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, resemble human proliferative breast disease and sporadically progress to carcinoma. Basement membrane was visualized with a silver stain and myoepithelial cells detected by their reactivity with antibody against smooth muscle actin. The ducts formed in situ are bilayered, composed of both myoepithelial and luminal epithelial layers circumscribed by a distinct basement membrane. The human origins of both luminal and myoepithelial layers were confirmed with fluorescent in situ hybridization with a probe for human chromosome 9. Electron microscopic studies reveal actin bundles and the formation of hemidesmosomes bordering the basement membrane, consistent with myoepithelium, as well as the formation of desmosomes between luminal and myoepithelial cells.