounced microtubule density decreases, G2/M cell cycle arrest, and apoptosis, as determined by immunofluorescence microscopy, flow cytometry, and DNA fragmentation analysis. Combined, these data identify a novel class of compounds that inhibit tubulin assembly and limit cancer cell phenotypes. IMPLICATIONS This study supports the continued development of novel anti-tubulin assembly inhibitors as potential anticancer agents.