Apoptosis of human hepatoma cell lines induced by transforming growth factor beta 1 (TGF-beta1) correlates with p53 and Smad4 activation.
OBJECTIVE
To determine the relationships between apoptosis induced by transforming growth factor beta 1(TGF-beta1) and Smad in human hepatoma cell lines.


METHODS
Three human hepatic carcinoma cell lines, involving different status of the p53 gene respectively, were used in this study. TGF-beta1-induced apoptosis in hepatic carcinoma cell lines was quantitated using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. For identification of the mechanism of apoptosis induced by TGF-beta1, these cell lines were transfected with a TGF-beta1-inducible luciferase reporter plasmid containing Smad binding elements (SBE) and luciferase gene using LF2000, then were treated with TGF-beta1. Relative luciferase activity was assayed respectively.


RESULTS
Among three cell lines studied with TUNEL assay, addition of TGF-beta1 induced apoptosis only in HepG2 cells (wild type p53). In contrast, Huh-7 (mutant p53) and Hep3B (deleted p53) cell lines lacked apoptosis. The detection of luciferase activity indicated that HepG2 cells dramatically increased the response to TGF-beta1 induction, Huh-7 and Hep3B cell lines significantly lowered luciferase expression.


CONCLUSIONS
HepG2 cells were highly susceptible to TGF-beta1-induced apoptosis compared with Hep3B and Huh-7 cell lines. Smad4 may be a central mediator of the TGF-beta1 signaling transduction pathway.
Wang
Chun-lei
CL
Department of General Surgery, Peking University First Hospital, Beijing 100034, China. wangchunlei301@yahoo.com
Wan
Yuan-lian
YL
Liu
Yu-cun
YC
Huang
Zhi-qiang
ZQ
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D056945:Hep G2 Cells; D006801:Humans; D015398:Signal Transduction / Q000187:drug effects; D051901:Smad4 Protein / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C497796:SMAD4 protein, human; D051901:Smad4 Protein; C495901:TP53 protein, human; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53