【Abstract】Objective To investigate the apoptosis induced by TGF-β1 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-β1-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-β1-induced apoptosis, these cell lines were transfected with a TGF-β1-inducible luciferase reporter plasmid containing Smad 4 binding elements (SBE) and luciferase gene using Lipofectamine 2000, then treated with TGF-β1, relative luciferase activity was assayed. Results Of three cell lines studied with TUNEL assay, TGF-β1 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-β1 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-β1-induced apoptosis compared with Hep3B and Huh7 cell lines. Smad 4 is a central mediator of the TGF-β1 signal transduction pathway.
Objective To explore the molecular mechanism of pathogenesis and signal pathway of platelet activation in acute respiratory distress syndrome (ARDS). Methods Thirty healthy Sprague-Dawley rats were randomly divided into 5 groups. Four groups were intravenously injected with oleic acid (OA, 0.25 ml/kg) to establish ARDS rat model. One group was intravenously injected with normal saline (NS) in same dose as control group. After injection of oleic acid for 2 h, 6 h, 24 h, 72 h in four OA groups, and injection of saline for 2 h in the control group, the rats were sacrificed. Blood was sampled from the abdominal aorta, then platelets were separated for abstracting platelet protein. The mitogen-activated protein kinase kinase 3 (MKK3) phosphorylation level in platelet was detected by Western blot method, to explore the changes of platelet mitogen activated protein kinase (MAPKs) signal transduction pathway in ARDS, and the relationship between the changes and the pathogenesis of ARDS. Results Platelet MKK3 phosphorylation level significantly increased 6-72 h after injection of oleic acid (P＜0.05). It was 2.4 times that of the control group in 6 h group (0.50±0.09vs. 0.21±0.05), peaked and 3.7 times that of the control group in 24 h group (0.78±0.06), then fell slightly but still significantly higher than the control group in 72 h group (0.75±0.13). Conclusion The activation process of platelets is related with MKK3-p38 MAPK signaling pathway in ARDS.