Role of transforming growth factor -α in human prostate cancer cell growth

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Abstract
Because of the influence of transforming growth factor-α (TGFα) on the cell growth in other cancer cell systems, we investigated the growth-regulatory role of TGFα in human prostate cancer cells. TGFα (5 ng/ml) stimulated LNCaP cell growth in monolayer to 60% of the level seen with dihydrotestosterone (DHT). Both DHT and TGFα increased cloning in soft agar twofold above that in controls. Metabolism of thymidine and uridine was also increased as evidenced by increased uptake of these macromolecule precursors. In addition, intracellular signalling as indicated by phosphatidyl inositol turnover was also increased by TGFα and DHT. Conditioned media contained TGFα by radioimmunoassay (RIA), transforming activity by rat kidney fibroblast (NRK) colony formation, and epidermal growth factor (EGF) receptor competable activity by radioreceptor assay. EGF receptors were present by binding assay and immunoprecipitation. These data demonstrate the presence of an autostimulatory growth loop in hormone-responsive human prostate cancer cells.