FGF9 is an autocrine and paracrine prostatic growth factor expressed by prostatic stromal cells

Polypeptide growth factors, including members of the fibroblast growth fact or (FGF) family, play an important role in the growth and maintenance of th e normal prostate. We have found that FGF9 is expressed at high levels in t he normal peripheral and transition zone of the human prostate. Analysis of FGF9 production by primary cultures of prostatic epithelial and stromal ce lls has shown that FGF9 is produced and secreted by the prostatic stromal c ells. Neither of these processes appears to be modulated by androgens. Prod uction of FGF9 by stromal cells in vivo was confirmed by immunohistochemist ry. FGF9 is a potent mitogen for both prostatic epithelial and stromal cell s in culture and is a more potent mitogen for these cells than either FGF2 or FGF7, two other FGFs expressed in the human prostate. FGF9 is an abundan t secreted growth factor that can act as both a paracrine mitogen for epith elial cells and an autocrine mitogen for stromal cells. Western blot analys is of tissue extracts from the normal and hyperplastic transition zone show s that FGF9 is present at two to threefold higher levels in the hyperplasti c transition zone. Overexpression of this paracrine and autocrine growth fa ctor may play an important tote in the epithelial and stromal proliferation in benign prostatic hyperplasia. (C)1999 Wiley-Liss, Inc.