Mesenchymal-Epithelial Interactions in Normal and Malignant Mammary Cells

Mesenchymal-epithelial interactions play a major role in embryogenesis and in fetal organ development (1). The structural integrity and function of normal adult tissue is also dependent on these interactions, which are probably mediated by the extracellular matrix between the two tissues (2). Abnormal mesenchymal-epithelial relationships have been associated with abnormal development and carcinogenesis (3). In addition, evidence is accumulating to support the concept that the mesenchyme of individuals at high risk for cancer have unique properties (4–8). A large literature provides a foundation that supports these conclusions.