Transforming growth factor-β1 and renal cell cancer:: Cell growth, mRNA expression and protein production of cytokines

Purpose: We evaluated the effects of transforming growth factor-beta1 (TGF-beta1) on growth activity, cytokine mRNA expression and cytokine protein production by renal cancer cells. Materials and Methods: Exogenous continuous exposure of biologically active TGF-beta1 was performed on ACHN cells at various concentrations of 0.1 to 30 ng./ml. and the number of cells was counted each culture day. To determine the index of S-phase cells the bromodeoxyuridine pulse labeling method was used. Reverse transcriptase-polymerase chain reaction (PCR) was done and PCR products were quantified. Each supernatant cytokine level was measured using an enzyme-linked immunosorbent assay. Results: TGF-beta1 significantly inhibited the growth activities of ACHN cells compared with controls. Bromodeoxyuridine labeling indexes after treating ACHN cells with TGF-beta1 (10 ng./ml.) showed that it began to decrease gradually after 24 hours and after 72 hours it was inhibited to approximately 40% compared with controls. The mRNA of TGF-beta1, TGF-beta types 1 and 2 receptors, interleukin-6 (IL-6) and granulocyte-macrophage colony-stimulating factor (GM-CSF) from ACHN cells was detected by reverse transcriptase-PCR assay. IL-6 and GM-CSF proteins were produced constitutively from ACHN cells but other cytokines were not. Adding TGF-beta1 to the cell culture medium did not influence mRNA expression, or the protein production of IL-6 or GM-CSF. Conclusions: The inhibition of growth activities of ACHN cells by TGF-beta1 are mediated by its direct binding to specific receptors on ACHN cells followed by cell cycle inhibition, while TGF-beta1 seems to have no effect on the production of the cytokines studied.