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Objective To investigate the apoptosis induced by TGF-?1 in human hepatic carcinoma cell lines and its relationship with p53 gene and Smad. Methods Three human hepatic carcinoma cell lines which involving in various status of the p53 gene were used in this study. TGF-?1-induced apoptosis in hepatic carcinoma cell lines was measured by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. To study the mechanism of TGF-?1-induced apoptosis, these cell lines were transfected with a TGF-?1-inducible luciferase reporter plasmid containing Smad 4 binding elements (SBE) and luciferase gene using Lipofectamine 2000, then treated with TGF-?1, relative luciferase activity was assayed. Results Of three cell lines studied with TUNEL assay, TGF-?1 induced apoptosis was observed in HepG2 cells (wild type p53). Huh-7 (mutant p53) and Hep3B (deleted p53) cell lines showed less apoptosis. Luciferase activity assay indicated that the response to TGF-?1 induction in HepG2 cells was increased dramatically but was not significant in Huh-7 and Hep3B cell lines. Conclusion HepG2 cells seem to be highly susceptible to TGF-?1-induced apoptosis compared with Hep3B and Huh-7 cell lines. Smad 4 is a central mediator of the TGF-?1 signal transduction pathway.
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Objective To determine the relationships between apoptosis induced by transforming growth factor-beta 1(TGF-?1 )and caspase-3 as well as caspase-8 in liver cirrhosis mice. Methods In BALB/C mice,liver cirrhosis was induced by means of injection with 50% carbon tetrachloride for 8 weeks. Hepatocytes were isolated from normal and cirrhotic mice by means of a modified in situ collagenase solution perfusion method. The effects of caspase-3 and caspases-8 on TGF-?1-induced apoptosis were detected and compared . Results The viability of hepatocytes(isolated) from the mice by in situ two step collagenase digestion method was 95.2%. Internucleosomal(fragmented) DNA ladder was observed in TGF-?1 treated normal hepatocytes,but no obvious DNA ladder in(cirrhotic) hepatocytes was observed. The apoptotic rate in TGF-?1 treated normal hepatocytes (58.76%) was much higher than that of hepatocytes not treated with TGF-?1 (18.03%) .The apoptosis could be blocked by(Z-IETD-FMK) and(DEVD-CHO). Conclusions This study reveals that cirrhotic hepatocytes have poor response to(apoptosis) induced by TGF-?1,which indicates that inhibitory regulation of cell growth is impaired in cirrhotic hepatocytes. TGF-?1 can(induce) apoptosis of mice hepatocytes via caspase-8 and caspase-3-transducted signal(pathway).