Sanguinarine, a benzophenanthridine alkaloid, induces apoptosis in MDA-MB-231 human breast carcinoma cells through a reactive oxygen species-mediated mitochondrial pathway

Background: Sanguinarine is a benzophenanthridine alkaloid that is known to have antimicrobial, anti-inflammatory, antioxidant and anticancer properties. In this study, we examined the effects of this compound on reactive oxygen species (ROS) production and the association of these effects with apoptotic tumor cell death using a human breast carcinoma MDA-MB-231 cell line. Methods: Cytotoxicity was evaluated by trypan blue exclusion methods. Apoptosis was detected using DAPI staining, agarose gel electrophoresis and flow cytometer. The expression levels of proteins were determined by Western blot analyses and caspase activities were measured using colorimetric assays. The ROS production and mitochondrial membrane potential (MMP, Delta Psi(m)) changes were measured fluorimetrically. Results: The results of this study demonstrate that sanguinarine mediates ROS production, and that this mediation is followed by a decrease in MMP, the release of cytochrome c, activation of caspase-9 and caspase-3, and downregulation of antiapoptosis factor XIAP and cIAP-1. Sanguinarine also promoted the activation of caspase-8 and truncation of Bid (tBid). Moreover, the quenching of ROS generation by N-acetyl-L-cysteine administration, a scavenger of ROS, reversed the sanguinarine-induced apoptosis effects via inhibition of ROS production, MMP collapse, tBid expression and the subsequent activation of caspases. These observations clearly indicate that ROS are involved in the early molecular events in the sanguinarine-induced apoptotic pathway. Conclusion: Our data imply that sanguinarine-induced ROS are key mediators of MMP collapse, which leads to the release of cytochrome c followed by caspase activation, culminating in apoptosis. Copyright (C) 2008 S. Karger AG, Basel.