BACKGROUND The present review summarizes the cellular action of TGF‐β in benign and malignant growth of the prostate. METHODS. TGF‐β is a pleiotropic growth factor. It plays an important role in the regulation of growth and differentiation in many cells. In benign prostatic epithelia, its action is mediated through a paracrine mechanism. It inhibits proliferation and induces apoptosis in prostatic epithelia. It provides a mechanism to maintain epithelial homeostasis in the prostate. In prostatic stroma, its continual action leads to smooth muscle differentiation. This effect of TGF‐β may regulate the development of prostatic smooth muscle nodules in benign prostatic hyperplasia. RESULTS As prostatic epithelial cells undergo malignant transformation, two major events occur regarding TGF‐β action. These include the loss of expression of functional TGF‐β receptors and overproduction of TGF‐β in malignant cells. The loss of expression of functional TGF‐β receptors provides a growth advantage to cancer cells over their benign counterparts. The overproduction of TGF‐β by cancer cells has a multitude of adverse consequences. TGF‐β can promote extracellular matrix production, induce angiogenesis, and inhibit host immune function. The biological consequence of these activities is an enhanced tumorigenicity in prostate cancer. Results of our recent studies with a rat prostate cancer model suggest that the immunosuppressive effect of TGF‐β seems to be the primary cause of tumor progression. This is because, if these cancer cells were engineered to reduce the production of TGF‐β, tumor growth was inhibited in syngeneic hosts but not in immune compromised hosts. CONCLUSIONS Our future research should take advantage of this knowledge to devise therapeutic strategies aimed at eradicating prostate cancer. Prostate 39:285–290, 1999. © 1999 Wiley‐Liss, Inc.

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