Expression of E-, P-, N-cadherins and catenins in human bladder carcinoma cell lines

Purpose: Cadherins are cell surface glycoproteins that mediate Ca2+-depende nt;, hemophilic cell-cell adhesion. The classical cadherins, E-, P- and N-c adherins, are known to self-associate from their extracellular domain, whil e their cytoplasmic domain interacts with either beta-catenin or plakoglobi n (gamma-catenin), which in turn is bound to alpha-catenin that, links the complex to the actin cytoskeleton. The aim of the present study was to anal yze the expression of E-, P- and N-cadherins and catenins in human bladder carcinoma cells. Materials and Methods: Five human bladder carcinoma cell lines, representin g a variety of differentiation states, were grown in cell culture. We perfo rmed a cell aggregation assay, specific for biological cadherin activity. T he expression of cadherins and catenins was analyzed by immunocytochemistry , Western blotting and RT-PCR. The interactions between cadherins and caten ins were assessed by immunoprecipitation. Results: We observed a reduced E-cadherin expression in the poorly differen tiated and invasive-tumor derived cells. Interestingly, immunofluorescence study reveals the persistent localization of catenins at intercellular cont acts in two E-cadherin deficient cell lines (T24 and TCCSUP) which yet exhi bit an epithelial-like morphology and a calcium-dependent adhesive capacity . This suggests that other cadherin(s) are expressed in these both cell lin es. P-cadherin, another epithelial cadherin, is expressed only in E-cadheri n positive cells. On the other hand, N-cadherin is present at cell-cell bor ders in the very anaplastic cell lines, T24 and TCCSUP, and is able to link beta-catenin or plakoglobin. Conclusion: These results indicate that N-cadherin may participate in inter cellular adhesion, while facilitating bladder tumorigenesis.