Heparin-Binding (Fibroblast) Growth Factor/Receptor Gene Expression in the Prostate
Heparin-binding (fibroblast) growth factors (HBGF) play both autocrine and paracrine roles in growth of normal and tumor prostate epithelial and mesenchymal cells. In the rat, expression of HBGF-1 dominates in normal tissue and slow-growing Dunning prostate tumor tissues. Both HBGF-1 and HBGF-2 are expressed in fast-growing, malignant variants of the Dunning tumor. Expression of HBGF-1 occurs in young normal prostate epithelial cells and disappears with age. Slow-growing Dunning tumor mesenchymal cells, not epithelial cells, constitutively express HBGF-1. HBGF requirement and receptor phenotype is altered in tumor epithelial cells. In contrast to IGF-1 and the Elg/Bek/Cek gene product, a candidate HBGF receptor, neither HBGF-1 nor HBGF-2 expression in normal and tumor tissues increases during androgenstimulated growth. Flg/Bek/Cek is expressed in young prostates, during androgen-stimulated growth of adult prostate, constitutively in tumors, and appears limited to the stromal cell fraction of the slow-growing tumors. Expression is elevated in the fast-growing, highly malignant tumors. Normal and slow-growing tumor epithelial cells have receptor sites for HBGF that may differ from Flg/Bek/Cek. Similar to rat prostate tissue, HBGF-1 expression dominates in young human prostate tissue. However, both HBGF-1 and HBGF-2 mRNA as well as the Flg/Bek/Cek gene are detectable in adult human prostate tissue. These differences in rat and human tissue may reflect differences in the epithelial:stromal cell ratio in prostates of the two species.
KeywordsTyrosine Adenocarcinoma Cysteine Heparin Testosterone
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