A variety of previous investigations, using enzymatic digestion of the appropriate breast tissue, extracted normal as well as malignant breast epithelial

cells and reported distinct IWP-2 mw properties of these isolated primary cells [1–6]. It has been indicated that the culture of isolated cells from protease-digested solid tumors includes the risk of an overgrowth by fibroblasts or stromal cells [1, 7], demanding subsequent selective culture conditions. Growth of primary breast epithelial cells, also termed as human mammary epithelial cells (HMEC) [3, 4], and breast cancer-derived epithelial cells (HBCEC) is preferentially stimulated in serum-free medium conditions and thus allows selection among fibroblasts [8, 9]. The enzymatic and mechanical approach to isolate mammary

cells from tissues also SAR302503 molecular weight revealed certain mammary stem/progenitor cells in suspension culture [10, 11]. These mammary stem/progenitor cells can appear in multicellular aggregates termed as mammospheres with proliferative capacity for self-renewal and the potential to generate differentiated progeny [12]. Thus, distinct culture conditions of mammospheres provide the ability to induce differentiation into ductal, myoepithelial, and alveolar mammary cells, respectively [13]. A variety of markers, including morphology, growth properties [3–5], specific antigen and cytokeratin expression [1, 7] as well as metabolic alterations during aging [2] have been characterized in HMEC and in initially cultured breast tumor cells. For a more general detection and characterization of malignant tumor cells

in solid human tumors, a cytopathological examination and the measurement of telomerase activity was suggested [14]. Enzymatic digestion of breast tumor tissue by distinct proteases to obtain single cells and further subculture by trypsinization include non-specific proteolytic effects which may interfere with intracellular signaling mechanisms and cell cycle progression [15, 16]. Recent studies have demonstrated that the architecture of the mammary tissue requires cell adhesion Astemizole proteins, in particular E- and P-cadherins, which play an important role to maintain normal mammary cell functions and proliferation [17]. Moreover, transmembrane adhesion molecules such as integrins and their interaction with the cytoskeleton are essential for normal as well as breast cancer cells, respectively [15, 18], and the epithelial cells are highly susceptible to alterations of the extracellular matrix (ECM) [10, 16]. This suggests, however, that enzymatic degradation of parts of this sensitive ECM network may abolish distinct signaling pathways or induce a certain aberrant signal transfer in breast tumor tissue.