Transforming growth factor ? in the human prostate: Its role in stromal-epithelial interactions in non-cancerous cell culture

BACKGROUND: Stromal-epithelial interactions play a critical role in prostate development, but the precise mechanisms are still unknown. Transforming growth factor-beta (TGFbeta) could be a potential mediator of these interactions, but there is as yet no clear demonstration of its role. METHODS: Separate cultures and co-cultures of fibroblasts and epithelial human prostate cells were performed. We measured TGFbeta1 and TGFbeta2 secretion by specific ELISA assay, cell growth by DNA assay, and TGFbeta type II receptor expression by RT-PCR. RESULTS: Co-culture resulted in a 20% inhibition of epithelial cell growth, similar to that obtained after TGFbeta treatment (2 ng/ml for 48 hr), but without affecting fibroblast proliferation. This was accompanied by a five- to six-fold increase in epithelial TGFbeta2 secretion. CONCLUSIONS: These results demonstrate for the first time that TGFbeta2 secretion by prostate epithelial cells is under the direct control of a diffusible factor secreted by fibroblasts. They emphasize the role of TGFbeta in stromal-epithelial interactions.