Superoxide anions and hydrogen peroxide inhibit proliferation of activated rat stellate cells and induce different modes of cell death.
BACKGROUND
In chronic liver injury, hepatic stellate cells (HSCs) proliferate and produce excessive amounts of connective tissue causing liver fibrosis and cirrhosis. Oxidative stress has been implicated as a driving force of HSC activation and proliferation, although contradictory results have been described.


OBJECTIVE
To determine the effects of oxidative stress on activated HSC proliferation, survival and signalling pathways.


METHODS
Serum-starved culture-activated rat HSCs were exposed to the superoxide anion donor menadione (5-25 micromol/L) or hydrogen peroxide (0.2-5 mmol/L). Haem oxygenase-1 mRNA expression, glutathione status, cell death, phosphorylation of mitogen-activated protein (MAP) kinases and proliferation were investigated.


RESULTS
Menadione induced apoptosis in a dose- and time-dependent, but caspase-independent manner. Hydrogen peroxide induced necrosis only at extremely high concentrations. Both menadione and hydrogen peroxide activated Jun N-terminal kinase (JNK) and p38. Hydrogen peroxide also activated extracellular signal-regulated protein. Menadione, but not hydrogen peroxide, reduced cellular glutathione levels. Inhibition of JNK or supplementation of glutathione reduced menadione-induced apoptosis. Non-toxic concentrations of menadione or hydrogen peroxide inhibited platelet-derived growth factor- or/and serum-induced proliferation.


CONCLUSIONS
Reactive oxygen species (ROS) inhibit HSC proliferation and promote HSC cell death in vitro. Different ROS induce different modes of cell death. Superoxide anion-induced HSC apoptosis is dependent on JNK activation and glutathione status.
Dunning
Sandra
S
Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. s.dunning@med.umcg.nl
Hannivoort
Rebekka A
RA
de Boer
Jan Freark
JF
Buist-Homan
Manon
M
Faber
Klaas Nico
KN
Moshage
Han
H
D000165:Acridine Orange; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects*; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects*; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000633:toxicity; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D009930:Organic Chemicals; D018384:Oxidative Stress; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D018709:Statistics, Nonparametric; D013481:Superoxides / Q000633:toxicity*; D024483:Vitamin K 3 / Q000633:toxicity; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D017931:DNA Primers; D009930:Organic Chemicals; C402795:SYTOX Green; D013481:Superoxides; D024483:Vitamin K 3; D006861:Hydrogen Peroxide; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D000165:Acridine Orange