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Effects of troglitazone on HepG2 viability and mitochondrial function.
Mark A Tirmenstein1, Catherine X Hu, Tracy L Gales
1Department 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
Summary
Troglitazone (TRO) causes liver damage by disrupting mitochondrial function in human liver cells. This drug-induced mitochondrial permeability transition leads to cell death, highlighting a key mechanism of hepatotoxicity.
Area of Science:
- Biochemistry
- Cell Biology
- Toxicology
Background:
- Troglitazone (TRO), a thiazolidinedione drug, is linked to patient hepatotoxicity.
- Understanding the cellular mechanisms of TRO-induced liver injury is crucial.
Purpose of the Study:
- To investigate the effects of TRO on mitochondrial function and cell viability in HepG2 cells.
- To elucidate the role of mitochondrial pathways in TRO-induced hepatotoxicity.
Main Methods:
- Exposure of HepG2 cells to varying concentrations and durations of TRO.
- Assays for cell viability (lactate dehydrogenase release), ATP levels, and mitochondrial membrane potential (MMP).
- Ultrastructural analysis of mitochondria and assessment of P450 metabolism and cyclosporin A effects.
Main Results:
- TRO induced concentration- and time-dependent cell death and loss of viability.
- Decreased ATP levels and mitochondrial membrane potential (MMP) were observed with TRO exposure.
- Mitochondrial changes and decreased MMP preceded cell death, and cyclosporin A offered complete protection.
Conclusions:
- TRO disrupts mitochondrial function, leading to mitochondrial permeability transition and subsequent cell death.
- These findings suggest that mitochondrial dysfunction is a key mechanism underlying TRO-induced hepatotoxicity.
- P450 metabolism is not essential for TRO to induce cell death in HepG2 cells.