Transforming growth factor beta secretion from primary breast cancer fibroblasts.

Transforming growth factor beta (TGF-beta) is a hormonally regulated growth inhibitor with autocrine and/or paracrine functions in human breast cancer. In vivo, enhanced immunohistochemical staining of extracellular TGF-beta 1 has been detected around stromal fibroblasts in response to the antiestrogen treatment. We have investigated the effects of tamoxifen on the production of TGF-beta by primary human breast fibroblast cultures in serum-free medium. Highly variable levels of mainly latent TGF-beta 1 were detected in conditioned media from both tumor and normal tissue derived fibroblasts. Hydroxy-tamoxifen was shown to increase latent TGF-beta 1 secretion in three of the eight tumor tissue-derived fibroblast cultures. Such effect of hydroxy-tamoxifen was not observed in fibroblast cultures established from normal adjacent breast tissue.