Apoptosis triggered by vitexin in U937 human leukemia cells via a mitochondrial signaling pathway.

Vitexin, a lignan compound, has been shown to exert apoptotic actions on human breast cancer cell lines and to have anti-inflammatory activities. Nevertheless, there is currently no study addressing the effects of vitexin on the induction of apoptosis in U937 human leukemia cells. The aim of this study was to determine the anticancer effects and molecular mechanisms of vitexin on U937 leukemia cells. We showed that vitexin can potently induce programmed cell death in U937 leukemia cell growth as well as morphological changes that were examined by MTT assay and phase contrast microscopy, respectively. The DNA content and the levels of mitochondrial membrane potential (∆Ψm) were determined by flow cytometric analysis. The cell cycle arrest-regulated and apoptosis-associated protein levels were measured by western blotting. Vitexin-triggered apoptosis was accompanied by a decrease of the level of ∆Ψm and the percentage of viability and provoked apoptosis in U937 cells. The downregulation of the protein level for Bcl-2 with the simultaneous upregulation of caspase-3 and -9 protein expression in U937 cells were observed after treatment with vitexin. Therefore, our data provide a potential mechanism for the chemopreventive activity of vitexin, and we suggest that vitexin may serve as a therapeutic agent for the treatment of human leukemia.