Journal:

Article Title: Human Pregnane X Receptor Activation and CYP3A4/CYP2B6 Induction by 2,3-Oxidosqualene:Lanosterol Cyclase Inhibition

doi: 10.1124/dmd.108.025130

Figure Lengend Snippet: Concentration-dependent abilities of squalene 2,3-oxide and squalene 2,3:22,23-dioxide treatments to activate PXR-responsive reporter expression in HepG2 cells and to bind to PXR in vitro. A, HepG2 cells were transiently transfected with pSG5-hPXR1, XREM-CYP3A4-Luc, and pRL-CMV and then incubated for 24 h with (top) medium alone (UT) or containing 0.1% DMSO (DM), 0.1% methanol (MeOH), 0.3 to 10 μM squalene 2,3-oxide (SO), or 0.3 to 10 μM squalene 2,3:22,23-dioxide (SDO) or (bottom) 10 μM Ro 48-8071 (Ro), 0.1 μM NB-598 (NB), Ro and DM, or Ro and NB alone (UT) or in combination with MeOH, SO, or SDO. After treatment, cells were harvested for measurement of firefly and Renilla luciferase activities. Normalized (firefly/Renilla) values are expressed as mean ± S.D. (n = 3 wells/treatment group). Groups not sharing a letter are significantly different from each other, p < 0.05. B, the LanthaScreen TR-FRET PXR (SXR) competitive binding assay was used to evaluate the abilities of SO and SDO (left) and Ro 48-8071 (right) to interact with PXR in vitro. T0901317 was included as a positive control PXR ligand (the same binding data for T0901317 are replicated in each panel). IC50 values and 95% confidence intervals (CIs) are shown. For the Ro 48-8071 data, the IC50 value is an estimate, and CI could not be calculated.

Article Snippet: Squalene 2,3-oxide (2,3-oxidosqualene, racemic) and squalene 2,3:22,23-dioxide (2,3,22,23-dioxidosqualene, mixture of diastereomers) were purchased from Echelon Biosciences (Salt Lake City, UT).

Techniques: Concentration Assay, Expressing, In Vitro, Transfection, Incubation, Luciferase, Competitive Binding Assay, Positive Control, Binding Assay