Interaction of rat mammary epithelium with extracellular matrix components

Primary cultures of rat mammary epithelium synthesize the basement membrane components type IV collagen and laminin and utilize these components for attachment and growth. These cells may interact with matrix components via specific cell surface receptors. However, neither laminin nor type IV collagen alone can sustain mammary differentiation or promote culture longevity in vitro. We have developed a system for the culture of mammary cells on matrices derived from rat mammary glands. This complex matrix promotes cell growth, differentiation, and hormonal responsiveness. Although the mechanisms responsible for these effects are still unknown, one possibility is that cell surface matrix receptors interact with cytoskeletal components leading to alterations in cell shape and hormone receptor configurations. The mammary gland provides an excellent model system to study the interaction of extracellular matrix components with soluble signals, e.g. hormones and growth factors, in the control of cell growth and differentiation. The way these components may interact to influence cell behavior is depicted schematically in Fig. 5.