MULTIPOTENT HUMAN BREAST STEM-CELL LINE MCF1OAT

Human breast epithelial MCF10AT cells injected with Matrigel into the subcutis of nude/beige mice form simple ducts which, with time, resemb le human proliferative breast disease and sporadically progress to car cinoma. Basement membrane was visualized with a silver stain and myoep ithelial cells detected by their reactivity with antibody against smoo th muscle actin. The ducts formed in situ are bilayered, composed of b oth myoepithelial and luminal epithelial layers circumscribed by a dis tinct basement membrane. The human origins of both luminal and myoepit helial layers were confirmed with fluorescent in situ hybridization wi th a probe for human chromosome 9. Electron microscopic studies reveal actin bundles and the formation of hemidesmosomes bordering the basem ent membrane, consistent with myoepithelium, as well as the formation of desmosomes between luminal and myoepithelial cells.