THE EFFECT OF ATRA ON THE APOPTOSIS IN HL 60 CELLS INDUCED BY Ara C

Objective:To investigate the effect of ATRA on the apoptosis in HL 60 cells induced by Ara C.Methods:By means of light microscopy,DNA electrophoresis and flow cytometric analysis to detect apoptotic cells,DNA ladders and the percentage of apoptotic cells and the cells in every stage,percentage expression and the mean fluorescence intensity(MFI) of bcl 2,respectively.Results:After the cells were incubated with ATRA 0.3 mg/L for 72 hours,the percentage of cells in S stage obviously reduced to 32.9% ( P 0.05),the percentage of cells in G 0/G 1 stage greatly increased up to 58.5% ( P 0.05),respectively.After the cells were treated with Ara C 1.5 mg/L for 4 hours,the percentage of apoptotic cells was 55.1%.After the cells were incubated with ATRA 0.3 mg/L for 72 hours and subsequently treated with Ara C 1.5mg/L for 4 hours,the percentage of apoptotic cells obviously reduced to 34.4%( P 0.05).DNA electrophoresis of ATRA in combination with Ara C treated cells showed less bright DNA ladder than Ara C treated cells.Conclusion:ATRA offers HL 60 cells resistance to apoptosis induced by Ara C,whose mechanism may be related to an increase in amount of cells in G 0/G 1 stage after the cells incubated with ATRA.