title: A concentration-dependent effect of ursodeoxycholate on apoptosis and caspases activities of HepG2 hepatocellular carcinoma cells.
abstract: Clinical observations suggest that ursodeoxycholate (UDCA) may protect from hepatocellular carcinoma in cirrhotic patients. Increased apoptosis of malignant cells is a candidate mechanism. Decreased apoptosis of cholangiocytes is proposed as a mechanism for the favourable effect of UDCA in primary biliary cirrhosis. We therefore studied the effects of different concentrations of UDCA on HepG2 cell proliferation, apoptosis and caspases activities. Apoptotic features and activities of the effector or initiator caspases-8, -9, -3 and -2 after treatment of HepG2 cells with different concentrations of UDCA alone or in combination with TNF-alpha were examined. Apoptosis was detected by DNA fragmentation and flow cytometric determination of apoptotic cells with Annexin-V/PI. UDCA significantly inhibits cell proliferation only at high concentrations, but increases apoptosis at low concentrations and protects from apoptosis at higher concentrations. TNF-alpha induced DNA fragmentation is potentiated by UDCA, but flow cytometry indicates protection from early apoptosis and increase in cell survival by low and intermediate UDCA concentrations. UDCA differentially activates initiator and effector caspases in different concentrations. These data demonstrate that the effect of UDCA on caspase activation and apoptosis of HepG2 cells is concentration-dependent and activation of the caspase cascade is not always translated into increased apoptosis. Serum levels of UDCA should be possibly monitored and dosage of the drug adjusted according to the required effect.
authors.affiliation: Liver Research Laboratory, School of Medicine, University of Crete, and Department of Gastroenterology & Hepatology, University Hospital of Heraklion Heraklion, Greece.
authors.forename: Nikos J
authors.initials: NJ
authors.lastname: Tsagarakis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Drygiannakis
authors.forename: Antonis G
authors.initials: AG
authors.lastname: Batistakis
authors.forename: George
authors.initials: G
authors.lastname: Kolios
authors.forename: Elias A
authors.initials: EA
authors.lastname: Kouroumalis
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D020169:Caspases / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D056945:Hep G2 Cells; D006801:Humans; D008024:Ligands; D009928:Organ Specificity; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014580:Ursodeoxycholic Acid / Q000494:pharmacology*
chemical_list: D017304:Annexin A5; D008024:Ligands; D014409:Tumor Necrosis Factor-alpha; D014580:Ursodeoxycholic Acid; D020169:Caspases