Apoptosis Effect Of K562 Cells Induced By Homoharringtonine Has A A Time Rhythm

Objective The aim of this study was to study the change of apoptosis rates of K562 cells at the different time after Homoharringtonine(HHT) treatment.Methods The proliferation activity of K562 cells at different time after Homoharringtonine(HHT) treatment was assayed by MTT. The apoptosis rate and expression of Bcl-2 gene were detected by flow cytometry and RT-PCR respectively. Western blot was chosen to analyze the expressin of apoptosis protein Caspase-3 Results 1. The viability of K562 cells reduced gradually from d1 to d5 and then ascended from d6 to d8 after HHT treatment. The apoptosis rate of K562 cells raised at the initial stage and then went down gradually during HHT treatment.2. The cleaved caspase-3 expression level of K562 cells increased gradually from d1 to d7, but began to fall at the 8th day (p<0.05).3. From dl to d7 during HHT treatment, the Bcl-2 expression level declined step by stept and start down at the 8th day (p<0.05).Conclusion The apoptosis level of K562 cells induced by HHT goes up at first and then declines.Objective The study was aimed to study the effect of HHT or HHT+3-MA on cell proliferation, apoptosis and autophagy of K562 cells.Methods Treated with lOng/ml HHT and 1.5mmol/L 3-MA, the expressions of caspase-3 and LC3â…¡/â… and Beclinl geneof K562 cells were analyzed with western blot and RT-PCR respectively.. Autophagosome were observed with electron microscope.Results 1. The expression level of Beclin-1 mRNA and LC3â…¡/â…  descended in the early stage (1-5d) and (1-6d) and increased in later time (6-8d) and (7-8d) respectively after being treated with HHT.2. The expression of caspase-3 protein showed a downward trend (8d) after the rise during dl-d7 after being treated with HHT.3. The expression level of Beclin-1 mRNA and LC3â…¡/â…  declined and caspase-3 protein ascended gradually during 1-8d in HHT unitingd 3-MA group. 4. Under electron microscopy,there were a lot of autophagosomes within K562 at the 8th d after HHT treatment but there were no autophagosomes in HHT+3-MA group.Conclusion HHT can induce autophagy of K562 cells, which may weaken the cytotoxicity of HHT on K562 cells, and the cytotoxicity of HHT can be enhanced when uniting with 3-MA.