Figure 3. FOXE1 regulates TERT transcription in thyroid cancer cells.

(A) Determination of the transcriptional activity of FOXE1 upon the TERT gene promoter. KTC1 cells were transiently transfected with either wild-type or C228T TERT-luc, and different combinations of FOXE1-Flag, FOXE1^A65V-Flag or empty Flag expression plasmids. Twenty-four hours post-transfection the cells were treated for a further 24 hours with 10 μM U0126 or vehicle, prior to whole cells lysates being harvested for luciferase reporter assays. Luciferase results are the mean (± SD) of three experiments, each performed in triplicate, expressed as fold change in luciferase activity relative to empty vector transfected cells. (B) Measurement of the changes in TERT mRNA transcription in response to depleting FOXE1 and ELK1 proteins. SW1736 cells were transiently transfected with FOXE1/ELK1 specific-siRNA (or scrambled siRNA control), then RNA and protein harvested from the cells 48 hrs later. FOXE1 and ELK1 levels were ascertained by western blotting, whilst TERT mRNA expression were quantified by real-time qRT-PCR. Significant changes are highlighted (*p < 0.05, Student’s t-test).