Metformin protects rat hepatocytes against bile acid-induced apoptosis.
BACKGROUND
Metformin is used in the treatment of Diabetes Mellitus type II and improves liver function in patients with non-alcoholic fatty liver disease (NAFLD). Metformin activates AMP-activated protein kinase (AMPK), the cellular energy sensor that is sensitive to changes in the AMP/ATP-ratio. AMPK is an inhibitor of mammalian target of rapamycin (mTOR). Both AMPK and mTOR are able to modulate cell death.


OBJECTIVE
To evaluate the effects of metformin on hepatocyte cell death.


METHODS
Apoptotic cell death was induced in primary rat hepatocytes using either the bile acid glycochenodeoxycholic acid (GCDCA) or TNFα in combination with actinomycin D (actD). AMPK, mTOR and phosphoinositide-3 kinase (PI3K)/Akt were inhibited using pharmacological inhibitors. Apoptosis and necrosis were quantified by caspase activation, acridine orange staining and Sytox green staining respectively.


RESULTS
Metformin dose-dependently reduces GCDCA-induced apoptosis, even when added 2 hours after GCDCA, without increasing necrotic cell death. Metformin does not protect against TNFα/ActD-induced apoptosis. The protective effect of metformin is dependent on an intact PI3-kinase/Akt pathway, but does not require AMPK/mTOR-signaling. Metformin does not inhibit NF-κB activation.


CONCLUSIONS
Metformin protects against bile acid-induced apoptosis and could be considered in the treatment of chronic liver diseases accompanied by inflammation.
Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Titia E
TE
Woudenberg-Vrenken
Laura
L
Conde de la Rosa
Manon
M
Buist-Homan
Klaas Nico
KN
Faber
Han
H
Moshage
D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001647:Bile Acids and Salts / Q000378:metabolism / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005999:Glycochenodeoxycholic Acid / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis / Q000188:drug therapy; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
D055372:AMP-Activated Protein Kinases; D001647:Bile Acids and Salts; D053148:Caspase 3; D005999:Glycochenodeoxycholic Acid; D007004:Hypoglycemic Agents; D008687:Metformin; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases