Molecular mechanism of apoptosis induced by schizandrae-derived lignans in human leukemia HL-60 cells

Schizandrae chinensis, a traditional Chinese medicine herb, has been used to treat hepatitis B disease in Chinese hospital clinic. We have isolated two bioactive compounds, deoxyschizandrin and γ-schizandrin, from S. chinensis. In the present, we reported that deoxyschizandrin and γ-schizandrin could induce apoptosis in human promyelocytic leukemia cells (HL-60), as characterized by DNA fragmentation and poly (ADP) ribose polymerase (PARP) cleavage. Further molecular analysis showed that deoxyschizandrin and γ-schizandrin caused the loss of mitochondrial membrane potential (ΔΨm), cytochrome c release from mitochondrion to cytosol, truncation of Bid protein, and activation of caspase-3 and -9. However, they did not increase the intracellular level of reactive oxygen species (ROS). Antioxidants such as N-acetyl cysteine (NAC) and catalase did not block the apoptosis induced by deoxyschizandrin or γ-schizandrin. These findings suggest that deoxyschizandrin and γ-schizandrin-induced apoptosis in HL-60 cells involved ROS-independent mitochondrial dysfunction pathway.