T-Antigen interacts with β-catenin to activate β-catenin target gene promoters.

<p>HCT116 cells were co-transfected with the Wnt pathway reporter plasmid TOPflash construct and T-Antigen, β-catenin, or both. Cells transfected with T-Antigen or β-catenin alone increased TOPflash activity approximately 2- to 5-fold over baseline. Co-transfection with both T-Antigen and β-catenin resulted in 113-fold increase in TOPflash activity. Values are normalized to FOPflash (baseline) groups (Panel A). To measure activation of specific β-catenin targets, similar experiments were conducted using luciferase constructs containing the c-Myc (Panel B) or Cyclin D1 (Panel C) promoters. Expression of T-Antigen significantly increases c-Myc and Cyclin D1 promoter activity in HCT116 cells. This effect was potentiated by co-transfection with a β-catenin expression vector, resulting in a four- to ten-fold increase in promoter activity. **p≤0.01; ***p≤0.001.