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

There is growing evidence that stress-coping mechanisms represent tumor cell vulnerabilities that may function as therapeutically beneficial targets. Recent work has delineated an integrated stress adaptation mechanism that is characterized by the formation of cytoplasmic mRNA and protein foci, termed stress granules (SGs). Here, we demonstrate that SGs are markedly elevated in mutant KRAS cells following exposure to stress-inducing stimuli. The upregulation of SGs by mutant KRAS is dependent on the production of the signaling lipid molecule 15-deoxy-delta 12,14 prostaglandin J2 (15-d-PGJ2) and confers cytoprotection against stress stimuli and chemotherapeutic agents. The secretion of 15-d-PGJ2 by mutant KRAS cells is sufficient to enhance SG formation and stress resistance in cancer cells that are wild-type for KRAS. Our findings identify a mutant KRAS-dependent cell non-autonomous mechanism that may afford the establishment of a stress-resistant niche that encompasses different tumor subclones. These results should inform the design of strategies to eradicate tumor cell communities.

Topics: Adenocarcinoma; Animals; Cell Line, Tumor; Colonic Neoplasms; Cytoplasmic Granules; Drug Resistance, Neoplasm; Eukaryotic Initiation Factor-4A; Female; Heterografts; Humans; Mice; Mutation; Neoplasm Transplantation; Pancreatic Neoplasms; Prostaglandin D2; Proto-Oncogene Proteins p21(ras); Up-Regulation

The nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR)-gamma plays a role in cancer development in addition to its role in glucose metabolism. The natural ligand of PPAR-gamma, namely, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), has been shown to possess antineoplastic activity in cancer cells. However, the mechanism underlying its antineoplastic activity remains to be elucidated. Inhibition of the expression of human telomerase reverse transcriptase (hTERT), a major determinant of telomerase activity, reportedly induces rapid apoptosis in cancer cells. In this study, we investigated the effect of 15d-PGJ(2) on hTERT expression. We found that 15d-PGJ(2) induced apoptosis in the MIAPaCa-2 pancreatic cancer cells and dose-dependently decreased hTERT mRNA and protein expression. Down-regulation of hTERT expression by hTERT-specific small inhibitory RNA also induced apoptosis. Furthermore, 15d-PGJ(2) attenuated the DNA binding of estrogen receptor (ER). MIAPaCa-2 expressed only ERbeta, and although its expression did not decrease due to 15d-PGJ(2), its phosphorylation was suppressed. Additionally, a mitogen-activated protein kinase (MAPK) kinase inhibitor decreased ERbeta phosphorylation, and 15d-PGJ(2) attenuated MAPK activity. We conclude that hTERT down-regulation by 15d-PGJ(2) plays an important role in the proapoptotic property of the latter. Furthermore, 15d-PGJ(2) inhibits ERbeta-mediated hTERT gene transcription by suppressing ERbeta phosphorylation via the inhibition of MAP kinase signaling.

Topics: Apoptosis; Cell Line, Tumor; DNA, Neoplasm; Down-Regulation; Estrogen Receptor beta; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Signaling System; Pancreatic Neoplasms; Phosphoprotein Phosphatases; Phosphorylation; Phosphoserine; Promoter Regions, Genetic; Prostaglandin D2; Protein Binding; RNA, Small Interfering; Telomerase; Transcription, Genetic

Cancer cell invasion and metastasis require the concerted action of several proteases that degrade extracellular matrix proteins and basement membranes. Recent reports suggest the plasminogen activator system plays a critical role in pancreatic cancer biology. In the present study, we determined the contribution of the plasminogen activator system to pancreatic cancer cell invasion in vitro. Moreover, the effect of peroxisome proliferator-activated receptor (PPAR)-gamma ligands, which are currently in clinical use as antidiabetic drugs and interestingly seem to display antitumor activities, on pancreatic cancer cell invasion and the plasminogen activator system was assessed. Expression of components of the plasminogen activator system [i.e., urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1, and uPA receptor] was detected in six human pancreatic cancer cell lines. Inhibition of urokinase activity by specific synthetic compounds reduced baseline pancreatic cancer cell invasion. The PPAR-gamma ligands 15-deoxy-Delta12,14-prostaglandin J2 and ciglitazone also attenuated pancreatic cancer cell invasion. This effect was abrogated by dominant-negative PPAR-gamma receptors and pharmacologic PPAR-gamma inhibitors. Moreover, activation of PPAR-gamma by ligands increased plasminogen activator inhibitor-1 and decreased uPA levels in pancreatic cancer cells, and this was accompanied by a reduction in total urokinase activity. The present study shows that the plasminogen activator system plays an integral role in pancreatic cancer cell invasion in vitro. Activation of the nuclear receptor PPAR-gamma by ligands reduced pancreatic cancer cell invasion, which was largely mediated by modulation of the plasminogen activator system. These findings further underscore the potential role of PPAR-gamma ligands as therapeutic agents in pancreatic cancer.

Topics: Cell Line, Tumor; Down-Regulation; Humans; Ligands; Neoplasm Invasiveness; Pancreatic Neoplasms; Plasminogen Activator Inhibitor 1; PPAR gamma; Prostaglandin D2; Thiazolidinediones; Up-Regulation; Urokinase-Type Plasminogen Activator

We have previously reported that 15-deoxy-delta-prostaglandin J2 (15d-PGJ2), a potent ligand for peroxisome proliferator-activated receptor gamma (PPARgamma), induces caspase-mediated apoptosis in human pancreatic cancer cell lines. Mitogen-activated protein kinases (MAPKs) are known to regulate apoptosis in various cancers. The purpose of this study was to investigate the role of MAPKs (ERK, JNK, and p38) in 15d-PGJ2-induced pancreatic cancer cell apoptosis.. The effect of 15d-PGJ2 on MAPK activity was investigated by kinase assays using the human pancreatic cancer cell line MIA PaCa-2. Western blot analysis was performed to analyze phosphorylation of MAPKs, activation of caspases and poly ADP-ribose polymerase (PARP) cleavage. Apoptosis was evaluated by caspase-3 enzymatic activity and DNA fragmentation assay.. 15d-PGJ2 activated all 3 MAPKs in a dose- and time-dependent fashion. SB202190, an inhibitor of p38, prevented 15d-PGJ2-induced activation of caspase-8, -9, and -3 and significantly decreased apoptosis. This effect was potentiated by SP600125, an inhibitor of JNK, although SP600125 alone had no significant effect on 15d-PGJ2-induced apoptosis. In contrast, PD98059, an inhibitor of MEK, significantly increased sensitivity to 15d-PGJ2-induced apoptosis.. 15d-PGJ2 stimulates proapoptotic and antiapoptotic MAPK pathways. Sensitivity to 15d-PGJ2-induced apoptosis is increased by ERK inhibition but decreased by inhibition of p38.

Topics: Antineoplastic Agents; Apoptosis; Caspases; Cell Line, Tumor; Enzyme Activation; Humans; Ligands; Mitogen-Activated Protein Kinases; Pancreatic Neoplasms; PPAR gamma; Prostaglandin D2

Peroxisome proliferator-activated receptor gamma (PPARgamma) is expressed in certain human cancers; ligand-induced PPARgamma activation can result in growth inhibition and differentiation in these cells. However, the precise mechanism for the antiproliferative effect of PPARgamma ligands is not entirely known.. The purpose of this study was to examine the effect of PPARgamma ligands on pancreatic cancer cell growth and invasiveness.. The effect of two PPARgamma ligands, 15 deoxy-delta12,14 prostaglandin J2 (15d-PGJ2) and ciglitazone, on the growth of four human pancreatic cancer cell lines (BxPC-3, MIA PaCa-2, Panc-1, and L3.6) was assessed. Expression of cell-cycle and apoptotic-related proteins was measured. Finally, the effect of 15d-PGJ2 on pancreatic cancer cell invasiveness and matrix metalloproteinase expression was determined.. Both 15d-PGJ2 and ciglitazone inhibited the growth of all four pancreatic cancer cell lines in a dose- and time-dependent fashion. Treatment of BxPC-3 cells with 15d-PGJ2 resulted in a time-dependent decrease in cyclin D1 expression associated with a concomitant induction of p21waf1 and p27kip1. In addition, 15d-PGJ2 treatment induced apoptosis through activation of caspase-8, -9, and -3. Moreover, pancreatic cancer cell invasiveness was significantly suppressed after treatment with a nontoxic dose of 15d-PGJ2, which was associated with a reduction of MMP-2 and MMP-9 protein levels and activity.. These results demonstrate that PPARgamma ligands have the dual advantage of inhibiting pancreatic cancer cell growth while reducing the invasiveness of the tumor cells, suggesting a potential role for these agents in the adjuvant treatment of pancreatic cancer.

Topics: 3T3 Cells; Adenocarcinoma; alpha Catenin; Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Cycle; Cell Cycle Proteins; Cell Division; Collagen; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Cyclins; Cyclooxygenase 2; Cytoskeletal Proteins; Drug Combinations; Enzyme Induction; Gene Expression Regulation, Neoplastic; Humans; Isoenzymes; Laminin; Ligands; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Membrane Proteins; Mice; Neoplasm Invasiveness; Neoplasm Proteins; Pancreatic Neoplasms; Prostaglandin D2; Prostaglandin-Endoperoxide Synthases; Proteoglycans; Receptors, Cytoplasmic and Nuclear; Thiazoles; Thiazolidinediones; Trans-Activators; Transcription Factors; Tumor Cells, Cultured; Tumor Suppressor Proteins