Abstract: The present invention provides premalignant, serially-transplantable, hyperplastic outgrowth breast tissue lines and methods of isolating these tissue lines from mice expressing a transgene which genetically predisposes said mice to develop breast cancer. This is accomplished by implanting cells from said foci both subcutaneously and in the inguinal mammary fat pads of syngeneic, non-transgenic mice; identifying foci which grow in said fat pads but not subcutaneously as premalignant, hyperplastic outgrowths; and, establishing clonal serially-transplantable breast tissue lines from said outgrowths. Such premalignant, serially-transplantable, hyperplastic outgrowth breast tissue lines are useful for screening chemotherapeutic and chemopreventative agents as well as for identifying biomarkers of mammary preneoplasia.

Abstract: Methods and compositions are provided for identifying patients suffering from neoplastic diseases such as breast cancer. It has been found that neoplastic epithelial cells, including neoplastic mammary epithelial cells, release a particular N-terminal blocked, soluble cytokeratin into circulation. The presence of this cytokeratin is diagnostic of neoplastic disease.