Figure 6

Groucho action in colon carcinoma derived cells. A) Western analysis of endogenous TLE expression in colon cancer cell lines. Whole cell extracts from the indicated colon cancer cell lines were analyzed by western blotting. Blots were probed with rat monoclonal antisera with pan specificity for the TLE family of proteins. Longer exposure of the blot reveals low levels of TLE protein in HCT-116 cell line (data not shown). B) Groucho activity was assessed in colon cancer cell lines. SW480, Colo320 and DLD-1 cells are type I APC mutant cells (left panels). LS174T, HCT116 and HT-29 cells are wild type APC or type II APC mutant cells (right panels). Refer to Figure 1 for the corresponding APC mutations in these cells. TOPFlash reporter plasmid was co-transfected with either a dominant negative TCF-1 expression vector (400 ng) or increasing amounts of Groucho expression vector. Luciferase activity was assayed 24 hours post transfection and activities normalized to TOPFlash reporter alone. The error bars show the standard deviation derived from three independent experiments.