Effects of simvastatin on differentiation and apoptosis of human promyelocytic leukemia cell line NB4 / 白血病·淋巴瘤

ABSTRACT

Objective To investigate the effects of simvastatin (SV) on the proliferation,differentiation and apoptosis of human promyelocytic leukemia cell line NB4.Methods NB4 cells were incubated with SV at different concentration with or without all-trans retinoic acid (ATRA),and NB4 cells without any treatment were taken as normal control.Cells of different groups were collected at 24 h,48 h and 72 h after incubation for further detection.Morphological changes by Wright stain were performed.MTT method was used to assay the growth inhibition rate and flow cytometry was used to detect the surface CD11b expression levels,the early stage apoptosis ratio and cell necrosis ratio.Results Treated with 15 μ mol/L SV,10 μ mol/L SV and 5 μ mol/L SV respectively,with the NB4 cells growth,the cell inhibition rates gradually increased (F =7.15,P =0.000),as well as CD11b expression levels (F =3.41,P =0.014) and AnnexinVexpression levels (F =43.38,P =0.000).Furthermore the NB4 cells treated with 15 μ mol/L SV exhibited the most significant changes with cell inhibition rate of 0.96±0.02,CD11b expression level increased to (62.41±6.37) ％ and AnnexinV expression level increased to (87.38±2.94) ％ after 72 h incubation.Combination of 15 μmol/L SV with 0.5 μmol/L ATRA displayed obvious interaction for increasing CD11b expression levels (F =4.093,P =0.025),while no significant interaction for cell inhibition rates and Annexin V expression levels were observed.After 72 h incubation,the CD11b expression levels (89.46±9.13) ％ in NB4 cells treated with 15 μ mol/L SV in combination with 0.5 μ mol/L ATRA were significantly higher than those treated with ATRA (71.27±7.27) ％ and SV (62.41±6.37) ％ (t =2.71,P =0.054; t =4.37,P =0.017)' solely.Conclusion Simvastatin in vitro inhibits NB4 cell proliferation,promotes cell apoptosis,and synergistically induces cell differentiation with ATRA dose-dependently in vitro,which indicates that SV may have the effect of synergistic anti-promyelocytic potency with ATRA.