Induction of epithelial abnormalities that resemble human breast lesions by the expression of the neu/erbB-2 oncogene in reconstituted mouse mammary gland.

We have developed a transplantation system that allows us to introduce oncogenes into mouse mammary epithelial cells in culture and then to reconstitute an epithelial tree in vivo from the genetically altered cells. Introduction of the neu oncogene, a transtorming homologue of the human proto-oncogene c-erbB-2, produced a variety of abnormal patterns of epithelial growth, many of which resembled lesions found in human breasts. In tour of 43 oncogene-bearing glands, areas of ductal carcinoma in situ were found, an abnormality previously observed in transgenic neu-bearing mice. Six glands developed localized areas of dense stroma containing excess ductal structures comprised of mildly hyperplastic epithelium