Ailanthone induces autophagic and apoptotic cell death in human promyelocytic leukemia HL-60 cells

Ailanthone, which is extracted from the traditional Chinese medicinal plant Ailanthus altissima, has been thoroughly demonstrated to have anti-tumor, anti-HIV, anti-inflammatory, anti-malarial, anti-allergic and anti-microbial activities. However, the anti-proliferative effects of ailanthone on HL-60 cells and potential mechanisms underlying those effects have not been reported. In the present study, we demonstrated the potent cytotoxicity of ailanthone against HL-60 cells. Annexin V-APC/7-ADD staining assay indicated that ailanthone increased the number of apoptotic cells in a dose-dependent manner. PI staining showed that ailanthone increased the percentage of G0/G1-phase cells in a dose-dependent manner. Acridine orange staining suggested that ailanthone induced the formation of acidic vesicular organelles in HL-60 cells and pretreatment with BaF-A1 could attenuate this process. Western blotting showed that ailanthone up-regulated the protein expression levels of beclin-1 and LC3-II and down-regulated those of LC3-I and p62 in a dose-dependent manner. Use of BaF-A1 showed that the anti-proliferative effects of ailanthone on HL-60 cells may be partly attributable to the induction of autophagy-mediated apoptosis by MTT assay and annexin V-APC/7-ADD staining assay.