Transforming growth factor-beta 1-induced proliferation of the prostate cancer cell line, TSU-Pr1: The role of platelet-derived growth factor

The results of our previous study revealed that transforming growth factor- beta 1 (TGF beta 1) stimulated proliferation of the prostate cancer cell li ne, TSU-Pr1. This observation is unexpected, for TGF beta usually inhibits proliferation in prostate cancer cells. The present study examines possible mechanisms through which TGF beta 1 induces this proliferation. We postula te that TGF beta 1 action is mediated through an indirect mechanism by indu cing the expression of platelet-derived growth factor (PDGF), which, in tur n, stimulates proliferation. The TGF beta 1-induced proliferation can be ab rogated by treatment with a PDGF-neutralizing antibody. Treatment with exog enous PDGF significantly increased TSU-Pr1 proliferation. Finally, treatmen t of TSU-Pr1 cells with TGF beta 1 resulted in an increase in PDGF secretio n. These results indicate that TGF beta 1-induced proliferation in TSU-Pr1 cells is at least mediated through an increased secretion of PDGF.