Rachek Lyudmila I, Yuzefovych Larysa V, Ledoux Susan P, Julie Neil L, Wilson Glenn L
Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, Mobile, AL 36688, USA.
Toxicol Appl Pharmacol. 2009 Nov 1;240(3):348-54. doi: 10.1016/j.taap.2009.07.021. Epub 2009 Jul 24.
Thiazolidinediones (TZDs), such as troglitazone (TRO) and rosiglitazone (ROSI), improve insulin resistance by acting as ligands for the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma). TRO was withdrawn from the market because of reports of serious hepatotoxicity. A growing body of evidence suggests that TRO caused mitochondrial dysfunction and induction of apoptosis in human hepatocytes but its mechanisms of action remain unclear. We hypothesized that damage to mitochondrial DNA (mtDNA) is an initiating event involved in TRO-induced mitochondrial dysfunction and hepatotoxicity. Primary human hepatocytes were exposed to TRO and ROSI. The results obtained revealed that TRO, but not ROSI at equimolar concentrations, caused a substantial increase in mtDNA damage and decreased ATP production and cellular viability. The reactive oxygen species (ROS) scavenger, N-acetyl cystein (NAC), significantly diminished the TRO-induced cytotoxicity, suggesting involvement of ROS in TRO-induced hepatocyte cytotoxicity. The PPARgamma antagonist (GW9662) did not block the TRO-induced decrease in cell viability, indicating that the TRO-induced hepatotoxicity is PPARgamma-independent. Furthermore, TRO induced hepatocyte apoptosis, caspase-3 cleavage and cytochrome c release. Targeting of a DNA repair protein to mitochondria by protein transduction using a fusion protein containing the DNA repair enzyme Endonuclease III (EndoIII) from Escherichia coli, a mitochondrial translocation sequence (MTS) and the protein transduction domain (PTD) from HIV-1 TAT protein protected hepatocytes against TRO-induced toxicity. Overall, our results indicate that significant mtDNA damage caused by TRO is a prime initiator of the hepatoxicity caused by this drug.
噻唑烷二酮类药物（TZDs），如曲格列酮（TRO）和罗格列酮（ROSI），通过作为核受体过氧化物酶体增殖物激活受体γ（PPARγ）的配体来改善胰岛素抵抗。由于有严重肝毒性的报道，曲格列酮已退出市场。越来越多的证据表明，曲格列酮会导致人肝细胞线粒体功能障碍并诱导细胞凋亡，但其作用机制仍不清楚。我们推测线粒体DNA（mtDNA）损伤是曲格列酮诱导的线粒体功能障碍和肝毒性的起始事件。将原代人肝细胞暴露于曲格列酮和罗格列酮。所得结果显示，等摩尔浓度下，曲格列酮而非罗格列酮会导致mtDNA损伤大幅增加、ATP生成减少以及细胞活力降低。活性氧（ROS）清除剂N - 乙酰半胱氨酸（NAC）显著降低了曲格列酮诱导的细胞毒性，表明ROS参与了曲格列酮诱导的肝细胞细胞毒性。PPARγ拮抗剂（GW9662）并未阻止曲格列酮诱导的细胞活力下降，表明曲格列酮诱导的肝毒性与PPARγ无关。此外，曲格列酮诱导肝细胞凋亡、半胱天冬酶 - 3裂解以及细胞色素c释放。通过使用包含来自大肠杆菌的DNA修复酶内切酶III（EndoIII）、线粒体转位序列（MTS）和来自HIV - 1 TAT蛋白的蛋白转导结构域（PTD）的融合蛋白进行蛋白转导将一种DNA修复蛋白靶向线粒体，可保护肝细胞免受曲格列酮诱导的毒性。总体而言，我们的结果表明曲格列酮导致的显著mtDNA损伤是该药物引起肝毒性的主要起始因素。
