15-deoxy-delta(12-14)-prostaglandin-j2 and Carcinoma--Hepatocellular

Chronic hepatitis B virus (HBV) infection is the most common cause of hepatocellular carcinoma (HCC) worldwide. This study investigated the antineoplastic effects of intrinsic and extrinsic peroxisome proliferator-activated receptor gamma (PPARgamma) ligands against HBV-associated HCC cells in vitro. Four cell lines that were established from patients with HBV-associated HCC were used. The cells were cultured in various concentrations of the following PPARgamma ligands: troglitazone, pioglitazone, rosiglitazone and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)). Cell proliferation, cell cycle and apoptosis were analyzed. PPARgamma was expressed in all the cell lines studied. Among the PPARgamma ligands, pioglitazone and 15d-PGJ(2) clearly inhibited the HBV-associated HCC cell growth and increased the proportion of cells in the sub-G1 phase in the cell-cycle analysis. In apoptosis assays, DNA fragments increased significantly, and the activities of caspase-3 and -9 also increased. A pan-caspase inhibitor and a caspase-3 inhibitor suppressed the PPARgamma ligand-induced apoptosis in a dose-dependent manner. These two PPARgamma ligands decreased the expression of bcl-2 in most of the cell lines studied. The results suggest that pioglitazone and 15d-PGJ(2) have antineoplastic effects on HBV-associated HCC cells. Both of these PPARgamma ligands could be candidates for cancer prevention or the chemotherapy of HBV-associated HCC.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Proliferation; Hepatitis B virus; Humans; Hypoglycemic Agents; Immunologic Factors; Ligands; Liver Neoplasms; Pioglitazone; PPAR gamma; Prostaglandin D2; Thiazolidinediones

Liver fibrosis can be induced by environmental chemicals or toxicants, and finally stimulates fibrogenic cytokines expression, such as transforming growth factor-beta (TGF-beta) and its downstream mediator connective tissue growth factor (CTGF). 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is a metabolite of arachidonic acid, can act as a peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, and function as either anti-inflammatory or inflammatory agents in different cell types. In this study, CTGF was detected in three human hepatoma cell lines, Hep3B, HepG2, and Huh-7, and it was up-regulated by TGF-beta. 15d-PGJ(2) significantly inhibited TGF-beta-induced CTGF protein and mRNA expressions, and promoter activity in hepatoma cells. 15d-PGJ(2) suppressed TGF-beta-induced Smad2 phosphorylation, however enhancing the phosphorylation of ERK, c-Jun N-terminal kinase (JNK), and p38 in TGF-beta-treated Hep3B cells. Other PPAR ligands like the PPARgamma agonist, troglitazone; the PPARalpha agonist, Wy-14643, and bezafibrate were also able to inhibit TGF-beta-induced CTGF. The results suggest that 15d-PGJ(2) inhibits TGF-beta-induced CTGF expression by inhibiting the phosphorylation of Smad2, which is independent of PPAR, and 15d-PGJ(2) might also act through a PPAR-dependent mechanism in human hepatoma cells. 15d-PGJ(2) might have a beneficent effect on prevention of liver fibrosis induced by environmental toxicants.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Survival; Connective Tissue Growth Factor; Fibrosis; Gene Expression; Hepatic Stellate Cells; Hepatocytes; Humans; Immunologic Factors; Liver Cirrhosis; Phosphorylation; Prostaglandin D2; RNA, Messenger; Smad2 Protein; Transforming Growth Factor beta; Up-Regulation

15-deoxy-Delta12,14-prostaglandin J2 (15-d-PGJ2) is a dehydration product of PGD2. This compound possesses a highly reactive polyunsaturated carbonyl moiety that is a substrate for Michael addition with thiol-containing biomolecules such as glutathione and cysteine residues on proteins. By reacting with glutathione and proteins, 15-d-PGJ2 is believed to exert potent biological activity. Despite the large number of publications that have ascribed bioactivity to this molecule, it is not known to what extent 15-d-PGJ2 is formed in vivo. Levels of free 15-d-PGJ2 measured in human biological fluids such as urine are low, and the biological importance of this compound has thus been questioned. Because of its reactivity, we hypothesized that 15-d-PGJ2 is present in vivo primarily as a Michael conjugate. Therefore, we undertook a detailed study of the metabolism of this compound in HepG2 cells that are known to metabolize other cyclopentenone eicosanoids. We report that HepG2 cells primarily convert 15-d-PGJ2 to a glutathione conjugate in which the carbonyl at C-11 is reduced to a hydroxyl. Subsequently, the glutathione portion of the molecule is hydrolyzed with loss of glutamic acid and glycine resulting in a cysteine conjugate. These findings confirm a general route for the metabolism of cyclopentenone eicosanoids in HepG2 cells and may pave the way for new insights regarding the formation of 15-d-PGJ2 in vivo.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Chromatography, High Pressure Liquid; Glutathione; Hepatocytes; Humans; Metabolic Detoxication, Phase II; Prostaglandin D2; Spectrometry, Mass, Electrospray Ionization

To investigate the effect of 15-deoxy-Delta(12,14)-prostaglandin J(2) (15-d-PGJ(2)) on the anoikis of hepatocellular carcinoma (HC) cells and mechanisms thereof.. Fibronectin or polyhydroxyethyl methacrylate (poly-HEMA) were coated onto tissue culture plates, cell growth status and morphological changes were detected by optical microscope. DNA fragmentation analysis and Flow cytometry were used to measure cell apoptotic activity. Western blotting analysis was performed to detect the levels of focal adhesion kinase (FAK) and phosphorylated FAK(p-FAK). Furthermore, small interfering RNA (siRNA) was used to suppress FAK expression.. The adhesion rate of the BEL-7402 cells treated with 15-d-PGJ(2) began to decrease 12 h after the treatment, time- and dose-dependently compared with the HC cell control group (all P < 0.05); when the concentration of 15-d-PGJ2 was 20 micromol/L, the adherent cells ratio at 24 h and 48 h later were (66.0 +/- 3.6)% and (35.0 +/- 5.0)% respectively. Anoikis of BEL-7402 cells was observed by flow cytometry and DNA fragmentation analysis. Western blotting showed that the p-FAK level of the BEL-7402 cells treated with 15-d-PGJ2 for 24 h decreased dose-dependently, however, the total FAK protein did not change.. 15-d-PGJ(2) induces anoikis and decreases the phosphorylated FAK expression of the hepatocellular carcinoma cells.

Topics: Anoikis; Apoptosis; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Dose-Response Relationship, Drug; Flow Cytometry; Focal Adhesion Protein-Tyrosine Kinases; Humans; Liver Neoplasms; Phosphorylation; Prostaglandin D2; RNA, Small Interfering; Transfection

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

Topics: Apoptosis; Apoptosis Regulatory Proteins; Blotting, Western; Carcinoma, Hepatocellular; Caspase 3; Caspases; Cell Survival; Dose-Response Relationship, Drug; Down-Regulation; Humans; Liver Neoplasms; Membrane Glycoproteins; NF-kappa B; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; TNF-Related Apoptosis-Inducing Ligand; Transcription Factors; Transfection; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

15-deoxy-delta12,14-prostaglandin J2 (15-d-PGJ2) induces apoptosis in several carcinoma cell lines and is a potent activator of peroxisome proliferators-activated receptor-gamma (PPAR-gamma). In the present study, we examined the effect of 15-d-PGJ2 on human hepatoma cells.. HuH-7 and HepG2 cell lines were used in all the experiments. The mRNA expression of PPAR-gamma was studied by reverse transcriptase-polymerase chain reaction. The cell viability was determined by a modified MTT assay. Two methods were used for the determination of apoptosis in hepatoma cells: the TUNEL assay, and detection of fragmented mono- and oligo-nucleosomes by ELISA.. The expression of PPAR-gamma mRNA and protein was detected in HuH-7 and HepG2. Treatment with 15-d-PGJ2 decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ2 induced apoptosis and this effect was time-dependent. Exposure of cells to 15-d-PGJ2 induced caspase-3 and -9 activation. Furthermore, co-treatment with the pan-caspase inhibitor Z-VAD-FMK or the caspase-3 inhibitor Z-DEVD-FMK blocked apoptosis of human hepatoma cells that had been treated with 15-d-PGJ2.. Our study demonstrates that PPAR-gamma is expressed in human hepatoma cell lines and that treatment with 15-d-PGJ2 inhibits the growth of these cells by inducing apoptosis through caspase activation.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Carcinoma, Hepatocellular; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Humans; Immunologic Factors; In Situ Nick-End Labeling; Liver Neoplasms; Oligopeptides; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; Transcription Factors