The Use of Cultured Human Mammary Epithelial Cells in Defining Malignant Progression a

Human specimens taken directly from the operating room have limited value for biochemical and molecular comparisons between tumor and normal tissues. Besides the cell type of interest, these tissues contain varying amounts of other cells including lymphocytes, blood vessels, and stromal fibroblasts, which interfere with comparisons. When attempts are made to dissociate the tissue and isolate the particular cell type of interest, usually too few cells are obtained for study. In vitro culturing to amplify the number of available cells is one approach to this dilemma. Unfortunately, only occasional tumor specimens develop into cell lines with infinite growth potential, while the vast majority of primary carcinomas and all the normal tissues do not. One notable exception is small-cell lung cancer, which routinely can be established as cell lines'; however, the normal counterpart of this malignant cell has not been cultured. Recently, some success has been reported in short-term culturing of a variety of other cell types? Our laboratory has been involved in developing techniques for short-term culture of human mammary epithelium.'-' Our goal has been to isolate and culture with high efficiency and to identify epithelial cells from every specimen regardless of stage in malignant progression. Here we describe our progress to date and illustrate how these cultures provide unique insights into the nature of malignant progression.