Apicularen A is a novel antitumor agent and strongly induces death in tumor cells. In this study, we synthesized apicularen A acetate, an acetyl derivative of apicularen A, and investigated its antitumor effect and mechanism in HM7 colon cancer cells. Apicularen A acetate induced apoptotic cell death and caspase-3 activation; however, the pan-caspase inhibitor Z-VAD-fmk could not prevent this cell death. Apicularen A acetate induced the loss of mitochondrial membrane potential and the translocation of apoptosis-inducing factor (AIF) from mitochondria. In addition, apicularen A acetate significantly decreased tubulin mRNA and protein levels and induced disruption of microtubule networks. Taken together, these results indicate that the mechanism of apicularen A acetate involves caspase-independent apoptotic cell death and disruption of microtubule architecture. (C) 2013 Elsevier Inc. All rights reserved.