[Effects of plumbagin on the human acute promyelocytic leukemia cells in vitro]

According to previous clinical experiences of the authors, plumbago zeylanica was effective against acute promyelocytic leukemia (APL). However, its effectiveness has never been proven experimentally or unequivocally clinically. This study was aimed to investigate the effects of plumbagin on the proliferation, cell cycle and apoptosis of APL cell line NB4 Cells. Cell inhibitory rates were detected by MTT colorimetric assay; morphologic changes were observed under light microscope and transmission electron microscope; apoptosis-inducing effects were determined by DNA gel electrophoresis, annexin V/PI double-stained and PI single-stained flow cytometry. The results demonstrated that 2-15 micromol/L plumbagin inhibited the proliferation of NB4 cells in a dose-dependent manner. The morphologic changes of cell apoptosis, such as chromsome condensation and apoptotic body formation, were observed by light microscope and transmission electron microscope. Cell cycle analysis showed that NB4 cells were blocked in G2/M phase of cell cycle. And plumbagin induced annexin V+/PI- cell increase and DNA fragmentation. There was a correlation between cell apoptosis rates and the concentrations of plumbagin in dose-dependent manner (P < 0.05). It is concluded that for the first time the present study shows that plumbagin can inhibit cell proliferation, block cell cycle and induce apoptosis of APL cell line NB4 cells.