Keratinocyte growth factor functions in epithelial induction during seminal vesicle development.

Abstract

Development of the seminal vesicle (SV) is elicited by androgens and is dependent on epithelialmesenchymal interactions. Androgenic signal trnsmission from the androgen-receptor-positive mesenchyme to the epithellum has been postulated to involve paracrine factors. Keratinocyte growth factor (KGF), a member of the fibroblast growth factor family, is produced by stromal/mesenchl cells and acts s ally on epithal cells. Seminal vesicles (SVs) are male sex-accessory glands derived from the caudal regions of the Wolffian ducts. The development and maintenance of the SV are dependent on epithelial-mesenchymal interactions that are directed by androgens (1-4). SV morphogenesis begins on embryonic day 15 in mice (5) subsequent to the onset of testosterone production by the fetal testes (6). Fetal development of the SV is driven by androgens acting directly on the mesenchyme that induces epithelial development. The mesenchyme must initially mediate the inductive action of androgens because it is the only source of androgen receptor until day 1 postnatally, when epithelial androgen receptors are first detected (7). This conclusion is reinforced by analysis of SV inductions employing normal androgen receptor-positive SV mesenchyme and androgen receptor-negative epithelium (testicular feminization) (8). Dependence on epithelial-mesenchymal interaction continues into adulthood, as demonstrated by homotypic and heterotypic recombination experiments. SV mesenchyme is capable of inducing SV differentiation, morphologically and functionally, from epithelia isolated from any portion of the fetal Wolffian duct (3, 4), adult epididymis (9), and adult ureter and adult ductus deferens (2). Thus, both prenatal and postnatal development depends on instructive signals from the mesenchyme to the epithelium.The identification of paracrine signals that mediate these cell-cell interactions has proven elusive. Recently, a growth factor whose properties are consistent with such an effector has been identified and molecularly cloned. This factor, designated keratinocyte growth factor (KGF), is a heparinbinding growth factor and member of the fibroblast growth factor (FGF) family (FGF-7) (10). KGF is secreted by mesenchymal cells and appears to act solely on epithelial cells (11,12). The present studies were undertaken to investigate the possibility that KOF is an important mediator of the epithelial-mesenchymal interactions required for androgendependent SV development. MATERIALS AND METHODSAnimals and Orgn Culte. SVs were dissected from newborn BALB/c mice obtained from either the Cancer Research Laboratory (University of California, Berkeley) or Simonsen Laboratories (Gilroy, CA). SVs were grown in an organ culture system as described (13). Briefly, the organs were placed on Millipore filters supported on tangula metal grids in 35-mm Petri dishes (Falcon). A basal medium of Dulbecco's modified Eagle's medium (DMEM)/Ham's F-12, 1:1 (vol/vol), supplemented with insulin (10 pg/ml), transferrin (10 ,ug/ml), cholera toxin (10 ng/ml), bov...

Fibroblast growth factor-5 stimulates mitogenic signaling and is overexpressed in human pancreatic cancer: evidence for autocrine and paracrine actions

“…The IIIa splice variant yields a secreted FGF receptor that is derived of any signaling capacity. The expression of the IIIb splice variant is believed to be restricted to epithelial cell types whereas the expression of the IIIc splice variant is believed to be restricted expressed to mesenchymal cell types (Avivi et al, 1993;Gilbert et al, 1993;Orr-Urtreger et al, 1993;Yan et al, 1993;Alarid et al, 1994). Surprisingly, in the present study we found that COLO-357 cells express the IIIc splice variant of FGFR-1, but the IIIb variant of FGFR-2.…”

Pattern of keratinocyte growth factor and keratinocyte growth factor receptor expression during mouse fetal development suggests a role in mediating morphogenetic mesenchymal‐epithelial interactions

“…Fractions containing KGF activity were identified by their ability to stimulate 3H-thymidine incorporation in mouse BALB/MK epidermal keratinocytes. Stimulation of 3H-thymidine incorporation in BALB/MK cells was comparable to that elicited by human KGF (hKGF), and was blocked with KGF-specific, neutralizing monoclonal antibodies raised against rhKGF (Alarid et al, 1994; data not shown). Immunoblotting of mKGF with a carboxy-terminal peptide antiserum revealed a 25-28 kDa doublet band corresponding to hKGF purified from M426 human fibroblast-conditioned medium (Fig.…”

“…However, other experimental approaches will be required to fully define the precise nature of KGF involvement in epithelial development. In this regard, earlier cell and organ culture studies have demonstrated that KGF is a paracrine mitogen for epithelial cells from a variety of different sources (Aaronson et al, 1991;Marchese et al, 1990;Pierce et al, 1994;Rubin et al, 1989;Ulich et al, 1994), as well as a morphogen in the ductal branching morphogenesis of the neonatal mouse seminal vesicle (Alarid et al, 1994) and the neonatal rat prostate (Sugimura et al, 1993). The extension of similar studies to other organ systems will provide a powerful approach in further elucidating the multiple roles of KGF during development.…”

“…After extensive washing with equilibration buffer, KGF activity was eluted from the column using 0.6 M NaC1. KGF containing fractions were identified by monitoring 3H-thymidine incorporation into the DNA of BALB/MK mouse keratinocytes in the presence or absence of the KGF specific neutralizing monoclonal antibodies 1G4 or 2C4 (Alarid et al, 1994). Fractions containing KGF activity were pooled, concentrated a further 10-to 20-fold with a Centricon-10 microconcentrator (Amicon, Beverly, MA), and stored at -70°C for further analysis.…”

Normal and Malignant Prostate Epithelial Cells Differ in Their Response to Hepatocyte Growth Factor/Scatter Factor

“…[5][6][7] The critical function of HGF/SF-Met in early development and during organogenesis is illustrated by the expression of Met in human embryonic tissues and by the identical phenotypes of HGF/SF and Met targeted knockout mice with early placental and hepatic defects. 8 -10 Gerald Cunha and collaborators 11,12 demonstrated the reciprocal nature of interactions between the stroma and epithelium in the determination of final organ structure. Several studies have suggested that mechanisms mediating the inductive interactions between the stroma and normal epithelium may also stimulate neoplastic cells during carcinogenesis and metastasis.…”