RESUMEN
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.
RESUMEN
Objective To investigate the effect of simvastatin (SV) in combination with cytosine arabinoside (ARA-C) on the proliferation and apoptosis of K562 cells. Methods Human K562 cells were incubated with SV and cytosine arabinoside alone or in combination and K562 cells without any treatment were taken as normal control. Cells in different groups were collected at 24, 48 and 72 h after incubation for further detections. Morphological changes by Wright stain were performed. MTT method was used to assay the growth inhibition rate and cytoflowmetry was used to detect the early stage apoptosis ratio and cell necrosis ratio. Results Compared with Ara-C group and SV group, cells in the group treated with SV combined with Ara-C showed obvious karyopyknosis,apoptosis bodies formation and significant cell growth inhibition, which were positively correlated with culture time. Combination of 15 μmol/L SV and Ara-C showed the most significant cell growth inhibition with a inhibition rate of (72±1) % at 72 h of culture, as was significantly higher than that of 15 μmol/L SV group (45±2) % and 20 μmol/L Ara-C group (44±0) % (P ＜0.01),furthermore, combination of 15 μmol/L simvastatin and Ara-C showed synergistic inhibition with Q value of 1.24 and 1.19 at 24 h and 48 h in each. The apoptosis rates at early stage (AnnexinV) detected by flow cytometry in 20 μmol/L, 15 μmol/L and 10 μmol/L SV treated K562 cells were significantly higher than that in normal K562 cells (P ＜0.01), as were positively correlated with culture time and SV dose (P ＜0.05). There were no significant difference of early apoptosis rate between the 20 μmol/L SV and 15 μmol/L SV groups (P ＞0.05), yet the very two were both higher than that of 10 μmol/L SV group (P ＜0.05). There were no statistic differences of late apoptosis rate (PI) amongdifferent treated groups (P ＞0.05). Conclusion SV inhibited K562 cell proliferation and induced cell apoptosis in vitro, and combination of SV and Ara-C exhibited obvious synergistic inhibition and apoptosis, which may increase the sensitivity of K562 cell to chemotherapy. SV at 15 μmol/L may be the best concentration for K562 cells in vitro.
