The cyclopentenone prostaglandins (PGs), such as Delta(12)-PGJ(2) and PGA(1), are potent inhibitors of growth in a variety of cultured cells, including human epidermal cells. To clarify the mechanism of the cytotoxicity of these PGs, we examined the effects of Delta(12)-PGJ(2) On the function and expression of E-cadherin, which plays a major role in the maintenance of intercellular adhesion, in transformed human epidermal cells in culture (HSC-1). A 12-h incubation with 5 mu g/ml of Delta(12)-PGJ(2) did not affect the cell-binding activity of E-cadherin expressed in HSC-1 cells. Immunoblot analysis using a monoclonal antibody specific to human E-cadherin revealed that a 12-h incubation with 5 mu g/ml of Delta(12)-PGJ(2) induced E-cadherin expression in HSC-1 cells. Immunofluorescence using a monoclonal antibody against human E-cadherin demonstrated that E-cadherin was localized to the cell-cell contact regions in HSC-1 cells, Following a 12-h incubation with 5 mu g/ml of Delta(12)-PGJ(2), E-cadherin was also detected in a uniform pattern along cell junctions, although cell morphology was changed by the presence of cytotoxic PGs. These results suggest that the cytotoxicity of cyclopentenone PGs is related, at least in part, to E-cadherin expression in transformed human epidermal cells.