prostaglandin-d2 and Stomach-Neoplasms

The antitumor effect of prostaglandin D2 (PGD2) on gastric cancer (GC) has been known for decades. However, the mechanism of PGD2's control of GC growth is unclear. Cancer stem cells (CSCs) are implicated in tumor neovascularization, invasiveness, and therapeutic resistance. Herein, we discovered that signaling between PGD2 and its receptor (PTGDR2) has the ability to restrict the self-renewal of GC cells in vitro and suppress tumor growth and metastasis in vivo. To obtain these findings, we first determined that PGD2 synthase (L-PTGDS) and PTGDR2 expression were lower in GC tissues than adjacent tissues and was associated with the patients' prognosis. Moreover, the expression of L-PTGDS and PTGDR2 was negatively correlated with the GC-CSC markers Sall4 and Lgr5 in GC tissues. Second, L-PTGDS and PTGDR2 expression were knocked down in CSC-like cells, resulting in enhanced expression of CSC markers and self-renewal ability. Direct PGD2 stimulation and L-PTGDS overexpression produced the opposite effect. Thirdly, PGD2 inhibited tumor growth and incidence rate in a subcutaneous tumor model and suppressed liver and mesenteric metastasis in a peritoneal metastasis model. Interfering with the expression of PTGDR2 reversed these effects in vivo. Last, a mechanistic study found that PGD2 inhibited STAT3 phosphorylation and nuclear expression. Further experiments revealed that the inhibitory effect of PGD2 on the expression of CSC markers disappeared after mutations were introduced into STAT3 phosphorylation (Thr705) site. In short, this study reveals a novel function of PGD2/PTGDR2 signaling on CSC regulation and provides a new way to control the development of GC. Stem Cells 2018;36:990-1003.

Topics: Animals; Carcinogenesis; Humans; Immunohistochemistry; Mice; Neoplastic Stem Cells; Prostaglandin D2; Signal Transduction; Stomach Neoplasms; Transfection

The antitumor activity of prostaglandin (PG) D2 has been demonstrated against some types of cancer, including gastric cancer. However, exogenous PGD2 is not useful from a clinical point of view because it is rapidly metabolized in vivo. The aim of this study was to clarify the antitumor efficacy of an alternative, PGD synthase (PGDS), on gastric cancer cells. The effects of PGD2 and PGDS on the proliferation of gastric cancer cells were examined in vivo and in vitro. The expression levels of PGD2 receptors and peroxisome proliferator-activated receptor γ (PPARγ) were evaluated by RT-PCR. The effects of a PPARγ antagonist or siPPARγ on the proliferation of cancer cells and the c-myc and cyclin D1 expression were examined in the presence or absence of PGD2 or PGDS. PPARγ was expressed in gastric cancer cell lines, but PGD2 receptors were not. PGD2 and PGDS significantly decreased the proliferation of gastric cancer cells that highly expressed PPARγ. PGDS increased the PGD2 production of gastric cancer cells. A PPARγ antagonist and siPPARγ transfection significantly suppressed the growth-inhibitory effects of PGD2 and PGDS. Expression of c-myc and cyclin D1 was significantly decreased by PGD2 ; this inhibitory effect was suppressed by PPARγ antagonist. Both PGD2 and PGDS significantly decreased subcutaneous tumor growth in vivo. Tumor volume after PGDS treatment was significantly less than PGD2 treatment. These findings suggest that PGDS and PGD2 decrease the proliferation of gastric cancer cells through PPARγ signaling. PGDS is a potentially promising therapeutic agent for gastric cancers that express PPARγ.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Humans; Intramolecular Oxidoreductases; Lipocalins; Mice; PPAR gamma; Prostaglandin D2; Receptors, Immunologic; Receptors, Prostaglandin; Signal Transduction; Stomach Neoplasms; Xenograft Model Antitumor Assays

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

Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have been shown to inhibit angiogenesis. We showed that treatment with 15d-PGJ(2), a PPARgamma ligand, downregulate the expressions of angiopoietin-1 (Ang-1) in gastric cancer cells MKN45. The medium of MKN45 cells treated with 15d-PGJ(2) significantly inhibited the migration and tube formation of human umbilical vein endothelial cells (HUVECs). Moreover, Matrigel plug assay revealed that 15d-PGJ(2) reduced in vivo angiogenesis induced by MKN45 cells. These modulations were restored by the addition of recombinant Ang-1. Our findings supported that 15d-PGJ(2) suppressed angiogenesis of gastric cancer cells by downregulation of Ang-1.

Topics: Angiogenesis Inhibitors; Angiopoietin-1; Animals; Cell Line; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Down-Regulation; Endothelial Cells; Female; Gene Expression Profiling; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neovascularization, Pathologic; Neovascularization, Physiologic; Oligonucleotide Array Sequence Analysis; Prostaglandin D2; Stomach Neoplasms; Vascular Endothelial Growth Factor A

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

To investigate the influence of peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, 15-deoxy-12, 14-prostaglandin J2 (15dPGJ2) on the proliferation and apoptosis of MCG-803 human gastric cancer cell lines.. Cell proliferation was measured by 3H-TdR assay. Apoptosis was determined by ELISA and TUNEL staining. Protein and mRNA level of bcl-2 family and COXs were measured by Western blotting and Northern blotting respectively. PGE2 production was examined by RIA.. 15dPGJ2 inhibited cell growth and induced apoptosis of MCG-803 cells. The COX-2 and bcl-2/bax ratios were decreased following 15dPGJ2 treatment. The PGE2 production in supernatants was also decreased. These changes were in a dose-dependent manner.. 15dPGJ2 may be a useful therapeutic agent for the treatment of gastric cancer.

Topics: Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; Cell Division; Cell Line, Tumor; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Gene Expression Regulation, Neoplastic; Humans; Isoenzymes; Membrane Proteins; Prostaglandin D2; Prostaglandin-Endoperoxide Synthases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Stomach Neoplasms; Transcription Factors

Eicosanoids have the ability to stimulate or inhibit the proliferation of epithelial cells, and they have been shown to modulate the growth characteristics of certain tumor cell lines. In addition, many epithelial cells have the ability to produce eicosanoids, which may then serve as autocrine growth factors. We have measured the eicosanoids produced by the human stomach cell line AGS using reverse-phase high-performance liquid chromatography. AGS cells were incubated with [3H]arachidonic acid and stimulated to release eicosanoids by the calcium ionophore A23187. Unlike its counterpart from the normal stomach, the AGS tumor cell line produced prominent amounts of the leukotrienes D4, C4, and B4; 6-keto-prostaglandin F1 alpha; thromboxane B2; hydroxyeicosatetraenoic acids; and smaller amounts of other prostaglandins in response to A23187. Under basal condition (in the absence of calcium ionophore), hydroxyeicosatetraenoic acid was produced in greatest relative amount compared with the other eicosanoids. To elucidate the potential autacoid role of these agents, exogenous eicosanoids were added to AGS cells, and proliferation was measured. Prostaglandins D2 and E2 suppressed the growth of AGS cells in a dose-dependent manner. On the other hand, leukotrienes D4 and C4 had a dose-dependent proliferative effect on cell growth. The lipoxygenase inhibitor nordihydroguaiaretic acid (10(-6), 10(-5) M) and hydrocortisone (10(-5) M) had dose-dependent suppressive effects on growth, whereas indomethacin (10(-6) M and 10(-5) M) had no effect. These results suggest that AGS cells preferentially metabolize arachidonic acid through the 5-lipoxygenase pathway, which results in the production of growth-stimulatory autocoids. Agents that selectively block this arm of eicosanoid metabolism might be useful therapeutic agents in the treatment of certain gastrointestinal cancers.

Topics: Arachidonic Acid; Bromodeoxyuridine; Cell Division; Chromatography, High Pressure Liquid; Dinoprostone; DNA Replication; Dose-Response Relationship, Drug; Eicosanoids; Humans; Hydrocortisone; Masoprocol; Mitotic Index; Prostaglandin D2; SRS-A; Stomach Neoplasms; Thymidine; Tritium; Tumor Cells, Cultured