Atorvastatin induces apoptosis by a caspase-9-dependent pathway: an in vitro study on activated rat hepatic stellate cells.
BACKGROUND
Statins are shown to have cholesterol-independent properties such as anti-inflammation and immunomodulation. Activated hepatic stellate cells (HSCs) acquire the capacity to synthesize matrix proteins in damaged liver. We tested the hypothesis that atorvastatin may be capable of inducing apoptosis in HSCs.


METHODS
Primary cultures of rat HSCs were exposed to atorvastatin, mevalonic acid and U0126. Quantification of living, apoptotic and necrotic HSCs was performed by flow cytometry and laser-scan microscopy. Cell-cycle analysis was performed by flow cytometry. Pro- and anti-apoptotic factors were investigated by Western blot and electrophoresis mobility shift assay. Protease activity of caspases was calculated using a colorimetric kit.


RESULTS
Atorvastatin leads to a G2-arrest and induces apoptosis in activated HSCs. Atorvastatin-mediated apoptosis could be blocked by co-administration of mevalonic acid and U0126. No effects of atorvastatin on gene expression of CD95, CD95L, NF-kappaB, p53 and p21WAF1 could be observed. Atorvastatin-induced apoptosis in activated HSCs is related to an increased protease activity of caspase-9 and -3. Gene expression of the major proteins of the bcl-system shows that truncated Bid is involved in apoptosis mediated by atorvastatin. By blocking the extracellular signal-regulated protein kinase (ERK1/2) activation by adding U0126, we could prevent the apoptosis induced by atorvastatin. By Western blot we could not detect any change in the activation of c-jun N-terminal kinase (JNK).


CONCLUSIONS
Atorvastatin induces apoptosis in activated HSCs acting through an ERK-dependent cleavage of Bid and a highly increased protease activity of caspase-9 and -3. JNK is not involved in atorvastatin-mediated apoptosis in HSCs.
Aprigliano
Isabella
I
Department of Internal Medicine, Section of Gastroenterology and Endocrinology, University of Göttingen, Göttingen, Germany.
Dudas
Joszef
J
Ramadori
Giuliano
G
Saile
Bernhard
B
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D000069059:Atorvastatin; D015153:Blotting, Western; D053453:Caspase 9 / Q000378:metabolism*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D053222:Fas Ligand Protein / Q000032:analysis / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D006538:Heptanoic Acids / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000032:analysis / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000032:analysis / Q000378:metabolism; D011336:Probability; D011758:Pyrroles / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D051028:bcl-2-Associated X Protein / Q000032:analysis / Q000378:metabolism
D053222:Fas Ligand Protein; D006538:Heptanoic Acids; D016328:NF-kappa B; D011758:Pyrroles; D051028:bcl-2-Associated X Protein; D000069059:Atorvastatin; D048031:JNK Mitogen-Activated Protein Kinases; D053453:Caspase 9