(A) Effect of As2O3and/or RA on NB4, NB4-R1, and NB4-R2 cell apoptosis. NB4, NB4-R1, and NB4-R2 were treated for 3 days with 10−6mol/L As2O3 or 10−6 mol/L RA, as indicated. Apoptosis was determined, after a TUNEL assay and PI-staining, by flow cytometry, and the % of apoptotic cells is reported in the plots. The abscissa of the plot represents TUNEL (apoptosis) and the ordinate represents PI (DNA quantity). (B) Western blot analysis of Bcl-2 in NB4 and NB4-R1 cells. Cells were grown for 48 hours in the presence of the indicated treatments. (C) Effect of As2O3 and/or RA on PML/RARα and RARα expression in NB4-R1 cells. The cells were treated for 2 days with either medium, 10−6 mol/L RA, 10−7mol/L As2O3, or the combination of 10−6 mol/L RA plus 10−7 mol/L As2O3. The two right lanes represent sequential treatments: 10−6 mol/L RA for 1 day followed by 10−7 mol/L As2O3 for the next day or 10−7 mol/L As2O3 for 1 day followed by 10−6 mol/L RA for the next day (far right lane).
