Regulation of Fgf10 gene expression in the prostate

Abstract

Fibroblast growth factor 10 (FGF10) is a mesenchymal paracrine-acting factor that stimulates epithelial growth and is involved in the development of several branched organs, including the lungs, lachrymal glands and prostate. During branching morphogenesis in the lung, FGF10 is expressed in discrete areas of mesenchyme juxtaposed to branching epithelial tips. It has been proposed that paracrine factors produced in the epithelium and by differentiated stroma, such as sonic hedgehog (SHH) and transforming growth factor beta 1 (TGFbetal) regulate the discrete expression pattern of FGF10. In the prostate, FGF10 expression is also confined to the mesenchyme that surrounds growing epithelial buds. In the prostate it has been proposed that FGF10 is involved in prostatic induction and epithelial branching morphogenesis. However, little is known about how FgflO is regulated in the prostate, and the aim of this thesis was to investigate some of these regulatory mechanisms. This was done by developing a primary mesenchymal cell system in which to study FgflO regulation; investigating how TGFbetal and testosterone affect FgflO transcript expression in prostate cells and organs, and analysing the FgflO promoter. In addition the effects of TGFbetal on prostate growth were assessed to determine if TGFbetal might have opposing effects to that of FGF10.A primary stromal cell system, derived from the Ventral Mesenchymal Pad (VMP) was established and characterised. The VMP is a condensed area of mesenchyme found in both males and females that is required for prostatic induction in males, and is known to express FgflO. After the first passage in vitro, primary VMP cells (VMPC) became larger and their growth rate slowed, suggesting that primary VMPC senesced after being plated out. VMPC maintained expression of FgflO, Tgfbetal, 2, and 3 transcripts at levels similar to those in the VMP in vivo. VMPC also expressed androgen receptor but did not show androgen responsive growth in vitro. It was concluded that primary VMPC were a good cellular system in which to study the regulation of FgflO gene expression, and were used on their first passage.