Objective: We examined the effects of transforming growth factor-beta 1 (TGF-beta 1) on intracellular parathyroid hormone-related peptide (PTHrP) production in a human ovarian cancer cell line (HOC-21).
Methods: Various concentrations of TGF-beta 1 were added to a culture medium, and the numbers of cells were counted. HOC-21 cells were cultured with or without TGF-beta 1, and intracellular PTHrP was measured by a radioimmunoassay kit that recognized the carboxy-terminal protein while counting the number of cells. Furthermore, a 125I-TGF-beta 1 binding assay was carried out. Values were analyzed statistically using an analysis of variance followed by an unpaired t-test.
Results: Five ng/ml of TGF-beta 1 inhibited the cell growth on Day 1 after plating. The TGF-beta 1 significantly (p < 0.05) stimulated intracellular PTHrP production in a time-dependent manner, also by Day 1. A 125I-TGF-beta 1 binding study revealed that HOC-21 cells expressed a high affinity for the TGF-beta 1 receptor.
Conclusion: The suppression of human ovarian cancer cell proliferation by TGF-beta 1 might be involved in the production of PTHrP.