Cell-Type-Specific Effects of Silibinin on Vitamin D-Induced Differentiation of Acute Myeloid Leukemia Cells Are Associated with Differential Modulation of RXRα Levels
Figure 5
Silibinin promotes downregulation of RXRα in U937 cells but not in HL60 cells. (a), (b) HL60 and U937 cells (5 × 104 cells/mL) were treated with 0.1% ethanol (control) or the indicated test agents, for 24 h. RXRα mRNA expression was determined by quantitative RT-PCR. The data are the means ± SE of 3 independent experiments performed in duplicate. ♦, combination versus control.(c) U937 cells (5 × 104 cells/mL) were preincubated for 72 h with 0.1% ethanol (lanes 1–6), silibinin alone (lanes 7–9), or in combination with 1,25D (lanes 10–12) followed by treatment with vehicle (H2O, lanes 1–3) or cycloheximide (CHX, lanes 4–12) for 0–8 h, as indicated. Cells were then lysed and protein levels were determined by Western blotting. Calreticulin (CRN) was used as the protein loading control. Representative blots of 3 independent experiments are shown. (d) Graphical representation of changes in RXRα protein levels (determined as shown in panel (c)) relative to 0 h (lanes 1, 4, 7, 10, resp., for corresponding treatments); means ± SE; . ♦.
