Yukiko Saitou

15-Deoxy-Δ-12-14-PGJ2 regulates apoptosis induction and nuclear factor-κB activation via a peroxisome proliferator-activated receptor-γ-independent mechanism in hepatocellular carcinoma

The peroxisome proliferator-activated receptor-γ (PPARγ) high-affinity ligand, 15-deoxy-Δ-12,14-PGJ2 (15d-PGJ2), is toxic to malignant cells through cell cycle arrest and apoptosis induction. In this study, we investigated the effects of 15d-PGJ2 on apoptosis induction and expression of apoptosis-related proteins in hepatocellular carcinoma (HCC) cells. 15d-PGJ2 induced apoptosis in SK-Hep1 and HepG2 cells at a 50 μm concentration. Pretreatment with the pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethyl ketone (2-VAD-fmk), only partially blocked apoptosis induced by 40 μm 15d-PGJ2. This indicated that 15d-PGJ2 induction of apoptosis was associated with a caspase-3–independent pathway. 15d-PGJ2 also induced down-regulation of the X chromosome-linked inhibitor of apoptosis (XIAP), Bclx, and apoptotic protease-activating factor-1 in SK-Hep1 cells but not in HepG2 cells. However, 15d-PGJ2 sensitized both HCC cell lines to TNF-related apoptosis-induced ligand–induced apoptosis. In SK-Hep1 cells, cell toxicity, nuclear factor-κB (NF-κB) suppression, and XIAP down-regulation were induced by 15d-PGJ2 treatment under conditions in which PPARγ was down-regulated. These results suggest that the effect of 15d-PGJ2 was through a PPARγ-independent mechanism. Although cell toxicity was induced when PPARγ was down-regulated in HepG2 cells, NF-κB suppression and XIAP down-regulation were not induced. In conclusion, 15d-PGJ2 induces apoptosis of HCC cell lines via caspase-dependent and -independent pathways. In SK-Hep1 cells, the ability of 15d-PGJ2 to induce cell toxicity, NF-κB suppression, or XIAP down-regulation seemed to occur via a PPARγ-independent mechanism, but in HepG2 cells, NF-κB suppression by 15d-PGJ2 was dependent on PPARγ.

Ticlopidine induced acute cholestatic hepatitis complicated with pure red cell aplasia.

To the Editor: A 69-year-old man was admitted to our hospital because of general malaise, anorexia, jaundice and pruritus. He was given ticlopidine because of a cerebral infarction, after which, he presented with the above symptoms. Blood chemistries showed liver dysfunction and hyperbilirubinemia alanine transaminase (ALT), 455IU/L; asparate transaminase (AST), 190IU/l; total bilirubin, 8.2mg/dl; -glutamyltranspeptidase ( -GTP), 806IU/L. Serological analysis was negative for HBsAg, HBsAb, HBeAg, HBeAb, IgMHBc Ab, HCV Ab, and IgM-HA Ab. Anti-nuclear antibody was negative. An abdominal ultrasound scan showed normal liver and no evidence of obstructive jaundice. The patient was diagnosed with acute intrahepatic cholestasis induced by ticlopidine. Ticlopidine was discontinued, and the liver enzymes and Tbilirubin levels improved. However, a normocytic, normochronic anemia gradually developed, and reticulocytes disappeared. On the 16th day after admission, bone marrow smears showed marked depletion in the erythroblastic series (0.7%), with no abnormality in the granulocytic and megakaryocytic series. Based on these findings, the patient was diagnosed as having pure red cell aplasia (PRCA). As his hemoglobin concentration decreased rapidly, 5 units (2000 ml) of packed red cells were administered. Although no other treatment was given for anemia, hypoplasia of the erythroblastic series was transient and the anemia gradually improved. On the 35th day after admission, bone marrow smears showed improved eryhroblastic bone marrow series .Reticulocytes in the peripheral blood (5.2%) were present. On the 43rd day after admission, laparoscopy and biopsy of the liver was performed. Intrahepatic cholestasis was observed. The patient was diagnosed with acute intrahepatic cholestasis associated with pure red cell aplasia due to ticlopidine. Ticlopidine is widely used for cerebrovascular or cardiovascular disease. Adverse effects of ticlopidine include allergic skin rash, gastrointestinal symptoms (nausea etc), bone marrow toxicity, and elevation of liver function tests. Ticlopidine induced mild elevations in serum liver enzymes are observed in some studies with a 1% to 2% incidence. The incidence of severe hepatitis is estimated at 0.0013%. Only a few cases of a severe cholestatic pattern of liver injury have been reported. In such cases, liver biopsies demonstrated centro-acinar cholestasis. In our case, liver biopsy showed intrahepatic cholestasis, compatible with a druginduced liver damage. PRCA is an uncommon disease. It is almost always associated with a recent viral disease, although multiple causes have been described as a result of exposure to drugs or chemicals, infections, thymoma, or Adult Still Disease. Reports associated PRCA with lamivudine, HCV infection, and acute hepatitis A. The exact mechanism that causes the disorder is unknown, possibly associated with the immune system. Possible mechanisms for PRCA include IgGmediated destruction in the presence of the offending drug and a direct effect on DNA synthesis. Autoantibody mechanisms also were proposed for the druginduced blood cell dyscrasias. The diagnosis of PRCA in this patient was based on the progression of normocytic, normochromic anemia with normal megakaryocyte and leukocyte counts and an absence of erythroid precursors. Ticlopidine induced acute cholestatic hepatitis complicated with pure red cell aplasia is rare.

Matrix metalloproteinase, hepatocyte growth factor, and tissue inhibitor of matrix metalloproteinase during human liver regeneration

To the editor: We read with great interest the article ‘Expression of matrix metalloproteinase (MMP)-2 and 14 persists during early resolution of experimental liver fibrosis and might contribute to fibrolysis by Zhou et al. (1). This article focused on MMP for liver collagen degradation. On the other hand, recent report (2) also showed the interesting strategy that MMP and tissue inhibitor of metalloproteinases-1 (TIMP-1) regulate hepatic growth factor (HGF) release from extracellular matrix and control hepatocyte cell cycle. These studies with previous findings suggested that MMP and TIMP play important roles in not only hepatic fibrosis but also extracellular matrix remodeling in rodent liver regeneration, because proteolytic degradation of the extracellular matrix is an essential feature of tissue remodeling (3–7). cDNA microarray analysis also revealed the upregulation of many ECM-related genes in mouse hepatectomy models (8). However, the clinical significance of MMP and TIMP during human liver regeneration is still unclear. Therefore, we investigated plasma HGF, MMP-2, MMP-9, and TIMP-1 concentrations during human liver regeneration in 11 healthy