Chemically induced oxidative stress disrupts the E-cadherin/catenin cell adhesion complex

The impact of xenobiotics on intercellular adhesion, a fundamental biologic al process regulating most, if not all, cellular pathways, has been sparsel y investigated. Cell-cell adhesion is regulated in the epithelium primarily by the E-cadherin/catenin complex. To characterize the impact of oxidative stress on the E-cadherin/catenin complex, precision-cut mouse liver slices were challenged with two model compounds for the generation of oxidative s tress, diamide (DA; 25-250 mu M) or t-butylhydroperoxide (tBHP; 5-50 mu M), for 6 h. At the concentrations used, neither compound elicited cytotoxicit y, as assessed by intracellular K+ content and leakage of lactate dehydroge nase into the culture media. However, a 25% reduction in non-protein sulfhy dryl levels, an indication of oxidative perturbation, was seen in liver sli ces treated with DA or tBHP. Total protein expression of E-cadherin, beta-, or alpha-catenin was not affected by challenge with DA or tBHP. A decrease of beta-catenin in the SDS-soluble fraction of slices, an indicator of the formation of the adhesion complex, was observed. Additionally, a decrease in beta-catenin interactions with E-cadherin and alpha-catenin, as assessed by immunoprecipitation and Western blot analysis, was seen. Disruption of the E-cadherin/catenin complex by tBHP, but not DA, correlated with enhance d tyrosine phosphorylation of beta-catenin. These results suggest that nonc ytotoxic oxidative stress disrupts the E-cadherin/catenin cell adhesion com plex in precision-cut mouse liver slices.