Fig. 3.

TTP overexpression represses ERα, PR, GR and AR transactivation in MCF-7 cells. Human breast cancer MCF-7 cells were transiently transfected with empty pCMV-3TAG vector (control) or with 0.25 μg of pCMV-3TAG-TTP (FLAG-TTP) along with the corresponding luciferase reporter vector. The effect of TTP on nuclear hormone receptors transactivation was determined by assay of luciferase activity, as described under “Experimental Procedures.” Assays were performed in triplicate in three independent experiments in the presence (white bars) or absence (black bars) of the corresponding nuclear receptor ligands (17β-estradiol for ERα, progesterone for PR, 5α-Androstan-17β-ol-3-on for AR and dexamethasone for GR. The results are represented as mean ± S.E. Differences in ERα activity between control MCF-7 cells and TTP-expressing MCF-7 cells are statistically significant (p < 0.05).