Beta-asarone Induces LoVo Colon Cancer Cell Apoptosis by Up-regulation of Caspases through a Mitochondrial Pathway in vitro and in vivo

Abstract

Beta-asarone is one of the main bioactive constituents in traditional Chinese medicine Acorus calamu. Previousstudies have shown that it has antifungal and anthelmintic activities. However, little is known about its anticancereffects. This study aimed to determine inhibitory effects on LoVo colon cancer cell proliferation and to clarifythe underlying mechanisms in vitro and in vivo. Dose-response and time-course anti-proliferation effects wereexamined by MTT assay. Our results demonstrated that LoVo cell viability showed dose- and time-dependence onβ-asarone. We further assessed anti-proliferation effects as β-asarone-induced apoptosis by annexin V-fluoresceinisothiocyanate/propidium iodide assay usinga flow cytometer and observed characteristic nuclear fragmentationand chromatin condensation of apoptosis by microscopy. Moreover, we found the apoptosis to be induced throughthe mitochondrial/caspase pathway by decreasing mitochondrial membrane potential (MMP) and reducing theBcl-2-to-Bax ratio, in addition to activating the caspase-9 and caspase-3 cascades. Additionally, the apoptosiscould be inhibited by a pan-caspase inhibitor, carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone(Z-VAD-FMK). When nude mice bearing LoVo tumor xenografts were treated with β-asarone, tumor volumeswere reduced and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assays ofexcised tissue also demonstrated apoptotic changes. Taken together, these findings for the first time provideevidence that β-asarone can suppress the growth of colon cancer and the induced apoptosis is possibly mediatedthrough mitochondria/caspase pathways.