Objective To determine whether transforming growth factor betal （TGF-β1）/Smad signaling pathway mediates p53-dependent apoptosis in hepatoma cell lines.Methods Three human hepatic carcinoma cell lines

HepG2

Huh-7

and Hep3B

were used in this study.TGF-β1-induced apoptosis in hepatic carcinoma cell lines was analyzed using TUNEL assay.For identifying the mechanism of apoptosis induced by TGF-β1

cell lines were transfected with a TGF-β1-inducible luciferase reportor plasmid containing Smad4 binding elements.After transfection

cells were treated with TGF-β1

then assayed for luciferase activity.Results The apoptosis rate of HepG2 cell lines （48.51%± 8.21%） was significantly higher than control （ 12.72%±2.18%

P<0.05）.But TGF-β1 was not able to induce apoptosis of Huh-7 and Hep3B cell lines.The relative luciferase activity of TGF-β1-treated HepG2 cell lines （4.38） was significantly higher than control （1.00

P< 0.05）.But the relative luciferase activity of TGF-β1-treated Huh-7 and Hep3B cell lines less increased compared with control.Conclusions HepG2 cells seem to be highly susceptible to TGF-β1-induced apoptosis compared with Hep3B and Huh-7 cell lines.Smad4 is a central mediator of TGF-β1 signaling transdution pathway.TGF-β1/Smad signaling pathway might mediate p53-dependent apoptosis in hepatoma cell lines.