Epithelial-mesenchymal transition in breast cancer correlates with high histological grade and triple-negative phenotype

Aims: Epithelial-mesenchymal transition (EMT) is characterized by a loss of epithelial nature and the acquisition of a mesenchymal form. The aim of this study was to assess the role of EMT in human mammary carcinogenesis, by performing immunohistochemical studies of EMT markers with tissue microarrays. Methods and results: A total of 492 cases were evaluated and classified as hormone receptor (HR)-positive type, HER2 type and triple-negative (TN) type by the use of immunohistochemistry and in-situ hybridization. We compared these groups in terms of epithelial and mesenchymal marker expression patterns. Of the 102 cases of TN-type breast cancer, 24.5% expressed vimentin, 13.7% expressed N-cadherin, and 9.8% expressed smooth muscle actin (SMA). Of the 221 cases of HR-type breast cancer, 4.1% expressed vimentin, 5.9% expressed N-cadherin, and 0.4% expressed SMA. Regarding epithelial markers, decreased expression was seen in 16.7% of cases for E-cadherin, in 45.1% for cytokeratin (CK)19 and in 60.8% for CK8 and CK18 (CAM5.2) in TN-type breast cancer cases. Decreased expression was seen in 11.8% of cases for E-cadherin, in 6.8% for CK19 and in 3.2% for CAM5.2 in HR-type cases. Conclusions: EMT features were particularly seen in TN-type breast cancer (P<0.001). EMT was also significantly associated with high histological grade (P<0.001).