Hepatocyte Growth Factor Is Required for Progestin-Induced Epithelial Cell Proliferation and Alveolar-Like Morphogenesis in Serum-Free Culture of Normal Mammary Epithelial Cells

Abstract

The steroid hormones, estrogen and progesterone, are required for mammary epithelial cell proliferation and alveolar morphogenesis in vivo. We have developed a minimally supplemented, serum-free medium, collagen gel primary mammary culture system to determine the mechanism of progestin-induced proliferation and alveolar morphogenesis. In epithelial cells cultured alone, treatment with progestin (R5020) alone produced a lumen within the epithelial organoids, but did not stimulate epithelial cell proliferation. The formation of lumens was associated with increased apoptosis, targeted within the organoids. We have previously reported that in our culture system hepatocyte growth factor (HGF) increases epithelial cell proliferation and induces a tubulo-ductal morphological response. In the present report we show that treatment with HGF and progestin (R5020) further increases epithelial proliferation above that with HGF alone and also produces an alveolar-like morphology similar to that observed in vivo in response to progestin treatment. To the best of our knowledge this is the first in vitro demonstration of both progestin-induced proliferation and alveolar-like morphogenesis of normal nonpregnant mouse mammary epithelial cells in vitro. These results suggest that HGF may play a crucial role in progestin-induced proliferation and morphogenesis in vivo.

Host microenvironment in breast cancer development: Epithelial-cell–stromal-cell interactions and steroid hormone action in normal and cancerous mammary gland

“…Analysis of apoptosis in progestin-treated organoids shows that apoptotic cells are localized within the center of the epithelial organoids. This is in contrast to control-treated organoids, in which apoptotic cells are located on the outer periphery of the organoid [10]. This topographically localized apoptotic effect of R5020 within the organoid suggests that this may be the mechanism by which progestins cause lumen formation and that progestins may also play a key role in lumen formation in the mammary gland.…”

“…2a,2b). HGF was identified as the mediator of this effect, since the proliferative and morphogenic activity in FCM is completely abolished by neutralizing antibody to HGF but not by neutralizing antibodies to epidermal growth factor (EGF) or insulin-like growth factor 1 (IGF-1) [10]. Although HGF is constitutively produced by mammary fibroblasts in vitro under our culture conditions, its production is increased by treatment of such cultures with estrogen.…”

“…Using the culture system described above, we investigated stromal influences on progestin-dependent proliferation and alveologenesis in adult murine mammary epithelium [10]. We find that the synthetic progestin R5020 (promegestone) fails to induce proliferation of epithelial cells when added either by itself or with estrogen (Fig.…”

Dynamics of the Epithelium During Canalization of the Rat Ventral Prostate

“…Apoptosis has also been shown to be involved in the canalization of the mammary (Sunil et al, 2002) and submandibular salivary glands (Jaskoll et al, 2001), in which the deletion of some epithelial cells gives rise to the space occupied by the lumen. Apoptosis of interstitial cells plays a role in the remodeling mechanisms of the developing fetal lung to achieve the mature alveolar structure (Scavo et al, 1998), and in the proposed mechanism of ureter lumen formation and maturation (Kakuchi et al, 1995).…”

“…The development of body cavities and the formation of canals in tubular organs all result from the coordinated activity of cells. Apoptosis is involved in cell elimination during blastocyst cavitation and isolation of the inner cell mass (Coucouvanis and Martin, 1995) and in the canalization of hollow organs (Jaskoll et al, 2001;Sunil et al, 2002).…”