Ultrastructural and Immunocytochemical Characterization of an Immortalized Human Breast Epithelial Cell Line, MCF-101

The human breast epithelial cell line MCF-10 was derived from s.c. mastectomy tissue from a 36-year-old, parous, premenopausal woman with fibrocystic disease. It was initiated as a mortal cell line (Mt '!•'KIM), which senesces when transferred serially in 1.05 HIMcalcium. These cells spontaneously gave origin to two immortal sublines, IMCF10A, or attached cells, and MCF-10F, or floating cells, which have proliferated for more than 4 years in Dulbecco's modified essential medium and Ham's F-l 2 either with the customary calcium concentration of 1.05 mivi (DMEM-H) or in medium containing 0.04 DIMcalcium or low calcium. Studies reported here indicate that MCF-10 is a mammary epithelial cell line. Electron microscopy showed that both MCF-10A and MCF-10F have characteristics of luminal ductal cells, but not of myoepithelial cells. When grown for more than 1200 days in Dulbecco's modified essential medium-Ham's F-l 2 and low calcium media, respec tively, they maintained their epithelial characteristics, although the con centration of calcium exerted a powerful influence on cell morphology. Cells grown in Dulbecco's modified Eagle's medium-Ham's F12 medium are low cuboidal with numerous desmosomes and short microvilli, whereas those grown in low calcium medium have significantly reduced number of desmosomes, are more spherical, and have greater numbers of microvilli which are longer than those of cells grown in DMEM-H. The breast epithelial origin of these cells was confirmed by immillino tochemical detection of epithelial sialomucins and keratins. The mono clonal antibodies MFA-breast and MC5 and the polyclonal antibody epithelial membrane antigen were used to detect the epithelial sialomu cins. Keratins were characterized by using KA-4, K-14, AE1/AE3, and K-19 specific antibodies. It was concluded that MCF-10A and MCF-10F cells are breast epithelial cells and that they represent an important tool for studies of the basic processes of growth and carcinogenesis.