Background: We investigated the role of the transforming growth factor beta (TGF-beta) family in the neoplastic progression of the human prostate.
Methods: Expression of TGF-beta mRNA was measured by Northern blot analysis of tissue extracts, and TGF-beta protein by immunohistochemical analysis of tissue sections. Proliferating cells were detected by their expression of Ki-67 antigen.
Results: The level of TGF-beta 1 mRNA was equal among normal prostate, benign prostatic hyperplasia (BPH), and prostate carcinoma. TGF-beta 2 mRNA was not detectable, and TGF-beta 3 mRNA was expressed 20-fold lesion in carcinoma compared to BPH and normal prostate. TGF-beta 1 protein was expressed in the stromal cells in all three tissues and TGF-beta 3 protein in the basal layer of epithelial cells, but not in carcinoma. Proliferating epithelial cells fail to express TGF-beta 3.
Conclusions: TGF-beta 1 and TGF-beta 3 are independently regulated, and carcinoma of the prostate is characterized by the loss of basal epithelial cells expressing TGF-beta 3.