Transforming growth factor-β (TGF-β) is growth inhibitory to many malignant cells, including prostate cancer cells. The present study reports an unusual observation in that TGF-β is growth stimulatory to a human prostate cancer cell line, TSU-Pr1. The TSU-Pr1 line is highly aggressive and exhibits a rapid rate of proliferation in culture. These cells underwent further proliferation in response to TGF-β1. Both type I and II receptors to TGF-β (TβR-I, TβR-II) are expressed in TSU-Pr1 cells. Activation of a luciferase reporter gene, which contains a TGF-β response element, confirmed that the TGF-β receptors in TSU-Pr1 cells were functional. RT-PCR analysis and an ELISA assay determined that TSU-Pr1 cells secreted TGF-β. In conclusion, TSU-Pr1 cells contain functional TGF-β receptors but instead of the usual growth inhibition by TGF-β1, these cells undergo proliferation. The present observation provides a proliferative role of TGF-β in TSU-Pr1 cells, which may play a part in the aggressive phenotype of these cells and, perhaps other prostate cancer cells.
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