Co-expression of tenascin-C and vimentin in human breast cancer cells indicates phenotypic transdifferentiation during tumour progression: correlation with histopathological parameters, hormone receptors, and oncoproteins.

Loss of epithelial morphology and the acquisition of mesenchymal characteristics are typical for carcinoma cells in tumour progression. In human breast carcinomas, up-regulation of tenascin-C (TN-C) and vimentin (Vim) is frequently observed in cancer cells and correlates with increased malignancy. Thus, it is possible that TN-C is co-expressed with Vim, representing cancer cells that have undergone epithelial-mesenchymal transition (EMT). This study examined 128 breast carcinomas using immunohistochemical techniques to demonstrate that mammary cancer cells are a prominent source of both TN-C and Vim. Statistical analysis revealed a significant association between TN-C and Vim expression in cancer cells. TN-C expression also correlated positively with overexpression of c-erbB-2 oncoprotein and down-regulation of oestrogen receptors (ERs). Eleven human mammary cancer cell lines and two 'normal' cell lines were examined by western blotting and immunohistochemistry. Co-expression of TN-C and Vim was detected in the carcinosarcoma cell line HS 578T, SK-BR-3 (B), fibroblast-like MDA-MB-231 cells, and the myoepithelial cell line HBL 100. These findings suggest that TN-C and Vim, when co-expressed in mammary carcinoma cells, represent regulator genes likely to be involved in EMT during mammary carcinogenesis.