Dose dependent and divergent effects of superoxide anion on cell death, proliferation, and migration of activated human hepatic stellate cells.
OBJECTIVE
Activated myofibroblast-like cells, originating from hepatic stellate cells (HSC/MFs) or other cellular sources, play a key profibrogenic role in chronic liver diseases (CLDs) that, as suggested by studies in animal models or rat HSC/MFs, may be modulated by reactive oxygen intermediates (ROI). In this study, human HSC/MFs, exposed to different levels of superoxide anion (O(2)(.-)) and, for comparison, hydrogen peroxide (H(2)O(2)), were analysed in terms of cytotoxicity, proliferative response, and migration.


METHODS
Cultured human HSC/MFs were exposed to controlled O(2)(.-) generation by hypoxanthine/xanthine oxidase systems or to a range of H(2)O(2) concentrations. Induction of cell death, proliferation, and migration were investigated using morphology, molecular biology, and biochemical techniques.


RESULTS
Human HSC/MFs were shown to be extremely resistant to induction of cell death by O(2)(.-) and only high rates of O(2)(.-) generation induced either necrotic or apoptotic cell death. Non-cytotoxic low levels of O(2)(.-), able to upregulate procollagen type I expression (but not tissue inhibitor of metalloproteinase 1 and 2), stimulated migration of human HSC/MFs in a Ras/extracellular regulated kinase (ERK) dependent, antioxidant sensitive way, without affecting basal or platelet derived growth factor (PDGF) stimulated cell proliferation. Non-cytotoxic levels of H(2)O(2) did not affect Ras/ERK or proliferative response. A high rate of O(2)(.-) generation or elevated levels of H(2)O(2 )induced cytoskeletal alterations, block in motility, and inhibition of PDGF dependent DNA synthesis.


CONCLUSIONS
Low non-cytotoxic levels of extracellularly generated O(2)(.-) may stimulate selected profibrogenic responses in human HSC/MFs without affecting proliferation.
Novo
E
E
Università degli Studi di Torino, Dip Medicina e Oncologia Sperimentale, C so Raffaello 30, 10125 Torino, Italy.
Marra
F
F
Zamara
E
E
Valfrè di Bonzo
L
L
Caligiuri
A
A
Cannito
S
S
Antonaci
C
C
Colombatto
S
S
Pinzani
M
M
Parola
M
M
D017209:Apoptosis / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013481:Superoxides / Q000378:metabolism / Q000494:pharmacology*
D024042:Collagen Type I; D013481:Superoxides; D006861:Hydrogen Peroxide; D048049:Extracellular Signal-Regulated MAP Kinases