The functional unit of the breast is a double layer acinar structure composed of apical luminal cells and basal myopepithelial cells; the establishment of this structure depends on a complex network of cues provided via intracellular signaling, cell-cell communication and cell-ECM interactions.

Our laboratory in collaboration with the laboratory of Ole Peterson have recently found that myoepithelial cells have significant effects on the structure and organization of the mammary gland. Non-malignant luminal cells when cultured (without myoepithelial cells) in 3D type I collagen gels form spherical structures that lack a polarized central axis and a central lumen; however, if these same cells are cultured in 3D reconstituted basement membrane (which provides a source of laminin-1), or 3D type I collagen gels with myoepithelila cells (produce laminin-1), there is a polarized central axis with lumen formation. Interestingly, cancer derived myoepithelial cells were unable to polarize luminal cells in 3D collagen and lacked laminin-1 expression. We are currently studying the crosstalk/communication (that occurs between luminal and myoepiethelial cells) that is required for the formation of the double layer acinar structure.