Effects of troglitazone on HepG2 viability and mitochondrial function.
Troglitazone (TRO), a member of the thiazolidinedione class of drugs, has been associated with hepatotoxicity in patients. The following in vitro study was conducted to investigate the effects of TRO on mitochondrial function and viability in a human hepatoma cell line, HepG2. TRO induced a concentration- and time-dependent increase in cell death, as measured by lactate dehydrogenase release. Exposure to 50 or 100 micro M TRO produced total loss of cell viability within 5 h. Preincubation of HepG2 cells with P450 inhibitors did not significantly protect against TRO-induced cell death suggesting that P450 metabolism was not required to induce cell death. Preincubation with the mitochondrial permeability transition inhibitor, cyclosporin A, provided complete protection against TRO-induced cell death. Our results also indicated that TRO produced concentration-dependent decreases in cellular ATP levels and mitochondrial membrane potential (MMP). Ultrastructural analysis demonstrated that TRO induced mitochondrial changes at concentrations of > or =10 micro M after 2 h. Decreased MMP and altered mitochondrial morphology occurred at time points that preceded cell death and at sublethal concentrations of TRO. These observations in HepG2 cells suggest that TRO disrupts mitochondrial function, leading to mitochondrial permeability transition and cell death.
Tirmenstein
Mark A
MA
Department of Safety Assessment and Department of Safety Assessment Statistics, GlaxoSmithKline, UE0360, 709 Swedeland Road, King of Prussia, Pennsylvania 19406-0939, USA. mark_2_tirmenstein@gsk.com
Hu
Catherine X
CX
Gales
Tracy L
TL
Maleeff
Beverly E
BE
Narayanan
Padma K
PK
Kurali
Edit
E
Hart
Timothy K
TK
Thomas
Heath C
HC
Schwartz
Lester W
LW
D000255:Adenosine Triphosphate / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology*; D065607:Cytochrome P-450 Enzyme Inhibitors; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000648:ultrastructure; D010539:Permeability; D013844:Thiazoles / Q000494:pharmacology*; D045162:Thiazolidinediones; D013997:Time Factors; D000077288:Troglitazone; D014407:Tumor Cells, Cultured
D002839:Chromans; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D013844:Thiazoles; D045162:Thiazolidinediones; D000255:Adenosine Triphosphate; D000077288:Troglitazone