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 3

Carnosic acid enhances while silibinin differentially affects 1,25D-induced VDRE transactivation in HL60 and U937 cells. Cells (5 × 10⁵ cells/ml) were transiently transfected with VDRE×6-luc and Renilla luciferase reporter constructs followed by treatment with 0.1% ethanol (control) or indicated test agents for 24 h. The relative VDREx6-luc activity (means ± SE) was calculated from the data of 3 individual experiments performed in triplicate. *𝑃<0.05 and **𝑃<0.01, combination versus sum of single agents for enhancing effects. ^♦𝑃<0.05, combination versus 1 nM 1,25D alone for inhibitory effects.

(a) HL60

(b) U937