Abstract:

To investigate the induction  of fluvastatin (Flu) on apoptosis of human promyelocytic leukemia cells (HL-60 cells) and its mechanism,and  provide theoretical basis for clinical application of Flu. Methods The cultured HL-60 cells in vitro were divided into blank control,positive control group (ATRA,10  μmol·L^-1),Flu (20  μmol·L^-1) group and Flu (20  μmol·L^-1)+ mevalonate (Mev,100  μmol·L^-1) group. After HL-60 cells were treated,the caspase-3 activity was determined using CaspACETM Assay System for exploring the  apoptosis,the apoptosis was analyzed by flow cytometry after annexin V-FITC/PI double staining,the laddered pattern of DNA fragments was evaluated by DNA agarose gel electrophoresis and the ultrastructural changes of HL-60 cells were observed by transmission electron microscope. Results After Flu treatment for 24 h,the caspase-3 activity in HL-60 cells was significantly higher (A405,30.68 ±1.57) than that in control cells (12.05±2.15,P<0.01). In HL-60 cells co-treated with Flu and Mev,the caspase-3 activity was markedly reduced (14.62 ±1.36),nearing to the level in control cells (P>0.05). Flow cytometry showed that compared with control,the apoptotic rate in Flu-treated HL-60 cells was significantly increased (4.24%  vs  10.76%,P<0.01),and the apoptotic rate was decreased to 5.11% after HL-60 cells were co-treated with Flu and Mev (P>0.05). DNA agarose gel electrophoresis revealed a laddered pattern of DNA fragments in Flu-treated HL-60 cells after 72 h treatment. In Flu-treated HL-60 cells,electron microscopic study exhibited the diminished cell body,condensed cytoplasm and nuclear chromatin condensation aggregating under the nuclear membrane,and the intact cell membrane and organelle. Conclusion Flu can induce the apoptosis of HL-60 cells and this effect is dependent on mevalonate(Mev) pathway,suggesting that the inhibition
of Mev pathway may be one of molecular mechanisms for Flu-induced apoptosis of  HL-60 cells.

Key words: fluvastatin;HL-60 cell;apoptosis;mevalonate pathway