The current study was undertaken, using cultures of prostatic epithelial and stromal cells, to determine the functional interactions between androgens, basic fibroblast growth factor (FGF2) and transforming growth factor-β1 (TGFβ1) and their importance in maintaining stromal homeostasis. Treatment of stromal cells with TGFβ1 significantly increased intracellular FGF2 and FGF2 sequestered to the extracellular matrix. FGF2 was also detected in stromal conditioned medium (SCM), but at levels 70-fold less than found in cell lysates. TGFβ1 (0·1 ng/ml) treatment caused an initial increase of 86% in secreted FGF2 levels, but high concentrations of TGFβ1 (5 ng/ml) decreased FGF2 levels by 38%, relative to the untreated control. Further studies showed that epithelial conditioned medium (ECM), androgen-treated, stromal conditioned medium (ASCM), but not SCM were mitogenic for stromal cells. Both ECM and ASCM caused a threefold increase in DNA synthesis. FGF2 may be the mediator of these interactions, since the mitogenic effect of both ECM and ASCM was significantly reduced by the addition of anti-FGF2 neutralising antibody. We hypothesise that the lack of response of stromal cells to SCM is due to TGFβ1 blocking the mitogenic effect of FGF2. Thus down-regulation of TGFβ1 synthesis, by androgens, results in stromal proliferation by ASCM.
Journal of Endocrinology (1996) 151, 315–322