Effects of As2O3 or cAMP or both on PML-NB reorganization and PML-RARα degradation.
(A) Confocal microscopic analysis of PML-NBs in NB4 and NB4-R1 cells after a 72-hour exposure to the compounds indicated. Original magnification × 600. (B) Western blot analysis of PML-RARα during NB4 and NB4-R1 cell treatment with As2O3 in the presence and absence of 8-CPT-cAMP as indicated. (C) Transcriptional inhibition of PML-RARα protein on a DR5-RARE reporter with and without treatment of As2O3 or cAMP or both. COS-7 cells were cotransfected with 1 μg PML-RARα expression plasmid and 0.1 μg RARE-TK-luciferase reporter plasmid (see “Materials and methods”). The amount of plasmid was kept constant using empty vector. Twenty-four hours after transfection, COS-7 cells were treated with or without 10 nM ATRA, 0.25 μM As2O3, and 200 μM cAMP, as indicated. Luciferase activity was measured 48 hours after the transfection. The value indicated is a representative experiment among 3 independent assays. RLU indicates relative light units.
