Figure 5.

Liquiritigenin (Liq) and cosmosiin (Cos) induce reporter expression in Hs578T-ERαLuc and Hs578T-ERβLuc. Dose response curves of liquiritigenin (A) and cosmosiin (B). Hs578T-ERαLuc and Hs578T-ERβLuc were seeded in triplicate and treated with 50 ng/mL Dox for 24 hr. Cells were then treated with a range of ligand concentrations (0.15% final DMSO concentration) for 24 hr. Each plate contained DMSO, 0.1 nM E2 and 100 nM ICI 182,780 for controls. Luciferase signal was normalized to total protein in each well and expressed as a percent transactivation relative to signal obtained from saturating E2 treatment (0.1 nM). Each dose response experiment was conducted at least 3 times; data shown are from one representative experiment. EC₅₀ values are shown in Table 2. EC₅₀ values for cosmosiin could not be determined because of supramaximal reporter induction. The supramaximal induction by cosmosiin was not due to supramaximal transcription of the luciferase reporter (C). Hs578T-ERαLuc and Hs578T-ERβLuc cells were treated with 50 ng/mL Dox for 48 hr followed by treatment with DMSO (0.1%), 1 nM E2 or 1 μM cosmosiin for 4 or 24 hr. Firefly luciferase (FLuc) expression was determined by RT-PCR. RPL13A expression was used to ensure equal loading.