Primary cirrhotic hepatocytes resist TGFbeta-induced apoptosis through a ROS-dependent mechanism.
OBJECTIVE
The cirrhotic liver manifests dysregulated hepatocyte growth by poor regenerative capacity, formation of regenerative nodules, and malignant transformation to hepatocellular carcinoma. The purpose of this study was to determine if dysregulated hepatocyte growth occurs through deficient apoptosis.


METHODS
Hepatocytes were isolated from normal and CCl(4)-treated mice and treated with TGFbeta, TNFalpha, and UV-C, known apoptotic agents.


RESULTS
Cirrhotic hepatocytes were less sensitive to TGFbeta- (45+/-5 vs. 15+/-3%; P<0.003), TNFalpha- (59+/-21 vs. 21+/-8%; P=0.02), and UV-C-induced (31+/-4 vs. 17+/-4%; P<0.03) apoptosis compared to normal hepatocytes. In normal hepatocytes, TGFbeta-induced apoptosis occurred through a ROS-, MPT-, and caspase-dependent pathway. Cirrhotic hepatocytes lacked caspase activation, had decreased procaspase-8 expression, failed to undergo the MPT, and had increased basal ROS activity compared to normal hepatocytes. After treatment with trolox, an antioxidant that reduced basal ROS activity, cirrhotic hepatocytes underwent apoptosis in response to TGFbeta treatment.


CONCLUSIONS
These findings suggest that increased ROS activity in cirrhotic hepatocytes plays a critical role in mediating cirrhotic hepatocyte resistance to apoptosis. Cirrhotic hepatocyte resistance to TGFbeta-induced apoptosis is ROS-dependent and is a mechanism of dysregulated growth in the chronically inflamed liver.
Black
Dalliah
D
Division of Gastrointestinal Surgery, Department of Surgery, University of North Carolina, 320 Medical Wing E, Chapel Hill, NC 27599-7081, USA.
Bird
Mark A
MA
Samson
Charles M
CM
Lyman
Suzanne
S
Lange
Patty A
PA
Schrum
Laura W
LW
Qian
Ting
T
Lemasters
J J
JJ
Brenner
David A
DA
Rippe
Richard A
RA
Behrns
Kevin E
KE
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002252:Carbon Tetrachloride Poisoning / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D018929:Cell Culture Techniques; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D008106:Liver Cirrhosis, Experimental / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008930:Mitochondria, Liver / Q000187:drug effects / Q000502:physiology; D010539:Permeability; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta; D020169:Caspases