Modulation of c‐myc Expression by Transforming Growth Factor β1 in Human Hepatoma Cell Lines

Abstract
The effects of transforming growth factor β1 (TGF‐β1) on cell proliferation of human hepatoma cell lines, PLC/PRF/5 and Mahlavu, were investigated under serum‐free conditions. DNA synthesis was strongly inhibited in the PLC/PRF/5 cells by addition of TGF‐β1 (0.5 to 4.0 ng/ml), but remained unchanged in the Mahlavu cells. Also the expression of c‐myc mRNA was suppressed by the addition of TGF‐β1 in the PLC/PRF/5 cells but not in the Mahlavu cells. These results indicate that TGF‐β1 might regulate cell growth, in part, by modulating c‐myc expression, although there is no direct proof that c‐myc expression is really relevant to DNA synthesis mediated by TGF‐β1.