Adriamycin activates E-cadherin-mediated cell-cell adhesion in human breast cancer cells

E-cadherin-mediated cell-cell adhesion plays a crucial role in intercellular communication, which is related to the regulation of cell proliferation, differentiation, and apoptosis. Our previous study showed that decreased expression of MUC1 can induce E-cadherin-mediated cell-cell adhesion in human breast cancer cell lines proliferating in suspension without aggregation. Using such a cell line (YMB-S), we observed the effects of an anticancer agent, adriamycin, on cell-cell adhesion and expression of E-cadherin-catenin complex and MUC1. The cells showed E-cadherin-mediated cell-cell adhesion after 48 h exposure to 0.4 micromol/l adriamycin. And in these cells, expression of E-cadherin and beta-catenin mRNA obviously began to increase, while expression of MUC1 mRNA decreased, as demonstrated by Northern blot analysis. Such change in mRNA levels were followed by increases in E-cadherin and beta-catenin protein levels and a decrease in MUC1 protein level. Though expression of alpha-catenin mRNA began to increase on day 2, its protein level did not change. In immunohistochemical analysis, beta-catenin protein in untreated cells showed diffuse cytoplasmic localization, whereas beta-catenin in treated cells was present in cytoplasm with a clear submembranous localization, indicating that increased beta-catenin mainly bound with E-cadherin, participating in cell-cell adhesion. These findings show for the first time that adriamycin can induce E-cadherin-mediated cell-cell adhesion by increasing expression of E-cadherin and beta-catenin and decreasing expression of MUC1 during breast cancer cell apoptosis induced by this drug.