title: Epithelial membrane polarity: a stable, differentiated feature of an established human breast carcinoma cell line MCF-7.
abstract: Carcinoma cells typically show little or no polarity as compared to normal, differentiated epithelial cells. We have studied polarity in two established human breast carcinoma cell lines, T47D and MCF-7, by various techniques (electron microscopic enzyme- and immunocytochemistry, freeze-fracture) and show that one of them (MCF-7) is characterized by a high degree of polarity. Thus, in contrast to T47D cells, MCF-7 cells in monolayer culture form apical tight junctions, do not allow a ricin-horseradish peroxidase conjugate, which binds to terminal galactose residues on the apical surface, to stain the basolateral membrane domain, and express a surface antigen (MFGM-A) only in the apical surface membrane domain, as do normal mammary epithelial cells in vivo. This polarization is independent of a basement membrane, since it is maintained when MCF-7 cells, which do not deposit type IV collagen themselves, are grown directly on plastic. Moreover, even though MCF-7 cells express estrogen receptors rather homogeneously, estrogen has no effect on this polarity, neither in vitro nor after transplantation to nude mice. We conclude that polarity is a stable, differentiated feature of MCF-7 cells.
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000032:analysis* / Q000648:ultrastructure; D002277:Carcinoma / Q000032:analysis* / Q000648:ultrastructure; D002460:Cell Line; D002462:Cell Membrane / Q000648:ultrastructure; D003896:Desmosomes / Q000648:ultrastructure; D005614:Freeze Fracturing; D006651:Histocytochemistry; D006735:Horseradish Peroxidase; D006801:Humans; D007124:Immunoenzyme Techniques; D007365:Intercellular Junctions / Q000648:ultrastructure*; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008819:Mice, Nude; D018396:Mucin-1; D009368:Neoplasm Transplantation; D012276:Ricin
chemical_list: D008565:Membrane Proteins; D018396:Mucin-1; D012276:Ricin; D006735:Horseradish Peroxidase