15-deoxy-delta(12-14)-prostaglandin-j2 and Stomach-Neoplasms

To investigate whether peroxisome proliferator-activated receptor gamma (PPAR-gamma) is expressed in human gastric carcinoma and whether PPAR-gamma is a potential target for gastric carcinoma therapy.. PPAR-gamma protein in gastric carcinoma was examined by immunohistochemistry. In the gastric carcinoma cell line MGC803, PPAR-gamma, survivin, Skp2 and p27 protein and mRNA were examined by Western blotting and real-time reverse transcription-polymerase chain reaction, respectively; proliferation was examined by MTT; apoptosis was examined by chromatin staining with Hoechst 33342 and fluorescence activated cell sorting (FACS). and cell cycle was examined by FACS; the knockdown of PPAR-gamma was done by RNA interference.. A high level of expression of PPAR-gamma was observed in human gastric carcinoma and in a human gastric carcinoma cell line MGC803. The PPAR-gamma agonist 15-deoxy-Delta12,14-prostaglandin J(2) (15d-PGJ(2)) inhibited growth, and induced apoptosis and G(1)/G(0) cell cycle arrest in MGC803 cells in a concentration-dependent and time-dependent manner. The effect of 15d-PGJ(2) on MGC803 cells was not reversed by the selective and irreversible antagonist GW9662 for PPAR-gamma. Furthermore, survivin and Skp2 expression were decreased, whereas p27 expression was enhanced following 15d-PGJ(2) treatment in a dose-dependent manner in MGC803 cells. Interestingly, we also found that small interfering RNA for PPAR-gamma inhibited growth and induced apoptosis in MGC803 cells. The inhibition of PPAR-gamma function may be a potentially important and novel modality for treatment and prevention of gastric carcinoma.. A PPAR-gamma agonist inhibited growth of human gastric carcinoma MGC803 cells by inducing apoptosis and G(1)/G(0) cell cycle arrest with the involvement of survivin, Skp2 and p27 and not via PPAR-gamma.

Topics: Adult; Aged; Animals; Apoptosis; Cell Cycle; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p27; Female; Humans; Inhibitor of Apoptosis Proteins; Male; Microtubule-Associated Proteins; Middle Aged; PPAR gamma; Prostaglandin D2; RNA, Small Interfering; S-Phase Kinase-Associated Proteins; Stomach Neoplasms; Survivin

Helicobacter pylori deregulates the genes that control homeostasis between apoptosis and cell proliferation of gastric epithelial cells. Nuclear factor-kappaB (NF-kappaB) has an important role in H. pylori-induced apoptosis in gastric epithelial cells. The peroxisome proliferator-activated receptor-gamma ligand 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) regulates growth and the signaling cascade in H. pylori-infected gastric epithelial cells. In the present study, we determined whether 15d-PGJ(2) inhibits apoptosis by regulating apoptotic gene expression and NF-kappaB activation in gastric epithelial cells infected with CagA+, VacA+H. pylori in a Korean isolate (HP99). 15d-PGJ(2) was found to inhibit H. pylori-induced DNA fragmentation and cell death. 15d-PGJ(2) induced downregulation of proapoptotic Bax and upregulation of antiapoptotic Bcl-2 as well as suppression of NF-kappaB activation caused by H. pylori in gastric epithelial cells. The results suggest that 15d-PGJ(2) inhibits apoptotic cell death by inhibiting NF-kappaB activation and apoptotic gene expression in gastric epithelial cells.

Topics: Adenocarcinoma; Antigens, Bacterial; Apoptosis; Bacterial Proteins; bcl-2-Associated X Protein; Blotting, Western; Cell Line, Tumor; DNA Fragmentation; Electrophoretic Mobility Shift Assay; Enzyme-Linked Immunosorbent Assay; Helicobacter pylori; Humans; NF-kappa B; Oligonucleotides; Prostaglandin D2; Protein Binding; Proto-Oncogene Proteins c-bcl-2; Stomach Neoplasms

Although peroxisome proliferator activated receptor gamma (PPARgamma) agonists have been implicated in differentiation and growth inhibition of cancer cells, the potential therapeutic and chemopreventive effects on gastric cancer are poorly defined. We examined the in vitro and in vivo effects of PPARgamma ligands on growth of gastric cancer, and the effect of PPARgamma activation on expression of cyclooxygenase 2 (COX-2) and cancer related genes.. Gastric cell lines (MKN28 and MKN45) were treated with two specific PPARgamma ligands: ciglitazone and 15-deoxy-Delta(12,)(14)-prostaglandin J(2). Cell growth was determined by bromodeoxyuridine incorporation assay and apoptosis was measured by DNA fragmentation. Expression of COX-2 was determined by western blot and real time quantitative polymerase chain reaction (PCR). Expression profiles of cancer related genes were screened with cDNA array. In vivo growth of implanted MKN45 cells in nude mice was monitored after oral treatment with rosiglitazone.. PPARgamma ligands suppressed the in vitro growth of MKN45 cells in a dose dependent manner whereas prostacyclin, a PPARdelta agonist, had no growth inhibitory effect. Growth inhibition was more pronounced in MKN45 cells, which was accompanied by DNA fragmentation and downregulation of COX-2. Screening by cDNA microarray showed that PPARgamma ligand treatment was associated with upregulation of bad and p53, and downregulation of bcl-2, bcl-xl, and cyclin E1 in MKN45 cells, which was confirmed by quantitative real time PCR. In contrast, MKN28 cells with lower PPARgamma and COX-2 expression levels had lower growth inhibitory responses to PPARgamma ligands. Microarray experiments only showed induction of the bad gene in MKN28 cells. In vivo growth of MKN45 cells in nude mice was retarded by rosiglitazone. Mean tumour volume in rosiglitazone treated mice was significantly lower than controls at six weeks (p = 0.019) and seven weeks (p = 0.001) after treatment.. PPARgamma ligands suppress both in vitro and in vivo growth of gastric cancer and may play a major role in cancer therapy and prevention.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Division; Cyclooxygenase 2; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Isoenzymes; Ligands; Male; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Proteins; Neoplasm Transplantation; Nuclear Receptor Coactivators; Prostaglandin D2; Prostaglandin-Endoperoxide Synthases; Rosiglitazone; Stomach Neoplasms; Thiazolidinediones; Transcription Factors; Tumor Cells, Cultured

Cyclopentenone prostaglandins (CyPGs), derivatives of arachidonic acid, have been suggested to exert growth-inhibitory activity through peroxisome proliferator-activated receptor (PPAR)-dependent and -independent mechanisms. Here we examined various eicosanoids for growth inhibition and found that the terminal derivative of prostaglandin (PG) J(2) metabolism, 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), and PGA(1) markedly inhibited the growth and induced apoptosis in AGS gastric carcinoma cells. There were no significant increases in cell death and DNA-fragmentation in the cells with overexpression of PPARalpha or PPARgamma, indicating the possibility that 15d-PGJ(2) and PGA(1) induced apoptosis through PPAR-independent pathway. Moreover, 15d-PGJ(2) and PGA(1) activated the c-jun N-terminal kinase (JNK) and caspase-3 activity in dose- and time-dependent manners. To examine further the role of JNK signaling cascades in apoptosis induced by 15d-PGJ(2) and PGA(1), we transfected dominant-negative (DN) mutants of JNK plasmid into the cells to analyze the apoptotic characteristics of cells overexpressing DN-JNK following exposure to 15d-PGJ(2) and PGA(1). Overexpression of DN-JNK significantly repressed both endogenous JNK and caspase-3 activity, and subsequently decreased apoptosis induced by 15d-PGJ(2) and PGA(1). These results suggested that CyPGs, such as 15d-PGJ(2) and PGA(1), activated JNK signaling pathway, and that JNK activation may be involved in 15d-PGJ(2)- and PGA(1)-induced apoptosis.

Topics: Apoptosis; Caspase 3; Caspases; Cell Division; Enzyme Activation; Humans; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Mutation; Prostaglandin D2; Prostaglandins A; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Stomach Neoplasms; Transcription Factors; Transfection; Tumor Cells, Cultured