Figure 1.

Effects of prenyltransferase inhibitors on estrogen response element (ERE)-dependent luciferase activity (a) in stably transfected MELN cells and (b) in transiently transfected MCF-7 cells. Both MELN cells and MCF-7 cells are deprived of estradiol (E2) for 4 days, and the MCF-7 cells are transiently transfected with the ERE-β-glob-Luciferase and the Renilla luciferase plasmids. Three hours after transfection, cells were treated or not with FTI-277 (10 μM or dithiothreitol/dimethylsulfoxide vehicle). Twenty-four hours later, cells were stimulated with E2 (5 nM) or ethanol and were treated or not with FTI-277 or GGTI-298 (10 μM or 5 μM, respectively, or dithiothreitol/dimethylsulfoxide vehicle). Luciferase activity was quantified 16 hours after E2 addition, as described in Materials and methods. Results are expressed in arbitrary units after normalization. Error bars indicate the mean values ± standard deviation from triplicate experiments, and the results are representative of two independent experiments. Results obtained show that prenylation inhibitors statistically increase the luciferase activity induced by E2 compared with the activity induced by E2 alone in MELN cells only (* P < 0.02).