Characteristics of FGF-receptors expressed by stromal and epithelial cells cultured from normal and hyperplastic prostates.

Three fibroblast growth factors (FGFs), acidic FGF (FGF1), basic FGF (FGF2), and keratinocyte growth factor (FGF7) have been identified in prostate. To understand how FGFs regulate growth of the prostate, and to determine if regulation is altered in benign prostatic hyperplasia (BPH), the mitogenic potential of FGFs, receptor binding, and FGF-receptor (FGFR) gene expression of stromal (PS) and epithelial cells (PE) cultured from normal human prostate and BPH where determined. FGF1 and FGF2, but not FGF7, were mitogens for PS. FGF1 and FGF7 were potent mitogens for PE, but FGF2 was a weak mitogen for these cells. Both PS and PE exhibited high affinity binding (pM K) of iodinated-FGF2. The K was 4-fold and 12-fold higher for PS than for PE cultured from normal prostate and BPH, respectively. Northern analysis indicated that PS, but not PE, expressed FGFR type 1 (FGFR1) mRNA. The reverse transcriptase polymerase chain reaction (RT-PCR) was used to evaluate FGFR type 2 (FGFR2) expression. The size of amplified DNA fragments, and nucleotide sequences, indicated that PS also expressed transcripts for the exon IIIc RNA splice variant of FGFR2. A RT-PCR product with the FGFR2 exon IIIb nucleotide sequence joined with the exon IIIc sequence was amplified with poly A+ RNA from PE and primers spanning both exons. Thus, PE did not alternatively splice mRNA for FGFR2 exon IIIb and exon IIIc. No differences in the mitogenic potential of FGFs, receptor binding (K or number of sites), or FGFR gene expression were found in cells cultured from normal prostate and BPH.