Increasing evidence has confirmed that ligands for peroxisome proliferator-activated receptor ␥ (PPAR␥) exhibit antitumoral effects through inhibition of cell proliferation and induction of cell differentiation in several malignant neoplasms. Recently, we have documented the accumulation of a cyclin-dependent kinase inhibitor, p27 Kip1 , as well as an unexpected accumulation in cyclin E in G1-arrested human hepatoma cells treated with the PPAR␥ ligand troglitazone. Simultaneous accumulations in both p27 Kip1 and cyclin E are known to be characteristic phenotypes in cells derived from mice lacking Skp2, an F-box protein component of the SCF ubiquitin-ligase complex. Thus, the aim of the present study was to assess whether Skp2 might be involved in the down-regulation of p27 Kip1 in troglitazone-treated human hepatoma cells. A striking decrease in Skp2 expression and a reciprocal increase in p27 Kip1 expression were found in troglitazonetreated hepatoma cells but not in those cells treated with other PPAR␥ ligands such as pioglitazone and ciglitazone. Quantitative real-time RT-PCR analysis showed that troglitazone downregulated Skp2 at the mRNA levels. Consistently, ectopic overexpression in Skp2 brought resistance to troglitazone, resulting in a decreased population of arrested cells at the G1 phase compared with that in the mock-transfected cells. In surgically resected hepatocellular carcinoma (HCC) tissue, an increased expression in Skp2 was found in both the moderately differentiated HCCs and the poorly differentiated HCCs. In conclusion, troglitazone attenuated Skp2 expression, thereby promoting p27 Kip1 accumulation in human hepatoma cells. This therapeutic potential of the ligand may lead to new cell-cycle-based antitumor strategies for advanced HCCs.

Troglitazone has been withdrawn from therapeutic options for diabetes mellitus because of its severe hepatocyte toxicity of unknown pathogenesis. The aim of the present study was to assess both morphologic and functional alterations in the mitochondria of troglitazonetreated hepatocytes. A polarized human hepatocyte cell line, OUMS-29, was used in this study. The mitochondrial volume and the mitochondrial transmembrane potential (⌬⌿ m ) were examined using flow cytometry with nonylacridine orange (NAO) and rhodamine-123, respectively. An ultrastructural examination of the troglitazone-treated OUMS-29 cells was performed using transmission electron microscopy (TEM). Reactive oxygen species (ROS) production was assessed using flow cytometry with dihydroethidium and 2 ,7 -dichlorodihydrofluorescein diacetate. A significant increase in the mitochondrial volume of the troglitazone-treated cells was found by the NAO analysis, in comparison with pioglitazone-treated and ciglitazone-treated cells. The increase in volume was due to a marked enlargement in the mitochondria. The markedly enlarged mitochondria with intramitochondrial electrondense deposits were confirmed on TEM, which showed myelin-like structures, indicating degraded membrane constituents. The troglitazone-treated cells showed a significant decline in the ⌬⌿ m per unit mitochondrial volume but resulted in no clear cell death. ROS analysis revealed a significant production of hydrogen peroxide in the troglitazone-treated hepatocytes. This production was attenuated using an antioxidant, N-acetyl-L-cysteine. In conclusion, troglitazone caused overproduction of hydrogen peroxide, which deteriorated both mitochondrial membrane structures and mitochondrial function, leading to a possible priming for the severe hepatocyte toxicity. (HEPATOLOGY 2003;37:136-147.) T roglitazone, a ligand for peroxisome proliferatoractivated receptor ␥ (PPAR␥), used to be administered as an antidiabetic drug until it was discovered to be associated with hepatotoxicity and withdrawn from the market after reports of several dozens of deaths or cases of severe hepatic failure requiring liver transplantation. 1,2 In contrast to troglitazone, 2 other glitazones, pioglitazone and rosiglitazone, are still on the market; however, several cautionary reports have suggested that the latter 2 drugs show hepatotoxicity as a class effect of glitazones. [2][3][4][5][6][7][8][9] Although the troglitazone-associated hepatotoxicity has been considered idiosyncratic direct hepatocyte toxicity, 10 the precise mechanism has remained unclear. In our recent study, mitochondrial damage was ultrastructurally demonstrated in troglitazone-treated human hepatoma cells, 11 allowing us to first focus on alterations in the mitochondrial structure and the function in the troglitazone-treated human hepatocytes. Troglitazone is known

We report a series of five patients with autoimmune hepatitis (AIH) accompanied by systemic lupus erythematosus (SLE) (AIH-SLE overlap). Serologic tests showed that all patients were positive for antinuclear antibody and double-stranded DNA antibody. Histological examination of the liver showed that three of the patients had chronic hepatitis with severe activity. One of the other two had acute and severe hepatitis with submassive necrosis in both portal and lobular areas. The last patient already had liver cirrhosis. All patients had a mild form of SLE and showed a rapid response to corticosteroid. There was no serious involvement of organs other than the liver in any of the patients, and the prognoses were comparatively good in all patients.

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