Isolation and characterization of an oestrogen-responsive breast-cancer cell line, EFF-3.

A novel oestrogen-responsive breast-tumour cell line, EFF-3, has been established from a pleural exudate of a patient with metastatic breast cancer. The cells show morphological and immunohistochemical features consistent with their origin from a metastatic breast carcinoma. The cells aggregate and form sheets in culture, and electron microscopy confirms the presence of cell-surface microvilli and intercellular tight junctions. The epithelial origin of EFF-3 cells was confirmed by their expression of low-molecular-weight cytokeratins and carcinoembryonic antigen. The karyotype of the cells is markedly abnormal and there are large numbers of structurally abnormal chromosomes. EFF-3 cells express oestrogen receptor, oestrogen-receptor mRNA, their growth is oestrogen-responsive, and specific genes are regulated by oestrogens. The pNR-2/pS2 and pNR-25 oestrogen-regulated mRNAs are induced 15- and 13-fold respectively by oestrogen, whereas the oestrogen-receptor and cathepsin D mRNAs are not regulated. This pattern of regulation differs from that reported previously for other cell lines. The EFF-3 cell line should be useful for studying the mechanisms involved in oestrogen-stimulated proliferation and the factors determining the regulation of specific genes by oestrogens.