COEXPRESSION OF TENASCIN AND FIBRONECTIN IN EPITHELIAL AND STROMAL CELLS OF BENIGN LESIONS AND DUCTAL CARCINOMAS IN THE HUMAN BREAST

Tenascin (TN)-C and fibronectin (FN), which are glycoproteins of the e xtracellular matrix (ECM), are up-regulated in cancer tissues, includi ng breast cancer. For assessment of their involvement in cancer invasi on, it is important to know which cells are responsible for their prod uction and secretion. The distribution of cells expressing TN and FN m RNAs in benign and malignant human breast tissues was therefore analys ed by in situ hybridization, using digoxigenin-labelled cRNA probes, i n addition to demonstrating the proteins immunohistochemically. Both m RNAs mere expressed in epithelial cancer as well as in stromal cells i n a large fraction of the tumours, with co-expression in individual ce lls. In cancers with intraductal components and/or those consisting of large nests, the mRNAs were more often expressed in the cancer than i n the stromal cells. In scirrhous carcinomas, in contrast, the stromal cells were almost always positive for TN and FN mRNAs, white the canc er cells only rarely exhibited TN or FN expression. In benign lesions including adenosis, fibroadenoma and intraductal papilloma, the expres sion patterns also varied. These findings indicate that TN and FN co-e xpressed by cancer cells and stromal cells are probably involved in th e intraductal extension and early invasion of cancer cells and in the remodelling of cancer stroma. (C) 1997 by John Wiley & Sons, Ltd.