MYOFIBROBLAST AND CONCURRENT ED-B FIBRONECTIN PHENOTYPE IN HUMAN STROMAL CELLS CULTURED FROM NONMALIGNANT AND MALIGNANT BREAST-TISSUE

Primary cultures of stromal cells from non-malignant and malignant bre ast tissues contained myofibroblasts based on immunoreactivity to alph a-smooth muscle (alpha-sm) actin. The proportions of these cells were variable among cultures from non-malignant origin while consistently h igh in cultures from carcinomas. High expression of ED-B fibronectin a nd of type V collagen was observed in myofibroblast-containing culture s. While cells from nonmalignant tissues grew relatively steadily, the proliferation of carcinoma-derived cells declined during serial subcu lturing. In both types of cultures, alpha-sm actin and ED-B fibronecti n expression decreased with increasing passage numbers. Epidermal grow th factor (EGF), fibroblast growth factor b (FGFb), transforming growt h factor alpha (TGF alpha) and platelet-derived growth factor (PDGF) s howed consistent mitogenic effects. Addition of FGFb prolonged culture growth and allowed alpha-sm actin and ED-B fibronectin expression to persist. These results demonstrate similar phenotypic modulations in s tromal cells from non-malignant and malignant breast tissues that may reflect a common stromal response to various tissue injuries, includin g neoplasia.