15-deoxy-delta(12-14)-prostaglandin-j2 and 2-4-thiazolidinedione

Cancer chemopreventive agents transcriptionally induce glutathione S-transferase (GST), which can protect cells from chemical-induced carcinogenesis. Activation of either NF-E2-related factor-2 (Nrf2) or the CCAAT/enhancer binding protein-beta (C/EBPbeta) contributes to GST induction. Peroxisome proliferator-activated receptor-gamma (PPARgamma) and the retinoic acid X receptor (RXR) play roles in regulating cell differentiation and chemoprevention. This study examined GSTA2 gene induction by the PPARgamma activator and 9-cis-retinoic acid (RA), a RXR ligand, and investigated the molecular basis of PPAR-RXR-mediated GSTA2 induction in the H4IIE hepatocytes. Either 15-deoxy-delta (12, 14)-prostaglandin J(2) (PGJ(2)) or RA induced GSTA2 with Nrf2 and C/EBPbeta activation. When compared with PGJ(2) or RA alone, PGJ(2) + RA enhanced GSTA2 induction, with increases in Nrf2 and C/EBPbeta activation. PGJ(2) + RA increased the luciferase reporter gene activity in the cells transfected with the -1.65-kb flanking region of the GSTA2 gene. Thiazolidinedione PPARgamma agonists, troglitazone, rosiglitazone, and pioglitazone, in combination with RA, potentiated GSTA2 induction, confirming that the activation of the PPARgamma and RXR heterodimer contributed to GSTA2 expression. Deletion of the antioxidant response element- or C/EBP-binding sites or the overexpression of dominant-negative mutant of C/EBP abolished the reporter gene expression. PGJ2 + RA increased the binding of the PPARgamma - RXR heterodimer to the putative PPAR-response elements (PPREs) in the GSTA2 promoter. Specific mutations of these multiple PPRE sites resulted in the complete loss of its responsiveness to PGJ2 + RA, which suggests that these binding sites function as a PPRE-responsive enhancer module (PPREM). Transactivation of PPREM by the PPARgamma - RXR heterodimer was verified by the effective GSTA2 induction in the cells treated with PGJ2 + RA after transfecting them with the plasmids encoding PPARgamma1 and RXRalpha. In conclusion, the PPARgamma - RXR heterodimer promotes GSTA2 induction by activating PPREM in the GSTA2 gene, as well as inducing Nrf2 and C/EBPbeta activation.

Topics: Alitretinoin; Animals; Base Sequence; CCAAT-Enhancer-Binding Protein-beta; Cell Line; DNA-Binding Proteins; Gene Expression Regulation, Enzymologic; Glutathione Transferase; Hepatocytes; Mice; Molecular Sequence Data; NF-E2-Related Factor 2; Promoter Regions, Genetic; Prostaglandin D2; Rats; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Response Elements; Retinoid X Receptors; Thiazolidinediones; Trans-Activators; Transcription Factors; Transcriptional Activation; Tretinoin

The synthetic thiazolidinedione ligands of peroxisome proliferator-activated receptor-gamma (PPARgamma) improve insulin sensitivity in type II diabetes and induce GLUT4 mRNA expression in fat and muscle. However, the molecular mechanisms involved are still unclear. We studied the regulatory effects of PPARgamma and its ligands on GLUT4 gene expression in primary rat adipocytes and CHO-K1 cells cotransfected with PPARgamma and the GLUT4 promoter reporter. PPARgamma1 and PPARgamma2 repressed the activity of the GLUT4 promoter in a dose-dependent manner. Whereas this repression was augmented by the natural ligand 15Delta-prostaglandin J2, it was completely alleviated by rosiglitazone (Rg). Ligand binding-defective mutants PPARgamma1-L468A/E471A and PPARgamma2-L496A/E499A retained the repression effect, which was unaffected by Rg, whereas the PPARgamma2-S112A mutant exhibited a 50% reduced capacity to repress GLUT4 promoter activity. The -66/+163 bp GLUT4 promoter region was sufficient to mediate PPARgamma inhibitory effects. The PPARgamma/retinoid X receptor-alpha heterodimer directly bound to this region, whereas binding was abolished in the presence of Rg. Thus, we show that PPARgamma represses transcriptional activity of the GLUT4 promoter via direct and specific binding of PPARgamma/retinoid X receptor-alpha to the GLUT4 promoter. This effect requires an intact Ser112 phosphorylation site on PPARgamma and is completely alleviated by Rg, acting via its ligand-binding domain. These data suggest a novel mechanism by which Rg exerts its antidiabetic effects via detaching PPARgamma from the GLUT4 gene promoter, thus leading to increased GLUT4 expression and enhanced insulin sensitivity.

Topics: Adipocytes; Animals; CHO Cells; Cricetinae; Dimerization; Fibroblasts; Gene Expression Regulation; Genetic Complementation Test; Glucose Transporter Type 4; Humans; Hypoglycemic Agents; Immunologic Factors; Mice; Monosaccharide Transport Proteins; Muscle Proteins; Promoter Regions, Genetic; Prostaglandin D2; Protein Structure, Tertiary; Rats; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Retinoid X Receptors; Rosiglitazone; Suppression, Genetic; Thiazoles; Thiazolidinediones; Transcription Factors; Transcription, Genetic

Activation of peroxisome proliferator-activated receptor gamma (PPARgamma) has been linked to induction of differentiation, cell growth inhibition and apoptosis in several types of human cancer. However, the possible effects of PPARgamma agonists on human oral squamous cell carcinoma have not yet been reported. In this study, treatment with 15-deoxy-Delta(12,14)-PGJ(2) (15-PGJ(2)), a natural PPARgamma ligand, induced a significant reduction of oral squamous cell carcinoma cell growth, which was mainly attributed to upregulation of apoptosis. Interestingly, rosiglitazone and ciglitazone, two members of the thiazolidinedione family of PPARgamma activators, did not exert a growth inhibitory effect. Given the critical role that the oncogene signal transducer and activator of transcription 3 (Stat3) plays in head and neck carcinogenesis, its potential regulation by PPARgamma ligands was also examined. Treatment of oral squamous cell carcinoma cells with 15-PGJ(2) induced an initial reduction and eventual elimination of both phosphorylated and unphosphorylated Stat3 protein levels. In contrast, other PPARgamma did not induce similar effects. Our results provide the first evidence of significant antineoplastic effects of 15-PGJ(2) on human oral squamous cell carcinoma cells, which may be related to downmodulation of Stat3 and are at least partly mediated through PPARgamma-independent events.

Topics: Apoptosis; Blotting, Western; Carcinoma, Squamous Cell; Cell Cycle; Cell Division; DNA Primers; DNA-Binding Proteins; Down-Regulation; Humans; Immunoenzyme Techniques; Immunologic Factors; Mouth Neoplasms; Phosphorylation; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; STAT3 Transcription Factor; Thiazoles; Thiazolidinediones; Trans-Activators; Transcription Factors; Tumor Cells, Cultured

Proliferation of intrinsic glomerular cells is a common response to renal injury. Acutely, proliferation may be beneficial, but sustained glomerular hypercellularity after injury is associated with progressive renal failure. To identify endogenous factors that may be responsible for regulating glomerular cell number, the effects of J-series cyclopentenone prostaglandins (PGs) on human glomerular mesangial cell proliferation and death were examined.. Human mesangial cells were grown in the presence or absence of PGJ2 or its metabolite 15-Deoxy-Delta12,14-PGJ2 (15dPGJ2). The number of viable cells was measured by the reduction of the tetrazolium MTS to a colored formazan product. Apoptosis was assessed by caspase-3 activation and DNA fragmentation.. PGJ2 at concentrations up to 10 micromol/L caused mesangial proliferation. 15dPGJ2 also caused mesangial proliferation at low concentrations (< or =2.5 micromol/L), but induced mesangial cell death at higher concentrations (>5 micromol/L). Cell death occurred in part through apoptosis, measured as an increase in caspase-3 activity and DNA fragmentation in 15dPGJ2-treated cells. Cell death was associated with a decline in baseline phosphorylation of the survival factor Akt and increased Akt degradation, whereas 15dPGJ2-induced mesangial proliferation was blocked by inhibition of the PI 3-kinase/Akt pathway. 15dPGJ2 is a potent PPARgamma agonist. Like 15dPGJ2, treatment of mesangial cells with thiazolidinedione-type PPARgamma ligands (10 to 20 micromol/L) caused significant cell death, but at lower concentrations also caused a small degree of proliferation.. J-series prostaglandins thus may be involved in the initiation of glomerular hypercellularity through Akt-dependent proliferation, and restoration of normal glomerular architecture through PPARgamma-mediated apoptosis. Manipulation of these prostaglandins may be relevant to the treatment of progressive glomerular disease.

Topics: 1-Phosphatidylinositol 4-Kinase; Cell Death; Cell Division; Cells, Cultured; Chromans; Chromones; Enzyme Inhibitors; Glomerular Mesangium; Humans; Morpholines; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Thiazoles; Thiazolidinediones; Transcription Factors; Troglitazone

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-activated transcriptional factor belonging to the steroid receptor superfamily. It plays a role in both adipocyte differentiation and tumorgenesis. Up-date, the up-regulation of PPAR-gamma expression is a frequent occurrence in a variety of different malignant tumors. In this study, we investigated the expression of PPAR-gamma in human renal cell carcinoma (RCC) tissues, and the role of PPAR-gamma in cell growth in human RCC-derived cell lines. Immunohistochemistry showed a strong immunoreactive expression of PPAR-gamma in all slides from cancer specimens. RT-PCR and Western blot analysis showed 3 RCC cell lines expressed PPAR-gamma mRNA and its protein. MTT assay in 3 RCC cells showed that the synthetic PPAR-gamma agonists thiazolidinedione compounds (pioglitazone and troglitazone) and the endogeneous PPAR-gamma ligand, 15-deoxy-Delta12,14-prostaglandin J(2) (15dPGJ(2)) inhibited the growth of the RCC cells. These results suggest that PPAR-gamma may become a new target in the treatment of RCC.

Topics: Antineoplastic Agents; Blotting, Western; Carcinoma, Renal Cell; Cell Division; Chromans; Coloring Agents; Dose-Response Relationship, Drug; Humans; Hypoglycemic Agents; Immunohistochemistry; Immunologic Factors; Kidney Neoplasms; Ligands; Pioglitazone; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tetrazolium Salts; Thiazoles; Thiazolidinediones; Transcription Factors; Troglitazone; Tumor Cells, Cultured; Up-Regulation

Release of arachidonic acid from rat liver cells is stimulated after a 6-hour incubation with 9-cis retinoic acid, all trans retinoic acid, the selective peroxisome proliferator-activated receptor-gamma synthetic thiazolidinedione, ciglitazone, the cyclopentenones, 15-deoxy-Delta(12,14) PGJ2 and PGA1 and the non-steroidal anti-inflammatory drugs, celecoxib and indomethacin. The rates of the release stimulated by 15-deoxy-Delta(12,14) PGJ2 differ from those observed with celecoxib. Arachidonic acid release by9-cis retinoic acid in the presence of either ciglitazone or trans retinoic acid is synergistic. It is additive in the presence of celecoxib. Cycloheximide and actinomycin inhibit the release of arachidonic acid stimulated by 15-deoxy-Delta(12,14) PGJ2 but not by celecoxib. The findings indicate that agonists of the peroxisome proliferator-activated receptor-gamma and retinoic acid receptors stimulate the release of arachidonic acid. The mechanisms involved may differ in the cases of 15-deoxy-Delta(12,14) PGJ2 and celecoxib.

Topics: Alitretinoin; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acid; Celecoxib; Cell Line; Cycloheximide; Dactinomycin; Dose-Response Relationship, Drug; Drug Synergism; Indomethacin; Kinetics; Liver; Prostaglandin D2; Prostaglandins A; Pyrazoles; Rats; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Sulfonamides; Thiazoles; Thiazolidinediones; Transcription Factors; Tretinoin

The purpose of this study was to determine the effect of the peroxisome proliferator-activated receptor gamma-(PPAR gamma) ligands troglitazone (TRO), rosiglitazone (RSG), and 15-deoxy-delta prostaglandin J2 (15d-PGJ2) on vascular smooth muscle cell (VSMC) migration directed by multiple chemoattractants. Involvement of mitogen-activated protein kinase (MAPK) in migration also was examined, because TRO was previously shown to inhibit nuclear events stimulated by this pathway during mitogenic signaling in VSMCs. Migration of rat aortic VSMCs was induced 5.4-fold by PDGF, 4.6-fold by thrombin, and 2.3-fold by insulin-like growth factor I (IGF-I; all values of p < 0.05). The PPAR gamma ligands 15d-PGJ2, RSG, or TRO all inhibited VSMC migration with the following order of potency: 15d-PGJ2 > RSG > TRO. Inhibition of MAPK signaling with PD98059 completely blocked PDGF-, thrombin-, and IGF-I-induced migration. All chemoattractants induced MAPK activation. PPAR gamma ligands did not inhibit MAPK activation, suggesting a nuclear effect of these ligands downstream of MAPK. The importance of nuclear events was confirmed because actinomycin D also blocked migration. We conclude that PPAR gamma ligands are potent inhibitors of VSMC migration pathways, dependent on MAPK and nuclear events. PPAR gamma ligands act downstream of the cytoplasmic activation of MAPK and appear to exert their effects in the nucleus. Because VSMC migration plays an important role in the formation of atherosclerotic lesions and restenosis, PPAR gamma ligands like TRO and RSG, which ameliorate insulin resistance in humans, also may protect the vasculature from diabetes-enhanced injury.

Topics: Animals; Aorta, Thoracic; Calcium-Calmodulin-Dependent Protein Kinases; Cell Movement; Cells, Cultured; Chemotactic Factors; Chromans; Cycloheximide; Dactinomycin; Enzyme Activation; Insulin-Like Growth Factor I; Ligands; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Prostaglandin D2; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Rosiglitazone; Thiazoles; Thiazolidinediones; Thrombin; Transcription Factors; Troglitazone

To investigate the role of peroxisome proliferator-activated receptor gamma (PPARgamma) in adipocyte formation within the skeletal muscle of beef cattle, fibroblast-like cells were isolated from the longissimus muscle of cattle and cultured with activators of murine PPARgammaA thiazolidinedione T-174, which is a specific ligand for PPARgamma, stimulated adipose differentiation (evaluated by counting differentiated adipocytes under microscopic observation) in a dose-dependent fashion. A peroxisome proliferator Wy14,643 which strongly activates the alpha isoform of murine PPAR also stimulated differentiation but its potency was weaker than that of T-174. Unexpectedly, 15-deoxy-Delta12,14-prostaglandin J2, which is believed to be an endogenous ligand for PPARgamma, could not induce adipose differentiation in doses which have been found to be effective on rodent cells. Immunoblotting analysis confirmed the significant expression of PPARgamma protein in fibroblast-like cell cultures prepared from bovine skeletal muscle. In conclusion, bovine skeletal muscle contains adipose precursor cells expressing functionally active PPARgamma.

Topics: Adipocytes; Adipose Tissue; Animals; Cattle; Cell Differentiation; Cells, Cultured; Fibroblasts; Ligands; Male; Muscle, Skeletal; Nuclear Proteins; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Thiazoles; Thiazolidinediones; Transcription Factors