Transforming growth factor-β1-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 line, 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 postulate that TGF beta 1 action is mediated through an indirect mechanism by inducing the expression of platelet-derived growth factor (PDGF), which, in turn, stimulates proliferation. The TGF beta 1-induced proliferation can be abrogated by treatment with a PDGF-neutralizing antibody. Treatment with exogenous PDGF significantly increased TSU-Pr1 proliferation. Finally, treatment of TSU-Pr1 cells with TGF beta 1 resulted in an increase in PDGF secretion. These results indicate that TGF beta 1-induced proliferation in TSU-Pr1 cells is at least mediated through an increased secretion of PDGF.