Effect of calcium on e-cadherin expression in breast-tumor cells.

E-cadherins are homophilic adhesion molecules the expression of which is tightly linked to the invasiveness and the differentiated state of the cells. E-cadherin expression seems also inversely related to the expression of vimentin, an intermediate filament implicated in the metastatic potential of some cells. In breast tumor cells MCF-7, we have previously shown that calcium influences cell growth and promotes cell differentiation. In view of the importance of cell adhesion mechanisms in cell growth and invasion, we sought to determine whether calcium affects the regulation of E-cadherin expression and modifies the relationship between E-cadherin and vimentin expression. To address this question, cells were grown at low (0.04 mM) or high (2.5 mM) concentration of calcium and cadherin and vimentin expression was assessed by flow cytometry analyses. Our results show that calcium enhances cadherin expression in cadherin positive cells and decreases vimentin expression in these cells; in cadherin negative cells, calcium only decreases the expression of vimentin. The modifications of E-cadherin and/or vimentin expression suggests that drugs that can modify intracellular calcium may contribute to overcoming the progression of breast tumor cells toward increasingly malignant phenotypes.