Three-dimensional Mammary Epithelial Cell Morphogenesis Model for Analysis of TGFß Signaling.

Culturing mammary epithelial cells in laminin-rich extracellular matrices (three dimensional or 3D culture) offers significant advantages over that in the conventional two-dimensional (2D) tissue culture system in that it takes into considetation the impact of extracellular matrix (ECM) microenvironment on the proliferation, survival, and differentiation of mammary epithelial cells. When grown in the 3D culture, untransformed mammary epithelial cells undergo morphogenesis to form a multicellular and polarized acini-like structure that functionally mimics the differentiated alveoli in the pregnancy mammary gland. This process is subjected to regulation by many growth factors and cytokines. The transforming growth factor-ß (TGFß) is a multipotent cytokine that regulates multiple aspects of development and tumorigenesis. In addition to its effects on epithelial cell proliferation, survival, and differentiation, it is also a potent regulator of the cell-matrix interaction. Thus, the 3D culture model may recapitulate the complex in vivo epithelial cell microenvironment and allow us to fully evaluate the role of TGFß signaling in multiple aspects of normal and cancerous cell behavior. In this chapter we provide detailed protocols for growing mammary epithelial cells in the 3D Matrigel for analysis of signaling pathways.