Role of Stroma-Derived Extracellular Matrix in Regulation of Growth and Hormonal Responsiveness of Normal and Cancerous Human Breast Epithelium

Abstract

REPORT DOCUMENTATION PAGEForm AGENCY USE ONLY (Leave blank)2. REPORT DATE INTRODUCTIONWhile more than 60% of breast cancers are estrogen-receptor (ER) positive, only one third of estrogen receptor-positive tumors respond to endocrine therapy (Martin et al., 1994).Understanding the mechanisms underlying the acquisition and loss of estrogen responsiveness in breast epithelium may be critical to the treatment of breast cancer since estrogen-responsive tumors have a better prognosis and are less likely to become metastatic than estrogen nonresponsive tumors (Garcia et al., 1992;Moghazy et al., 1992). In the normal mammary gland, epithelial-stromal interactions are required for steroid-induced mammary gland growth and morphogenesis. However, breast carcinogenesis is often accompanied by pronounced changes in the stroma, termed desmoplasia, or 'the stromal reaction' (Ronnov-Jessen et al., 1996). In fact, desmoplasia is a prominent feature of infiltrating ductal carcinomas, which are the most common type of breast cancer. Since desmoplastic stroma has marked changes in both cellular composition and secreted proteins, it is likely that normal epithelial-stromal interactions, essential for estrogen-mediated proliferation, are altered during breast tumorigenesis.Normal mammary epithelial cells in culture do not proliferate in response to ovarian steroids.However, mammary epithelial cells can proliferate in response to estrogen or progesterone when cultured with stromal cells or stromal-derived proteins (McGrath, 1983;Haslam, 1986; Xie and Haslam, 1997). In vivo, the surgical recombination of mature mammary stroma with immature mammary epithelium, transplanted into the mammary fat pad of an immature mouse, permits the precocious development of epithelial estrogen-inducible PR, required for branching morphogenesis (Haslam and Counterman, 1991 In our previous annual report we had found that estrogen-induced cell proliferation in MCF-7and T47D cells was modified by the attachment to ECM proteins. Specifically, laminin inhibited proliferation of both cell lines, while collagen I, collagen IV, fibronectin and vitronectin permitted estrogen-induced proliferation. We also determined that estrogen-induction of progesterone receptor in MCF-7 cells occurred on all ECM proteins, but was significantly lower on laminin. These experiments were all performed in the presence of charcoal stripped FBS.Next, serum-free culture conditions were developed that would permit estrogen-responsiveness to determine the direct effects of isolated ECM proteins, as serum contains hormones, growth These serum-free conditions were also used to determine if ECM proteins altered estrogeninduced progesterone receptor in MCF-7 cells. Similar to serum-containing media, E-induced progesterone receptor occurred on all ECM proteins, except laminin. In contrast to proliferation experiments in the absence of serum, we found that estrogen stimulated progesterone receptor expression to the same extent in the absence of serum as in the presence of serum, when ...

Enhanced cryopreservation of MSCs in microfluidic bioreactor by regulated shear flow

“…The cryopreservation associated phase changes often results into osmotic stress that lead to damage to top sites of cellular interaction. In addition, the cells adhered to substrate are more susceptible to intracellular ice formation (ICIF) as compared to suspended cells in absence of intracellular interaction 9 .…”