Prostaglandin E2 stimulates the production of vascular endothelial growth factor through the E-prostanoid-2 receptor in cultured human lung fibroblasts

Prostaglandin E2 breaks down pericyte-endothelial cell interaction via EP1 and EP4-dependent downregulation of pericyte N-cadherin, connexin-43, and R-Ras

A close association between pericytes and endothelial cells (ECs) is crucial to the stability and function of capillary blood vessels and microvessels. The loss or dysfunction of pericytes results in significant disruption of these blood vessels as observed in pathological conditions, including cancer, diabetes, stroke, and Alzheimer’s disease. Prostaglandin E2 (PGE2) is a lipid mediator of inflammation, and its tissue concentration is elevated in cancer and neurological disorders. Here, we show that the exposure to PGE2 switches pericytes to a fast-migrating, loosely adhered phenotype that fails to intimately interact with ECs. N-cadherin and connexin-43 in adherens junction and gap junction between pericytes and ECs are downregulated by EP-4 and EP-1-dependent mechanisms, leading to breakdown of the pericyte–EC interaction. Furthermore, R-Ras, a small GTPase important for vascular normalization and vessel stability, is transcriptionally repressed by PGE2 in an EP4-dependent manner. Mouse dermal capillary vessels lose pericyte coverage substantially upon PGE2 injection into the skin. Our results suggest that EP-mediated direct disruption of pericytes by PGE2 is a key process for vascular destabilization. Restoring pericyte–EC interaction using inhibitors of PGE2 signaling may offer a therapeutic strategy in cancer and neurological disorders, in which pericyte dysfunction contributes to the disease progression.

Mapping the structure and biological functions within mesenchymal bodies using microfluidics

Organoids that recapitulate the functional hallmarks of anatomic structures comprise cell populations able to self-organize cohesively in 3D. However, the rules underlying organoid formation in vitro remain poorly understood because a correlative analysis of individual cell fate and spatial organization has been challenging. Here, we use a novel microfluidics platform to investigate the mechanisms determining the formation of organoids by human mesenchymal stromal cells that recapitulate the early steps of condensation initiating bone repair in vivo. We find that heterogeneous mesenchymal stromal cells self-organize in 3D in a developmentally hierarchical manner. We demonstrate a link between structural organization and local regulation of specific molecular signaling pathways such as NF-κB and actin polymerization, which modulate osteo-endocrine functions. This study emphasizes the importance of resolving spatial heterogeneities within cellular aggregates to link organization and functional properties, enabling a better understanding of the mechanisms controlling organoid formation, relevant to organogenesis and tissue repair.

EphA2-positive human umbilical cord-derived mesenchymal stem cells exert anti-fibrosis and immunomodulatory activities via secretion of prostaglandin E2

OBJECTIVE

Previous study has demonstrated that EphA2 is a biomarker of mesenchymal stem cells (MSCs) from human placenta or umbilical cord and is able to distinguish MSCs from fibroblasts. In this study, we further examine the potential efficacy of EphA2⁺ human umbilical cord-derived MSCs (hUC-MSCs).

MATERIALS AND METHODS

MSCs specific markers, EphA2 and CD146 expression on the surface of hUC-MSCs were determined by flow cytometry analysis. Quantitative real time polymerase chain reaction was used to examine pro-fibrotic gene expression of TGF-β1-stimulated lung fibroblast (MRC-5 cells). On the other hand, ELISA was used to analyze the content of pro-inflammatory cytokines (TNF-ɑ; and IP-10) in the LPS-activated macrophages culture supernatant.

RESULTS

The pro-fibrotic gene (TGF-β1, CTGF, fibronectin, collagen I and TIMP-1) expression in TGF-β1-activated MRC-5 cells and the pro-inflammatory cytokines (TNF-ɑ and IP-10) in the LPS-activated macrophages culture supernatant were both attenuated when in present of EphA2⁺ hUC-MSCs. Moreover, once EphA2⁺ hUC-MSCs treated with prostaglandin E2 specific inhibitor NS-398, both anti-fibrotic and anti-inflammatory effects of EphA2⁺ hUC-MSCs were abolished.

CONCLUSION

EphA2⁺ hUC-MSCs possess immunomodulatory and anti-fibrotic properties, and PGE2 plays an important role in these activities. This implies that EphA2⁺ hUC-MSCs have potentially effectiveness for treatment of acute inflammatory and chronic fibrotic lung diseases.

Thrombospondin-1 interactions regulate eicosanoid metabolism and signaling in cancer-related inflammation

The metabolism of arachidonic acid and other polyunsaturated fatty acids produces eicosanoids, a family of biologically active lipids that are implicated in homeostasis and in several pathologies that involve inflammation. Inflammatory processes mediated by eicosanoids promote carcinogenesis by exerting direct effects on cancer cells and by affecting the tumor microenvironment. Therefore, understanding how eicosanoids mediate cancer progression may lead to better approaches and chemopreventive strategies for the treatment of cancer. The matricellular protein thrombospondin-1 is involved in processes that profoundly regulate inflammatory pathways that contribute to carcinogenesis and metastatic spread. This review focuses on interactions of thrombospondin-1 and eicosanoids in the microenvironment that promote carcinogenesis and how the microenvironment can be targeted for cancer prevention to increase curative responses of cancer patients.

Female mice lacking Pald1 exhibit endothelial cell apoptosis and emphysema

Paladin (Pald1, mKIAA1274 or x99384) was identified in screens for vascular-specific genes and is a putative phosphatase. Paladin has also been proposed to be involved in various biological processes such as insulin signaling, innate immunity and neural crest migration. To determine the role of paladin we have now characterized the Pald1 knock-out mouse in a broad array of behavioral, physiological and biochemical tests. Here, we show that female, but not male, Pald1 heterozygous and homozygous knock-out mice display an emphysema-like histology with increased alveolar air spaces and impaired lung function with an obstructive phenotype. In contrast to many other tissues where Pald1 is restricted to the vascular compartment, Pald1 is expressed in both the epithelial and mesenchymal compartments of the postnatal lung. However, in Pald1 knock-out females, there is a specific increase in apoptosis and proliferation of endothelial cells, but not in non-endothelial cells. This results in a transient reduction of endothelial cells in the maturing lung. Our data suggests that Pald1 is required during lung vascular development and for normal function of the developing and adult lung in a sex-specific manner. To our knowledge, this is the first report of a sex-specific effect on endothelial cell apoptosis.

Vascular endothelial growth factor mediates ceramide 1-phosphate-stimulated macrophage proliferation

The bioactive sphingolipid ceramide 1-phosphate (C1P) regulates cell division in a variety of cell types including macrophages. However, the mechanisms involved in this action are not completely understood. In the present work we show that C1P stimulates the release of vascular endothelial growth factor (VEGF) in RAW264.7 macrophages, and that this growth factor is essential for stimulation of cell proliferation by C1P. The stimulation of VEGF release was dependent upon activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB-1 also known as Akt-1), and mitogen-activated protein kinase-kinase (MEK)/extracellularly regulated kinase-2 (ERK-2) pathways, as inhibition of these kinases with selective pharmacological inhibitors or with specific gene silencing siRNA, abrogated VEGF release. A key observation was that sequestration of VEGF with a neutralizing antibody, or treatment with VEGF siRNA abolished C1P-stimulated macrophage growth. Also, inhibition of the pathways involved in C1P-stimulated VEGF release inhibited the stimulation of macrophage growth by C1P. Moreover, blockade of VEGF receptor-2 (VEGFR-2), which is the primary receptor for VEGF, with the pharmacological inhibitor DMH4, or with specific VEGFR-2 siRNA, substantially inhibited C1P-stimulated cell growth. It can be concluded that stimulation of VEGF release is a key factor in the promotion of macrophage proliferation by C1P.

Reduced microRNA-503 expression augments lung fibroblast VEGF production in chronic obstructive pulmonary disease

Alterations in microRNA (miRNA) expression may contribute to COPD pathogenesis. In COPD, lung fibroblast repair functions are altered in multiple ways, including extracellular mediator release. Our prior study revealed miR-503 expression is decreased in COPD lung fibroblasts, although the exact role played by miR-503 is undetermined. The current study examined a role of miR-503 in cytokine, growth factor and fibronectin production by lung fibroblasts from patients with and without COPD. Primary adult lung fibroblasts were isolated from patients with or without COPD. MiR-503 expression and interleukin (IL)-6, -8, PGE2, HGF, KGF, VEGF and fibronectin release were examined with or without inflammatory cytokines, IL-1β and tumor necrosis factor (TNF)-α. MiR-503 expression was decreased in COPD lung fibroblasts. The expression of miR-503 was positively correlated with %FVC, %FEV1, and %DLco as well as IL-6, -8, PGE2, HGF, KGF, and VEGF in the absence or presence of IL-1ß/TNF-α. In addition, IL-8 and VEGF release from COPD lung fibroblasts were increased compared to those from control. Exogenous miR-503 inhibited VEGF release from primary adult and fetal lung fibroblasts but not IL-8 release. As expected, COPD fibroblasts proliferated more slowly than control fibroblasts. MiR-503 did not affect proliferation of either control or COPD lung fibroblasts. MiR-503 inhibition of VEGF protein production and mRNA was mediated by direct binding to the 3' untranslated region of VEGF mRNA. Endogenous miR-503 was differently regulated by exogenous stimulants associated with COPD pathogenesis, including IL-1ß/TNF-α, TGF-ß1 and PGE2. Endogenous miR-503 inhibition augmented VEGF release by IL-1ß/TNF-α and TGF-ß1 but not by PGE2, demonstrating selectivity of miR-503 regulation of VEGF. In conclusions, reduced miR-503 augments VEGF release from lung fibroblasts from patients with COPD. Since VEGF contributes to disturbed vasculature in COPD, altered miR-503 production might play a role in modulating fibroblast-mediated vascular homeostasis in COPD.

Mapping PTGERs to the Ovulatory Follicle: Regional Responses to the Ovulatory PGE2 Signal

Prostaglandin E2 (PGE2) is a key intrafollicular mediator of ovulation in many, if not all, mammalian species. PGE2 acts at follicular cells via four distinct PGE2 receptors (PTGERs). Within the ovulatory follicle, each cell type (e.g., oocyte, cumulus granulosa cell, mural granulosa cell, theca cell, endothelial cell) expresses a different subset of the four PTGERs. Expression of a subset of PTGERs has consequences for the generation of intracellular signals and ultimately the unique functions of follicular cells that respond to PGE2. Just as the ovulatory LH surge regulates PGE2 synthesis, the LH surge also regulates expression of the four PTGERs. The pattern of expression of the four PTGERs among follicular cells before and after the LH surge forms a spatial and temporal map of PGE2 responses. Differential PTGER expression, coupled with activation of cell-specific intracellular signals, may explain how a single paracrine mediator can have pleotropic actions within the ovulatory follicle. Understanding the role of each PTGER in ovulation may point to previously unappreciated opportunities to both promote and prevent fertility.

Prostaglandin E₂ possesses different potencies in inducing Vascular Endothelial Growth Factor and Interleukin-8 production in COPD human lung fibroblasts

We studied the role of PGE2, its biosynthetic enzymes and its receptors, in regulating the functions of lung fibroblasts through the production of Vascular Endothelial Growth Factor (VEGF) and Interleukin-8 (IL-8) in COPD subjects. Lung fibroblasts from Control (C) (n=6), Smoker (HS) (n=6) and COPD patients (n=8) were cultured, and basal PGE2, VEGF, and IL-8 measured in supernatants by ELISA. COX-1/COX-2 and EP receptors expression were assessed by western blot and by RT-PCR. Release of VEGF and IL-8 by human fetal lung fibroblasts (HFL-1; lung, diploid, human) was evaluated under different conditions. PGE2, VEGF, and IL-8 levels, COX-2, EP2, and EP4 protein expression and mRNA were increased in COPD when compared to Controls. Low concentrations of synthetic PGE2 increased the release of VEGF in HFL-1, but higher concentrations were needed to induce the release of IL-8. This effect was mimicked by an EP2 agonist and modulated by an EP4 antagonist. In the airways of COPD subjects, fibroblast-derived PGE2 may regulate angiogenesis and inflammation through the production of VEGF and IL-8 respectively, suggesting that the increase in expression of COX-2, EP2 and EP4 observed in COPD fibroblasts may contribute to steering the role of PGE2 from homeostatic to pro-inflammatory.

Phosphodiesterase-4 inhibition augments human lung fibroblast vascular endothelial growth factor production induced by prostaglandin E2

Lung fibroblasts are believed to be a major source of vascular endothelial growth factor (VEGF), which supports the survival of lung endothelial cells and modulates the maintenance of the pulmonary microvasculature. VEGF has been related to the pathogenesis of lung diseases, including chronic obstructive pulmonary disease (COPD). Prostaglandin E2 (PGE2) stimulates VEGF production from lung fibroblasts via the E-prostanoid (EP)-2 receptor. The EP2 signaling pathway uses cyclic adenosine monophosphate (cAMP) as a second messenger, and cAMP is degraded by phosphodiesterases (PDEs). This study investigates whether phosphodiesterase inhibition modulates the human lung fibroblast VEGF production induced by PGE2. Human fetal lung fibroblasts were cultured with PGE2 and PDE inhibitors. The PDE4 inhibitors roflumilast, roflumilast N-oxide, and rolipram with PGE2 increased VEGF release, as quantified in supernatant media by ELISA. In contrast, PDE3, PDE5, and PDE7 inhibitors did not affect VEGF release. Roflumilast increased VEGF release with either an EP2 or an EP4 agonist. Roflumilast augmented the cytosolic cAMP levels induced by PGE2 and VEGF release with other agents that use the cAMP signaling pathway. Roflumilast-augmented VEGF release was completely inhibited by a protein kinase A (PKA) inhibitor. Roflumilast with PGE2 increased VEGF mRNA levels, and the blockade of mRNA synthesis inhibited the augmented VEGF release. The stimulatory effect of roflumilast on VEGF release was replicated using primary healthy and COPD lung fibroblasts. These findings demonstrate that PDE4 inhibition can modulate human lung fibroblast VEGF release by PGE2 acting through the EP2 and EP4 receptor-cAMP/PKA signaling pathway. Through this action, PDE4 inhibitors such as roflumilast could contribute to the survival of lung endothelial cells.

G-protein-coupled receptor 91 and succinate are key contributors in neonatal postcerebral hypoxia-ischemia recovery

OBJECTIVE

Prompt post-hypoxia-ischemia (HI) revascularization has been suggested to improve outcome in adults and newborn subjects. Other than hypoxia-inducible factor, sensors of metabolic demand remain largely unknown. During HI, anaerobic respiration is arrested resulting in accumulation of carbohydrate metabolic intermediates. As such succinate readily increases, exerting its biological effects via a specific receptor, G-protein-coupled receptor (GPR) 91. We postulate that succinate/GPR91 enhances post-HI vascularization and reduces infarct size in a model of newborn HI brain injury.

APPROACH AND RESULTS

The Rice-Vannucci model of neonatal HI was used. Succinate was measured by mass spectrometry, and microvascular density was evaluated by quantification of lectin-stained cryosection. Gene expression was evaluated by real-time polymerase chain reaction. Succinate levels rapidly increased in the penumbral region of brain infarcts. GPR91 was foremost localized not only in neurons but also in astrocytes. Microvascular density increased at 96 hours after injury in wild-type animals; it was diminished in GPR91-null mice leading to an increased infarct size. Stimulation with succinate led to an increase in growth factors implicated in angiogenesis only in wild-type mice. To explain the mode of action of succinate/GPR91, we investigated the role of prostaglandin E2-prostaglandin E receptor 4, previously proposed in neural angiogenesis. Succinate-induced vascular endothelial growth factor expression was abrogated by a cyclooxygenase inhibitor and a selective prostaglandin E receptor 4 antagonist. This antagonist also abolished succinate-induced neovascularization.

CONCLUSIONS

We uncover a dominant metabolic sensor responsible for post-HI neurovascular adaptation, notably succinate/GPR91, acting via prostaglandin E2-prostaglandin E receptor 4 to govern expression of major angiogenic factors. We propose that pharmacological intervention targeting GPR91 could improve post-HI brain recovery.

Inhibitory effects of pitavastatin on fibrogenic mediator production by human lung fibroblasts

AIMS

Idiopathic pulmonary fibrosis continues to be a devastating clinical disorder for which there are few therapeutic options, and the pathogenesis of this disease remains largely unknown. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in cholesterol biosynthesis, and they have been reported to exert pleiotropic effects on the cellular signaling involved in tissue inflammation and in organ fibrosis/remodeling. We examined the preventive effects of statins on fibrogenic mediator expression and production in normal human lung fibroblasts (NHLF).

MAIN METHODS

NHLF were pretreated with 100nM pitavastatin or medium alone (control), and were then stimulated with transforming growth factor-β1 (TGF-β1). mRNA expression and protein secretion of several mediators from cells were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay or multiplex assay.

KEY FINDINGS

TGF-β1-induced expression or production of mediators, such as collagen-1, vascular endothelial growth factor and chemokine C-X-C motif ligand 8, in NHLF pretreated with pitavastatin was significantly suppressed with inhibition of Smad-3 phosphorylation, as compared to untreated controls. In addition, the inhibitory effects of pitavastatin were negated by addition of mevalonate.

SIGNIFICANCE

Pitavastatin appeared to inhibit TGF-β1-induced fibrogenic mediator production from lung fibroblasts via the mevalonic cascade. Although further evaluation of the signaling pathways for these phenomena is necessary, our results suggest the potential benefits of pitavastatin.

Mechanisms of growth of a pulmonary capillary network in adult lung

The present study provides new insight into structural processes remodeling pulmonary capillaries in adult lung. The data highlight mechanisms underlying the expansion and increased density of capillary segments on return to air breathing (FiO2 0.21) after injury in high oxygen (FiO2 0.75). As segments expand and increase in number, endothelial cells extend their processes to bridge the lumen and support the walls of developing interluminal structures (ILSs); endothelial-epithelial surfaces infold as a single unit (sheet) into the lumen, increasing the length of each surface and subdividing segments by loop formation and by the formation of ILSs; segments further increase in number as lumen subdivision proceeds by intussusceptive microvascular growth (IMG).

Rationale for the design of an oncology trial using a generic targeted therapy multi‑drug regimen for NSCLC patients without treatment options (Review)

Despite more than 70 years of research concerning medication for cancer treatment, the disease still remains one of the leading causes of mortality worldwide. Many cancer types lead to death within a period of months to years. The original class of chemotherapeutics is not selective for tumor cells and often has limited efficacy, while treated patients suffer from adverse side‑effects. To date, the concept of tumor‑specific targeted therapy drugs has not fulfilled its expectation to provide a key for a cure. Today, many oncology trials are designed using a combination of chemotherapeutics with targeted therapy drugs. However, these approaches have limited outcomes in most cancer indications. This perspective review provides a rationale to combine targeted therapy drugs for cancer treatment based on observations of evolutionary principles of tumor development and HIV infections. In both diseases, the mechanisms of immune evasion and drug resistance can be compared to some extent. However, only for HIV is a breakthrough treatment available, which is the highly active antiretroviral therapy (HAART). The principles of HAART and recent findings from cancer research were employed to construct a hypothetical model for cancer treatment with a multi‑drug regimen of targeted therapy drugs. As an example of this hypothesis, it is proposed to combine already marketed targeted therapy drugs against VEGFRs, EGFR, CXCR4 and COX2 in an oncology trial for non‑small cell lung cancer patients without further treatment options.

Smad3 mediates cigarette smoke extract (CSE) induction of VEGF release by human fetal lung fibroblasts

Cigarette smoke is the major cause of chronic obstructive pulmonary disease (COPD), yet pathogenic mechanisms are not fully understood. Vascular endothelial growth factor (VEGF) is one of the major regulators of endothelial cell survival and is believed to play a role in the pathogenesis of COPD. Fibroblasts are a significant source of VEGF in the lungs; however the effect of cigarette smoke exposure on VEGF release by fibroblasts is not fully understood. We hypothesized that cigarette smoke-induced disturbed VEGF release by human lung fibroblasts is a potential pathogenic mechanism that could contribute to COPD. Cigarette smoke extract (CSE) was prepared by modification of the methods of Carp and Janoff (American Review of Respiratory Disease, 1978). Human fetal lung fibroblasts (HFL-1) were exposed to different concentrations of CSE and for different durations. VEGF release into the media was measured using ELISA. TGF-β1 receptor (TβR1)/Smad3 as a potential pathway for CSE modulated VEGF release was also investigated using biochemical analyses and siRNA inhibition of Smad3 and siRNA and pharmacologic inhibition of TβR1. CSE induced VEGF release by HFL-1 in concentration and time dependent manner. This was confirmed in two additional types of primary human fetal lung fibroblasts. CSE induced Smad3 phosphorylation and nuclear translocation in HFL-1 cells. Silencing of Smad3 by siRNA not only eliminated the stimulatory effect of CSE on VEGF release but also inhibited baseline VEGF production. Suppression of TβR1 by the pharmacological inhibitor (SB431542) markedly reduced VEGF release by HFL-1 in response to CSE and this effect was confirmed by TβR1 siRNA. In contrast, nicotine inhibited VEGF release by HFL-1 in a dose and time dependent manner. Our findings indicate that CSE stimulates Smad3-mediated VEGF release by lung fibroblasts. Nicotine does not account for the CSE stimulation of VEGF in HFL-1. The ability of lung fibroblasts to produce VEGF may play a role in pathogenesis of cigarette smoke induced lung disease.

Tumor-associated stromal cells expressing E-prostanoid 2 or 3 receptors in prostate cancer: correlation with tumor aggressiveness and outcome by angiogenesis and lymphangiogenesis

OBJECTIVE

To clarify the detailed pathologic roles of prostaglandin E(2) in prostate cancer tissues, the present study investigated the clinical significance and prognostic roles of the density of tumor-associated stromal cells expressing specific receptors for prostaglandin E2, termed "E-prostanoid (EP)1-4 receptors (EP1R-4Rs)."

METHODS

The expression of each receptor was immunohistochemically examined in 114 formalin-fixed biopsy specimens. Correlations with clinicopathologic features were investigated in these specimens. Angiogenesis and lymphangiogenesis were measured by the percentage of CD34-stained vessels (microvessel density) and D2-40-stained vessels (lymph vessel density). The relationships between the density of each EPR-stained cells and the microvessel density or lymph vessel density were evaluated in 62 prostate cancer tissues obtained by radical surgery for more detailed analysis in a wider area of prostate cancer tissue.

RESULTS

The density of tumor-associated cells with EP2R expression was positively associated with the N (P<.001) and M (P=.002) stages. Similarly, EP3R-positive stromal cell density was significantly associated with the N (P=.033) and M (P=.026) stages. The density of EP2R- and EP3R-stained cells correlated with the microvessel density (r=0.42, P<.001) and lymph vessel density (r=0.36, P=.012), respectively. A greater density of EP2R-stained cells was recognized as an independent predictor of progression (hazard ratio 7.26, P=.002) on multivariate analysis.

CONCLUSION

EP2R- and EP3R-stained cells might play important roles in tumor progression, angiogenesis, and lymphangiogenesis in prostate cancer. The density of EP2R-stained stromal cells could offer a useful predictor of biochemical recurrence after radical surgery.

Distinct PKA and Epac compartmentalization in airway function and plasticity

Asthma and chronic obstructive pulmonary disease (COPD) are obstructive lung diseases characterized by airway obstruction, airway inflammation and airway remodelling. Next to inflammatory cells and airway epithelial cells, airway mesenchymal cells, including airway smooth muscle cells and (myo)fibroblasts, substantially contribute to disease features by the release of inflammatory mediators, smooth muscle contraction, extracellular matrix deposition and structural changes in the airways. Current pharmacological treatment of both diseases intends to target the dynamic features of the endogenous intracellular suppressor cyclic AMP (cAMP). This review will summarize our current knowledge on cAMP and will emphasize on key discoveries and paradigm shifts reflecting the complex spatio-temporal nature of compartmentalized cAMP signalling networks in health and disease. As airway fibroblasts and airway smooth muscle cells are recognized as central players in the development and progression of asthma and COPD, we will focus on the role of cAMP signalling in their function in relation to airway function and plasticity. We will recapture on the recent identification of cAMP-sensing multi-protein complexes maintained by cAMP effectors, including A-kinase anchoring proteins (AKAPs), proteins kinase A (PKA), exchange protein directly activated by cAMP (Epac), cAMP-elevating seven-transmembrane (7TM) receptors and phosphodiesterases (PDEs) and we will report on findings indicating that the pertubation of compartmentalized cAMP signalling correlates with the pathopysiology of obstructive lung diseases. Future challenges include studies on cAMP dynamics and compartmentalization in the lung and the development of novel drugs targeting these systems for therapeutic interventions in chronic obstructive inflammatory diseases.

Multifaceted roles of PGE2 in inflammation and cancer

Prostaglandin E(2) (PGE(2)) is a bioactive lipid that elicits a wide range of biological effects associated with inflammation and cancer. PGE(2) exerts diverse effects on cell proliferation, apoptosis, angiogenesis, inflammation, and immune surveillance. This review concentrates primarily on gastrointestinal cancers, where the actions of PGE(2) are most prominent, most likely due to the constant exposure to dietary and environmental insults and the intrinsic role of PGE(2) in tissue homeostasis. A discussion of recent efforts to elucidate the complex and interconnected pathways that link PGE(2) signaling with inflammation and cancer is provided, supported by the abundant literature showing a protective effect of NSAIDs and the therapeutic efficacy of targeting mPGES-1 or EP receptors for cancer prevention. However, suppressing PGE(2) formation as a means of providing chemoprotection against all cancers may not ultimately be tenable, undoubtedly the situation for patients with inflammatory bowel disease. Future studies to fully understand the complex role of PGE(2) in both inflammation and cancer will be required to develop novel strategies for cancer prevention that are both effective and safe.