Cirrhotic hepatocytes exhibit decreased TGFbeta growth inhibition associated with downregulated Smad protein expression.
TGFbeta controls hepatocyte growth through cell cycle arrest and apoptosis, and resistance to TGFbeta is a mechanism of malignant transformation. The aim of this study was to assess differences in TGFbeta-mediated growth inhibition in normal and cirrhotic hepatocytes. Cirrhosis was induced in mice and normal and cirrhotic hepatocytes were isolated by collagenase perfusion and treated with or without TGFbeta (5 ng/ml). DNA synthesis, Smad protein expression, and DNA binding activity were determined. TGFbeta reduced DNA synthesis to a greater degree in normal hepatocytes than in cirrhotic hepatocytes (87% vs. 68%; p<0.05). Smad protein expression was decreased in cirrhotic hepatocytes and Smad 2/3/4 complex formation was suppressed. Furthermore, cirrhotic hepatocytes had decreased DNA binding activity at 120 min following TGFbeta treatment. In conclusion, decreased Smad protein expression may impair TGFbeta-mediated growth inhibition in cirrhotic hepatocytes.
Lange
Patricia A
PA
Division of Gastrointestinal Surgery, Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7081, USA.
Samson
Charles M
CM
Bird
Mark A
MA
Hayden
Melissa A
MA
Behrns
Kevin E
KE
D021581:Active Transport, Cell Nucleus; D000818:Animals; D015153:Blotting, Western; D002455:Cell Division; D002471:Cell Transformation, Neoplastic; D017364:Collagenases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D015536:Down-Regulation; D005355:Fibrosis; D022781:Hepatocytes / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011485:Protein Binding; D015398:Signal Transduction; D051785:Smad Proteins; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D013936:Thymidine / Q000737:chemistry; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D004268:DNA-Binding Proteins; D051785:Smad Proteins; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D004247:DNA; D017364:Collagenases; D013936:Thymidine