Attenuation of β-catenin signaling increases susceptibility to anti-Fas–mediated apoptosis.

(A) Inhibition of β-catenin signaling by dominant-negative β-catenin, dominant-negative TCF, and E-cadherin. Jurkat cells (2 × 10⁷) were transfected with either the empty pcDNA4 vector control, dominant-negative β-catenin, dominant-negative TCF, or E-cadherin and cotransfected with pTOPFLASH or pFOPFLASH (10 μg each). Following transfection, the cells were incubated for 18 hours and luciferase reporter activity was measured as described in “Materials and methods.” (B-D) Effect of attenuating β-catenin signaling on anti-Fas–induced apoptosis. Jurkat cells were transfected with either pcDNA4 vector control or with dominant-negative β-catenin (B), E-cadherin (C), or dominant-negative TCF (D) at the concentrations indicated. The pEGFP expression vector was cotransfected for identification of transfected cells. Quantitative analysis of apoptosis induced by anti-Fas in GFP-positive Jurkat cells was performed by flow cytometry. Values represent the mean ± SD of 3 separate experiments.