Prostaglandin E2 induces fibroblast growth factor 9 via EP3-dependent protein kinase Cdelta and Elk-1 signaling

Exploration of the molecular linkage between endometriosis and Crohn disease by bioinformatics methods

BACKGROUND

Endometriosis (EMT) is a common disease in reproductive-age woman and Crohn disease (CD) is a chronic inflammatory disorder in gastrointestinal tract. Previous studies reported that patients with EMT had an increased risk of CD. However, the linkage between EMT and CD remains unclear. In this study, we aimed to investigate the potential molecular mechanism of EMT and CD.

METHODS

The microarray data of EMT and CD were downloaded from Gene Expression Omnibus. Common genes of EMT and CD were obtained to perform the Gene Ontology and Kyoto Encyclopedia of Gene Genomes enrichments. The protein-protein interaction network was constructed by Cytoscape software and the hub genes were identified by CytoHubba plug-in. Finally we predicted the transcription factors (TFs) of hub genes and constructed a TFs-hub genes regulation network.

RESULTS

A total of 50 common genes were identified. Kyoto Encyclopedia of Gene Genomes enrichment showed that the common genes mainly enriched in MAPK pathway, VEGF pathway, Wnt pathway, TGF-beta pathway, and Ras pathway. Fifteen hub genes were collected from the protein-protein interaction network, including FMOD, FRZB, CPE, SST, ISG15, EFEMP1, KDR, ADRA2A, FZD7, AQP1, IGFBP5, NAMPT, PLUA, FGF9, and FHL2. Among them, FGF9, FZD7, IGFBP5, KDR, and NAMPT were both validated in the other 2 datasets. Finally TFs-hub genes regulation network were constructed.

CONCLUSION

Our findings firstly revealed the linkage between EMT and CD, including inflammation, angiogenesis, immune regulation, and cell behaviors, which may lead to the risk of CD in EMT. FGF9, FZD7, IGFBP5, KDR, and NAMPT may closely relate to the linkage.

Progesterone resistance in endometriosis: A pathophysiological perspective and potential treatment alternatives

Background

Endometriosis is a common gynecological disease affecting women of reproductive age. Patients with endometriosis frequently experience severe chronic pain and have higher chances to experience infertility. Progesterone resistance is a major problem that develops during the medical treatment of endometriosis, which often leads to treatment failure of hormonal therapies. Previous studies indicated that the dysregulation of progesterone receptors (PR) is the primary factor leading to progesterone resistance in endometriosis.

Methods

This review article systematically reviewed and summarized findings extracted from previously published papers available on PubMed, encompassing both experimental studies and clinical trials.

Main findings

Various determinants influencing PR expression in endometriosis have been identified, including the environmental toxins, microRNAs, cell signaling pathways, genetic mutations, and the pro-inflammatory cytokines. The selective estrogen/progesterone receptor modulators have emerged as novel therapeutic approaches for treating endometriosis, offering potential improvements in overcoming progesterone resistance.

Conclusion

Concerns and limitations persist despite the newly developed drugs. Therefore, studies on unraveling new therapeutic targets based on the molecular mechanisms of progesterone resistance is warranted for the development potential alternatives to overcome hormonal treatment failure in endometriosis.

PGE2 -EP3 axis promotes brown adipose tissue formation through stabilization of WTAP RNA methyltransferase

Brown adipose tissue (BAT) functions as a thermogenic organ and is negatively associated with cardiometabolic diseases. N⁶ -methyladenosine (m⁶ A) modulation regulates the fate of stem cells. Here, we show that the prostaglandin E₂ (PGE₂ )-E-prostanoid receptor 3 (EP3) axis was activated during mouse interscapular BAT development. Disruption of EP3 impaired the browning process during adipocyte differentiation from pre-adipocytes. Brown adipocyte-specific depletion of EP3 compromised interscapular BAT formation and aggravated high-fat diet-induced obesity and insulin resistance in vivo. Mechanistically, activation of EP3 stabilized the Zfp410 mRNA via WTAP-mediated m⁶ A modification, while knockdown of Zfp410 abolished the EP3-induced enhancement of brown adipogenesis. EP3 prevented ubiquitin-mediated degradation of WTAP by eliminating PKA-mediated ERK1/2 inhibition during brown adipocyte differentiation. Ablation of WTAP in brown adipocytes abrogated the protective effect of EP3 overexpression in high-fat diet-fed mice. Inhibition of EP3 also retarded human embryonic stem cell differentiation into mature brown adipocytes by reducing the WTAP levels. Thus, a conserved PGE₂ -EP3 axis promotes BAT development by stabilizing WTAP/Zfp410 signaling in a PKA/ERK1/2-dependent manner.

Maternal Recognition of Pregnancy in the Horse: Are MicroRNAs the Secret Messengers?

The signal for maternal recognition of pregnancy (MRP) has still not been identified in the horse. High-throughput molecular biology at the embryo-maternal interface has substantially contributed to the knowledge on pathways affected during MRP, but an integrated study in which proteomics, transcriptomics and miRNA expression can be linked directly is currently lacking. The aim of this study was to provide such analysis. Endometrial biopsies, uterine fluid, embryonic tissues, and yolk sac fluid were collected 13 days after ovulation during pregnant and control cycles from the same mares. Micro-RNA-Sequencing was performed on all collected samples, mRNA-Sequencing on the same tissue samples and mass spectrometry was conducted previously on the same fluid samples. Differential expression of miRNA, mRNA and proteins showed high conformity with literature and confirmed involvement in pregnancy establishment, embryo quality, steroid synthesis and prostaglandin regulation, but the link between differential miRNAs and their targets was limited and did not indicate the identity of an unequivocal signal for MRP in the horse. Differential expression at the embryo-maternal interface was prominent, highlighting a potential role of miRNAs in embryo-maternal communication during early pregnancy in the horse. These data provide a strong basis for future targeted studies.

Upregulation of cancer-associated gene expression in activated fibroblasts in a mouse model of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH), characterized by chronic inflammation and fibrosis, is predicted to be the leading cause of cirrhosis and hepatocellular carcinoma (HCC) in the next decade. Although recent evidence suggests the importance of fibrosis as the strongest determinant of HCC development, the molecular mechanisms underlying NASH-induced carcinogenesis still remain unclear. Here we performed RNA sequencing analysis to compare gene expression profiles of activated fibroblasts prepared from two distinct liver fibrosis models: carbon tetrachloride–induced fibrosis as a model without obesity and HCC and genetically obese melanocortin 4 receptor–deficient (MC4R-KO) mice fed Western diet, which develop steatosis, NASH, and eventually HCC. Our data showed that activated fibroblasts exhibited distinct gene expression patterns in each etiology, and that the ‘pathways in cancer’ were selectively upregulated in the activated fibroblasts from MC4R-KO mice. The most upregulated gene in these pathways was fibroblast growth factor 9 (FGF9), which was induced by metabolic stress such as palmitate. FGF9 exerted anti-apoptotic and pro-migratory effects in fibroblasts and hepatoma cells in vitro and accelerated tumor growth in a subcutaneous xenograft model. This study reveals upregulation of cancer-associated gene expression in activated fibroblasts in NASH, which would contribute to the progression from NASH to HCC.

Hypoxia: The force of endometriosis

AIM

Summarize recent findings of how hypoxia regulates numerous important processes to facilitate the implantation, proliferation and progression of ectopic endometriotic lesions.

METHODS

Most up-to-date evidences about how hypoxia contributes to the disease pathogenesis of endometriosis and potential therapeutic approaches were collected by conducting a comprehensive search of medical literature electronic databases. Quality of data was analyzed by experienced experts including gynecologist and basic scientists.

RESULTS

Uterus is a highly vascularized organ, which makes endometrial cells constantly expose to high concentration of oxygen. When endometrial tissues shed off from the eutopic uterus and retrograde to the peritoneal cavity, they face severe hypoxic stress. Even with successful implantation to ovaries or peritoneum, the hypoxic stress remains as a critical issue because endometrial cells are used to live in the well-oxygenated environment. Under the hypoxia condition, cells undergo epigenetic modulation and evolve several survival processes including steroidogenesis, angiogenesis, inflammation and metabolic switch. The complex gene regulatory network driven by hypoxia ensures endometriotic cells can survive under the hostile peritoneal microenvironment.

CONCLUSION

Hypoxia plays critical roles in promoting pathological processes to facilitate the development of endometriosis. Targeting hypoxia-mediated gene network represents an alternative approach for the treatment of endometriosis.

Systematic analysis of hsa-miR-363 gene overexpression pattern in endometrial stromal cells

Endometriosis is a benign disease, but has invasion and metastasis characteristics similar to malignant tumors. Clinically, it is a difficult problem of gynecological clinical treatment for its high recurrence rate. It has been confirmed that miR-363 was downregulated in endometriosis tissues and miR-363 overexpression inhibited the invasion ability of endometrial stromal cells (ESCs). In order to explore the potential mechanism of miR-363-reduced ESC migration and invasion progression, we sought to demonstrate the targeted mRNA expression levels of miR-363 through microarray, and performed cluster analysis to identify potential functions of these targeted genes in ESCs. The wound migration assay showed that there was an observable trend of cell migration potential decrease after transfection with hsa-miR-363. The qRT-PCR result showed that compared to miR-363 negative control cell group, miR-363 was upregulated 3,264.58-fold after miR-363 lentiviral transfection in miR-363 mimics group. The microarray data showed that compared to ESCs miR-363 negative control cell group, 249 genes were upregulated in ESCs miR-363 mimics cells group, and 139 genes were downregulated. Gene Ontology analysis and the pathway analysis data demonstrated that these target genes are mainly involved in cell migration, cell adhesion and invasion, proliferation, apoptosis, alteration of endometrial cells and some related signaling pathways. Our study explored the gene expression pattern after miR-363 overexpression, which could expand the insights into the miR-363 function and molecular mechanisms in endometriosis.

FGF-FGFR Mediates the Activity-Dependent Dendritogenesis of Layer IV Neurons during Barrel Formation

Fibroblast growth factors (FGFs) and FGF receptors (FGFRs) are known for their potent effects on cell proliferation/differentiation and cortical patterning in the developing brain. However, little is known regarding the roles of FGFs/FGFRs in cortical circuit formation. Here we show that Fgfr1/2/3 and Fgf7/9/10/22 mRNAs are expressed in the developing primary somatosensory (S1) barrel cortex. Barrel cortex layer IV spiny stellate cells (bSCs) are the primary recipients of ascending sensory information via thalamocortical axons (TCAs). Detail quantification revealed distinctive phases for bSC dendritogenesis: orienting dendrites toward TCAs, adding de novo dendritic segments, and elongating dendritic length, while maintaining dendritic patterns. Deleting Fgfr1/2/3 in bSCs had minimal impact on dendritic polarity but transiently increased the number of dendritic segments. However, 6 d later, FGFR1/2/3 loss of function reduced dendritic branch numbers. These data suggest that FGFs/FGFRs have a role in stabilizing dendritic patterning. Depolarization of cultured mouse cortical neurons upregulated the levels of several Fgf/Fgfr mRNAs within 2 h. In vivo, within 6 h of systemic kainic acid administration at postnatal day 6, mRNA levels of Fgf9, Fgf10, Fgfr2c, and Fgfr3b in S1 cortices were enhanced, and this was accompanied by exuberant dendritogenesis of bSCs by 24 h. Deleting Fgfr1/2/3 abolished kainic acid-induced bSC dendritic overgrowth. Finally, FGF9/10 gain of function also resulted in extensive dendritogenesis. Together, our data suggest that FGFs/FGFRs can be regulated by glutamate transmission to modulate/stabilize bSC dendritic complexity. Both male and female mice were used for our study.SIGNIFICANCE STATEMENT Glutamatergic transmission plays critical roles in cortical circuit formation. Its dysregulation has been proposed as a core factor in the etiology of many neurological diseases. We found that excessive glutamate transmission upregulated mRNA expression of Fgfrs and their ligands Fgfs Deleting Fgfr1/2/3 not only impaired bSC dendritogenesis but also abolished glutamate transmission-induced dendritic overgrowth. Overexpressing FGF9 or FGF10 in cortical glutamatergic neurons results in excessive dendritic outgrowth within 24 h, resembling the changes induced by excessive glutamate transmission. Our findings provide strong evidence for the physiological role of fibroblast growth factors (FGFs) and FGF receptors (FGFRs) in establishing and maintaining cortical circuits. Perturbing the expression levels of FGFs/FGFRs by excessive glutamatergic neurotransmission could lead to abnormal neuronal circuits, which may contribute to neurological and psychiatric disease.

Rostral Ventrolateral Medulla EP3 Receptor Mediates the Sympathoexcitatory and Pressor Effects of Prostaglandin E2 in Conscious Rats

Whereas few studies have dealt with the central sympathoexcitatory action of the inflammatory prostanoid prostaglandin E₂ (PGE₂), there is no information on the expression and cardiovascular function of different PGE₂ (EP) receptors in one of the major cardiovascular-regulating nuclei, the rostral ventrolateral medulla (RVLM). The current study aimed at filling this knowledge gap as well as elucidating the implicated molecular mechanisms. To achieve these goals, we showed the expression of EP2, EP3, and EP4 receptors in the RVLM and investigated their cardiovascular roles in conscious rats, ex vivo as well as in cultured PC12 cells. Intra-RVLM PGE₂ significantly increased blood pressure and sympathetic dominance (spectral analysis). Studies with selective EP receptor subtype agonists and antagonists showed that these PGE₂-evoked responses were only replicated by intra-RVLM activation of the EP3 receptor with its agonist sulprostone. The RVLM of PGE₂-treated rats exhibited increases in c-Fos expression and extracellular signal-regulated kinase 1/2 and neuronal nitric oxide synthase phosphorylation along with oxidative stress, and PGE₂ increased l-glutamate release in PC12 cells (surrogates of RVLM neurons). Abrogation of the PGE₂-evoked pressor and biochemical responses only occurred following EP3 receptor blockade (N-[(5-Bromo-2-methoxyphenyl)sulfonyl]-3-[2-(2-naphthalenylmethyl)phenyl]-2-propenamide, L-798106). These findings suggest the dependence of RVLM PGE₂-mediated sympathoexcitation/pressor response on local EP3 receptor signaling in conscious rats, and highlight central EP3 receptor blockade as a potential therapeutic modality for hypertension management.

Prostaglandin E2 stimulates urokinase-type plasminogen activator receptor via EP2 receptor-dependent signaling pathways in human AGS gastric cancer cells

Aberrant expression of urokinase-type plasminogen activator receptor (uPAR) has been observed in human gastric cancers. Prostaglandin E₂ (PGE₂ ), whose biosynthesis is catalyzed by cyclooxygenase-2 (COX-2), is implicated in cancer metastasis; however, the cellular and molecular mechanisms of PGE₂ -driven uPAR expression are yet to be elucidated in human gastric cancer AGS cells. In this study, we showed that PGE₂ induces uPAR expression in concentration- and time-dependent manners. Furthermore, using antagonists and siRNA, we found that among the four subtypes of PGE₂ receptors, EP2 receptors are involved in PGE₂ -induced uPAR expression. PGE₂ induced the activation of Src, epidermal growth factor receptor (EGFR), c-Jun NH₂ -terminal kinase (JNK), extracellular signal-regulated kinase (Erk), and p38 mitogen activated protein kinase (p38 MAPK). Specific inhibitor and mutagenesis studies showed that Src, EGFR, JNK1/2, and Erk1/2 are involved in PGE₂ -induced uPAR expression. PGE₂ induces EP2-dependent phosphorylation of Src, while the activation of Src-dependent EGFR leads to the phosphorylation of JNK1/2 and Erk1/2. Deletion and site-directed mutagenesis studies demonstrated the involvement of transcription factor activator protein (AP)-1 and nuclear factor-kappa B (NF-κB) in PGE₂ -induced uPAR expression. EGFR-dependent MAPKs (JNK1/2 and Erk1/2) function as the upstream signaling molecules in the activation of AP-1 and NF-κB, respectively. AGS cells pre-treated with PGE₂ showed remarkably enhanced invasiveness, which was partially abrogated by uPAR-neutralizing antibodies. To the best of our knowledge, this is the first report that PGE₂ -induced uPAR expression, which stimulates invasiveness of human gastric cancer AGS cells, is mediated by the EP2 receptor-dependent Src/EGFR/JNK1/2, Erk1/2/AP-1, and Src/EGFR/JNK1/2, Erk1/2/NF-κB cascades. © 2016 Wiley Periodicals, Inc.

Down-regulated CFTR During Aging Contributes to Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a hyper-proliferative disease of the aging prostate; however, the exact mechanism underlying the development of BPH remains incompletely understood. The present study investigated the possible involvement of the cystic fibrosis transmembrane conductance regulator (CFTR), which has been previously shown to negatively regulate nuclear factor-κB (NF-κB)/cyclooxygenase 2 (COX2)/prostaglandin E2 (PGE2) pathway, in the pathogenesis of BPH. Our results showed decreasing CFTR and increasing COX2 expression in rat prostate tissues with aging. Furthermore, suppression of CFTR led to increased expression of COX2 and over-production of PGE2 in a normal human prostate epithelial cell line (PNT1A) with elevated NF-κB activity. PGE2 stimulated the proliferation of primary rat prostate stromal cells but not epithelial cells, with increased PCNA expression. In addition, the condition medium from PNT1A cells after inhibition or knockdown of CFTR promoted cell proliferation of prostate stromal cells which could be reversed by COX2 or NF-κB inhibitor. More importantly, the involvement of CFTR in BPH was further demonstrated by the down-regulation of CFTR and up-regulation of COX2/NF-κB in human BPH samples. The present results suggest that CFTR may be involved in regulating PGE2 production through its negative regulation on NF-κB/COX2 pathway in prostate epithelial cells, which consequently stimulates cell growth of prostate stromal cells. The overstimulation of prostate stromal cell proliferation by down-regulation of CFTR-enhanced PGE2 production and release during aging may contribute to the development of BPH.

Abnormal Expression of Prostaglandins E2 and F2α Receptors and Transporters in Patients with Endometriosis

Objective. To investigate the level of expression of prostaglandin receptivity and uptake factors in eutopic and ectopic endometrium of women with endometriosis. Design. Prospective study. Setting. Human reproduction research laboratory. Patients. Seventy-eight patients with endometriosis and thirty healthy control subjects. Intervention(s). Endometrial and endometriotic tissue samples were obtained during laparoscopic surgery. Main Outcome Measure(s). Real-time polymerase chain reaction assay of mRNA encoding prostaglandin E2 receptors (EP1, EP2, EP3, and EP4), prostaglandin F2α receptor (FP), prostaglandin transporter (PGT), and multidrug resistance-associated protein 4 (MRP4); immunohistochemical localization of expressed proteins. Results. Marked increases in receptors EP3, EP4, and FP and transporters PGT and MRP4 in ectopic endometrial tissue were noted, without noticeable change associated with disease stage. An increase in EP3 expression and decreases in FP and PGT were observed in the eutopic endometrium of endometriosis patients in conjunction with the phases of the menstrual cycle. Conclusion(s). This study is the first to demonstrate a possible relationship between endometriosis and enhanced prostaglandin activity. In view of the wide range of prostaglandin functions, increasing cell receptivity and facilitating uptake in endometrial tissue could contribute to the initial steps of overgrowth and have an important role to play in the pathogenesis and symptoms of this disease.

Prostaglandin Transporter (PGT/SLCO2A1) Protects the Lung from Bleomycin-Induced Fibrosis

Prostaglandin (PG) E₂ exhibits an anti-fibrotic effect in the lung in response to inflammatory reactions and is a high-affinity substrate of PG transporter (SLCO2A1). The present study aimed to evaluate the pathophysiological relevance of SLCO2A1 to bleomycin (BLM)-induced pulmonary fibrosis in mice. Immunohistochemical analysis indicated that Slco2a1 protein was expressed in airway and alveolar type I (ATI) and II (ATII) epithelial cells, and electron-microscopic immunohistochemistry further demonstrated cell surface expression of Slco2a1 in ATI cells in wild type (WT) C57BL/6 mice. PGE₂ uptake activity was abrogated in ATI-like cells from Slco2a1-deficient (Slco2a1^-/-) mice, which was clearly observed in the cells from WT mice. Furthermore, the PGE₂ concentrations in lung tissues were lower in Slco2a1^-/- than in WT mice. The pathological relevance of SLCO2A1 was further studied in mouse BLM-induced pulmonary fibrosis models. BLM (1 mg/kg) or vehicle (phosphate buffered saline) was intratracheally injected into WT and Slco2a1^-/- mice, and BLM-induced fibrosis was evaluated on day 14. BLM induced more severe fibrosis in Slco2a1^-/- than in WT mice, as indicated by thickened interstitial connective tissue and enhanced collagen deposition. PGE₂ levels were higher in bronchoalveolar lavage fluid, but lower in lung tissues of Slco2a1^-/- mice. Transcriptional upregulation of TGF-β1 was associated with enhanced gene transcriptions of downstream targets including plasminogen activator inhitor-1. Furthermore, Western blot analysis demonstrated a significant activation of protein kinase C (PKC) δ along with a modest activation of Smad3 in lung from Slco2a1^-/- mice, suggesting a role of PKCδ associated with TGF-β signaling in aggravated fibrosis in BLM-treated Slco2a1^-/- mice. In conclusion, pulmonary PGE₂ disposition is largely regulated by SLCO2A1, demonstrating that SLCO2A1 plays a critical role in protecting the lung from BLM-induced fibrosis.

Genes Downregulated in Endometriosis Are Located Near the Known Imprinting Genes

There is now accumulating evidence that endometriosis is a disease associated with an epigenetic disorder. Genomic imprinting is an epigenetic phenomenon known to regulate DNA methylation of either maternal or paternal alleles. We hypothesize that hypermethylated endometriosis-associated genes may be enriched at imprinted gene loci. We sought to determine whether downregulated genes associated with endometriosis susceptibility are associated with chromosomal location of the known paternally and maternally expressed imprinting genes. Gene information has been gathered from National Center for Biotechnology Information database geneimprint.com. Several researchers have identified specific loci with strong DNA methylation in eutopic endometrium and ectopic lesion with endometriosis. Of the 29 hypermethylated genes in endometriosis, 19 genes were located near 45 known imprinted foci. There may be an association of the genomic location between genes specifically downregulated in endometriosis and epigenetically imprinted genes.

Hormonal therapy deregulates prostaglandin-endoperoxidase synthase 2 (PTGS2) expression in endometriotic tissues

CONTEXT

Endometriosis is a common gynecologic condition characterized by an important inflammatory process mediated by the prostaglandin pathway. Oral contraceptives are the treatment of choice for symptomatic endometriotic women. However the effects of oral contraceptives use and prostaglandin pathway in endometriotic women are actually still unknown.

OBJECTIVE

To investigate the expression of prostaglandin pathway key genes in endometriotic tissue, affected or not by hormonal therapy, as compared with healthy endometrial tissue.

DESIGN

This was a comparative laboratory study.

SETTING

This study was conducted in a tertiary-care university hospital.

PATIENTS

Seventy-six women, with (n = 46) and without (n = 30) histologically proven endometriosis.

MAIN OUTCOME MEASURES

Prostaglandin-endoperoxidase synthase (PTGS)1, PTGS2, prostaglandin E receptor (PTGER)1, PTGER2, PTGER3, and PTGER4 mRNA levels in endometrium of disease-free women and in eutopic and ectopic endometrium of endometriosis-affected women. PTGS2 expression was further investigated by immunohistochemistry, using specific monoclonal antibodies. PTGS2 expression was analyzed at mRNA and protein levels and correlated with taking hormonal treatment.

RESULTS

PTGS2 expression was significantly increased in eutopic and ectopic endometrium as compared with healthy tissue (induction of 9.6- and 6.3-fold, respectively; P = .001). PTGS2 immunoreactivity increased gradually from normal endometrium to eutopic and ectopic endometrium (h-score of 96.7 ± 55.0, 128.3 ± 66.1, and 226.7 ± 62.6, respectively, P < .001). PTGER2, PTGER3, and PTGER4 expression increased significantly and gradually from normal to eutopic and ectopic endometrium, whereas PTGER1 remained unchanged. Patients under hormonal treatment had a higher PTGS2 expression at transcriptional and protein levels as compared with those without treatment (P = .002 and P = .025, respectively).

CONCLUSIONS

Prostaglandin pathway is strongly deregulated in eutopic and ectopic endometrium of women suffering from endometriosis for the benefit of an increased PTGS2 expression. We show for the first time that hormonal treatment appears to enhance even more PTGS2 expression. These results contribute to explain why medical treatment could fail to control endometriosis progression.

Overexpression of FGF9 in colon cancer cells is mediated by hypoxia-induced translational activation

Human fibroblast growth factor 9 (FGF9) is a potent mitogen involved in many physiological processes. Although FGF9 messenger RNA (mRNA) is ubiquitously expressed in embryos, FGF9 protein expression is generally low and restricted to a few adult organs. Aberrant expression of FGF9 usually results in human malignancies including cancers, but the mechanism remains largely unknown. Here, we report that FGF9 protein, but not mRNA, was increased in hypoxia. Two sequence elements, the upstream open reading frame (uORF) and the internal ribosome entry site (IRES), were identified in the 5' UTR of FGF9 mRNA. Functional assays indicated that FGF9 protein synthesis was normally controlled by uORF-mediated translational repression, which kept the protein at a low level, but was upregulated in response to hypoxia through a switch to IRES-dependent translational control. Our data demonstrate that FGF9 IRES functions as a cellular switch to turn FGF9 protein synthesis ‘on’ during hypoxia, a likely mechanism underlying FGF9 overexpression in cancer cells. Finally, we provide evidence to show that hypoxia-induced translational activation promotes FGF9 protein expression in colon cancer cells. Altogether, this dynamic working model may provide a new direction in anti-tumor therapies and cancer intervention.

Augmented epithelial multidrug resistance-associated protein 4 expression in peritoneal endometriosis: regulation by lipoxin A(4)

OBJECTIVE

To compare the expression of the prostaglandin (PG) E(2) transporter multidrug resistance-associated protein 4 (MRP4) in eutopic and ectopic endometrial tissue from endometriosis patients with that of control subjects and to examine whether MRP4 is regulated by the antiinflammatory lipid lipoxin A(4) (LXA(4)) in endometriotic epithelial cells.

DESIGN

Molecular analysis in human samples and a cell line.

SETTING

Two university hospitals and a private clinic.

PATIENT(S)

A total of 59 endometriosis patients and 32 age- and body mass index-matched control subjects undergoing laparoscopy or hysterectomy.

INTERVENTION(S)

Normal, eutopic, and ectopic endometrial biopsies as well as peritoneal fluid were obtained during surgery performed during the proliferative phase of the menstrual cycle. 12Z endometriotic epithelial cells were used for in vitro mechanistic studies.

MAIN OUTCOME MEASURE(S)

Tissue MRP4 mRNA levels were quantified by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and localization was analyzed with the use of immunohistochemistry. Cellular MRP4 mRNA and protein were quantified by qRT-PCR and Western blot, respectively. PGE(2) was measured in peritoneal fluid and cell supernatants using an enzyme immunoassay (EIA).

RESULT(S)

MRP4 was expressed in eutopic and ectopic endometrium, where it was overexpressed in peritoneal lesions and localized in the cytoplasm of glandular epithelial cells. LXA(4) attenuated MRP4 mRNA and protein levels in endometriotic epithelial cells in a dose-dependent manner, while not affecting the expression of enzymes involved in PGE(2) metabolism. Investigations employing receptor antagonists and small interfering RNA revealed that this occurred through estrogen receptor α. Accordingly, LXA(4) treatment inhibited extracellular PGE(2) release.

CONCLUSION(S)

We report for the first time that MRP4 is expressed in human endometrium, elevated in peritoneal endometriosis, and modulated by LXA(4) in endometriotic epithelial cells.

Overexpression of galectin-3 enhances migration of colon cancer cells related to activation of the K-Ras-Raf-Erk1/2 pathway

BACKGROUND

Galectin-3 has been independently correlated with malignant behavior in human colon cancer. The involvement of galectin-3 in the invasiveness of colon cancer cells remains to be determined. We investigated whether galectin-3 was involved in the colon cancer cell migration mediated by certain kinase pathways.

METHODS

We studied 2 colon cancer cell lines (DLD-1 and Caco2) and clinical samples. Immunostaining and Western blotting were used to analyze the expression of galectin-3 in vitro and in the clinical samples. Short hairpin RNA and overexpression of galectin-3 were used to study loss- and gain-of-function in a wound-healing assay and a Transwell migration assay, and Western blotting was used to study the Ras-Raf signaling pathway.

RESULTS

Galectin-3 was expressed at lower levels in DLD-1 than in Caco2 cells. The lower galectin-3 level in DLD-1 cells was associated with decreased cell migration, in comparison with that of Caco2 cells. Overexpression of galectin-3 increased the migration rate of DLD-1, while knockdown of galectin-3 decreased the migration. Overexpression of galectin-3 was correlated with increased lamellipodia formation and distal lung localization in a mouse model. The galectin-3 enhancement of DLD-1 cell migration was mediated by K-Ras, Raf and Erk1/2 pathway activation, but not the H-Ras, p38, or JNK activation.

CONCLUSIONS

Galectin-3 plays an important role in regulating colon cancer cell migration and potential distal localization. The galectin-3 enhancement of cell migration is mediated through the K-Ras-Raf-Erk1/2 pathway. Specific targeting of the K-Ras-Raf-Erk1/2 pathway may be useful for treating colon cancers associated with increased galectin-3 expression.

Suppression of annexin A2 by prostaglandin E₂ impairs phagocytic ability of peritoneal macrophages in women with endometriosis

STUDY QUESTION

Is annexin A2 involved in the reduced phagocytic ability of macrophages in endometriosis?

SUMMARY ANSWER

Data from women with endometriosis and a murine model of the disease show that expression of annexin A2 in peritoneal macrophages is inhibited by prostaglandin E2 (PGE2) and this impairs the phagocytic ability of macrophages.

WHAT IS ALREADY KNOWN

Endometriosis is a chronic inflammatory disease that recruits many immune cells, especially macrophages, to the peritoneal cavity. The phagocytic ability of peritoneal macrophages isolated from women with endometriosis is reduced.

STUDY DESIGN, SIZE, DURATION

A laboratory study. Thirty-five patients (20 with and 15 without endometriosis) of reproductive age with normal menstrual cycles were recruited.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peritoneal macrophages isolated from women with or without endometriosis were cultured and treated with vehicle, PGE2 and different EP receptor agonists, and the expression of annexin A2 was quantified by RT-PCR and western blotting. Annexin A2 was knocked down (by small interfering RNA) in normal macrophages or overexpressed (by treatment with recombinant protein) in endometriotic macrophages and their phagocytic ability was measured by flow cytometry. Peritoneal macrophages were isolated from a mouse model of endometriosis and treated with PGE2 or cyclo-oxygenase (COX) inhibitors, and annexin A2 mRNA was quantified.

MAIN RESULTS AND THE ROLE OF CHANCE

Levels of annexin A2 were markedly reduced in peritoneal macrophages from women with endometriosis versus controls (mRNA: P < 0.01). The level of annexin A2 mRNA in the macrophages was reduced by PGE2 (P < 0.01/P < 0.05 in women without/with endometriosis versus control) via the EP2/EP4 receptor-dependent signaling pathway. Treatment with PGE2 or knockdown of annexin A2 inhibited the phagocytic ability of macrophages (P < 0.05 versus control), while treatment with annexin A2 recombinant protein enhanced phagocytosis. Autologous transplantation animal studies further confirmed that levels of annexin A2 in peritoneal macrophages were markedly reduced in mice treated with PGE2 (P < 0.01 versus control). In contrast, treatment with COX inhibitors to inhibit PGE2 production enhanced annexin A2 expression in peritoneal macrophages (P < 0.05 versus control).

LIMITATIONS, REASONS FOR CAUTION

We have provided no direct demonstration that phagocytic activity is indeed decreased in peritoneal cells from patients with endometriosis or that their endometriotic fluid contains increased amounts of PGE2 when compared with control subjects.

WIDER IMPLICATIONS OF THE FINDINGS

Inhibiting PGE2 signaling, in order to restore or enhance the phagocytic capability of macrophages, may represent a new direction of thinking in developing novel strategies against endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from National Science Council of Taiwan, Republic of China (NSC97-2314-B-006-020-MY3) to M.-H.W. and (NSC98-2320-B-006-026-MY3) to S.-J.T., and grants from the Chang Gung Memorial Hospital, Taiwan, Republic of China (CMRPG891432 and CMRPG8A0531) to P.-C.C. None of the authors have any conflicts of interest.

Hypoxia-induced microRNA-20a expression increases ERK phosphorylation and angiogenic gene expression in endometriotic stromal cells

CONTEXT

Aberrant activation of MAPK has been implicated to play important roles in pathological processes of endometriosis. However, how MAPK are constitutively activated in endometriotic tissues remains largely unknown. microRNA are small noncoding RNA that regulate the stability or translational efficiency of target mRNA by interacting with the 3' untranslated region. Thus, miRNA are thought to be modulators of the transcriptional response, fine-tuning gene expression.

OBJECTIVE

The aim of this study was to evaluate the functional roles of microRNA-20a (miR20a) in MAPK activation and the pathogenesis of endometriosis.

DESIGN

miR20a expression was analyzed in nonpaired (endometrium = 17; endometriosis = 37) and paired (n = 12) endometriotic tissues by quantitative RT-PCR. Overexpression of miR20a in eutopic endometrial stromal cells or inhibition of miR20a in ectopic endometriotic stromal cells was used to evaluate its impact on ERK phosphorylation and subsequently angiogenesis- and proliferation-related gene expression.

RESULTS

Levels of miR20a were up-regulated in endometriotic stromal cells. Elevation of miR20a was up-regulated by hypoxia inducible factor-1α. The up-regulation of miR20a causes the down-regulation of dual-specificity phosphatase-2, which leads to prolonged ERK phosphorylation and an increase in the expression of several angiogenic genes. Furthermore, the up-regulation of miR20a enhances the prostaglandin E(2)-induced expression of fibroblast growth factor-9, a potent mitogen that stimulates both endothelial and endometrial cell proliferation.

CONCLUSION

Our findings provide the novel mechanism that not only functionally links together hypoxic stress, miR20a expression, aberrant ERK phosphorylation, and angiogenesis but also demonstrates that miR20a is an important modulator in the development of endometriosis.

Radiation-induced increase in cell migration and metastatic potential of cervical cancer cells operates via the K-Ras pathway

Radiotherapy is a well established treatment for cervical cancer, the second most common cancer in women worldwide. However, metastasis often circumvents the efficacy of radiotherapy. This study was conducted to elucidate the molecular mechanism of radioresistance-associated metastatic potential of cervical cancer cells. We established three radioresistant cervical cancer cell lines by exposure of cells to a sublethal dose of radiation and screened for lines that exhibited an increased migration phenotype for at least 6 months before undertaking mechanistic studies. Radiation-associated metastatic potential was evaluated using a wound-healing assay, time-lapse recording, and cell locomotion into the lungs of BALB/c nude mice. The radioresistant C33A and CaSki cell lines, but not the radioresistant HeLa cell line, exhibited significantly increased cell migration and wound healing than did wild-type cells. Furthermore, K-Ras played a prometastatic role via the activation of c-Raf/p38, whereas interference of those mediators via either RNA interference-mediated knockdown or the use of chemical inhibitors substantially reversed the radioresistance-associated increase in cell migration. Clinical examination further showed the relative up-regulation of the K-Ras/c-Raf/p38 pathway in locally recurring tumors and distant metastases compared with in the primary cervical tumor. These findings demonstrate that a sublethal dose of radiation can enhance the metastatic potential of human cervical cancer cells via K-Ras/c-Raf/p38 signaling, highlighting the potential development of specific inhibitors for reducing metastatic potential during radiotherapy.

Overexpression of pyruvate dehydrogenase kinase 3 increases drug resistance and early recurrence in colon cancer

The switch of cellular metabolism from mitochondrial respiration to glycolysis is the hallmark of cancer cells and is associated with tumor malignancy. Pyruvate dehydrogenase kinase-1 (PDK1) and PDK3 participate in the metabolic switch of cancer cells; however, the medical significance of PDK1 and PDK3 in cancer progression is not known. Here, we assessed the expression profiles of PDK1 and PDK3 in colorectal cancer. Western blot analysis (n = 74) demonstrated that PDK3 was markedly increased in colon cancer compared to that in adjacent normal tissues, whereas PDK1 was decreased in cancer cells. In addition, PDK3 expression was positively correlated with that of hypoxia inducible factor-1α (HIF-1α) in cancer cells. Further analysis using immunohistochemical staining revealed that PDK3 levels were positively associated with severity of cancer and negatively associated with disease-free survival. In vitro studies using several colon cancer cell lines showed that PDK3 expression was controlled by HIF-1α and contributed to hypoxia-induced increased drug resistance, perhaps explaining why patients with PDK3 overexpression have a greater incidence of treatment failure. Taken together, our findings suggest that PDK3 plays an important role in the metabolic switch and drug resistance of colon cancer and is potentially a novel target for cancer therapy.

FUBP3 interacts with FGF9 3' microsatellite and positively regulates FGF9 translation

A TG microsatellite in the 3'-untranslated region (UTR) of FGF9 mRNA has previously been shown to modulate FGF9 expression. In the present study, we investigate the possible interacting protein that binds to FGF9 3'-UTR UG-repeat and study the mechanism underlying this protein-RNA interaction. We first applied RNA pull-down assays and LC-MS analysis to identify proteins associated with this repetitive sequence. Among the identified proteins, FUBP3 specifically bound to the synthetic (UG)(15) oligoribonucleotide as shown by supershift in RNA-EMSA experiments. The endogenous FGF9 protein was upregulated in response to transient overexpression and downregulated after knockdown of FUBP3 in HEK293 cells. As the relative levels of FGF9 mRNA were similar in these two conditions, and the depletion of FUBP3 had no effect on the turn-over rate of FGF9 mRNA, these data suggested that FUBP3 regulates FGF9 expression at the post-transcriptional level. Further examination using ribosome complex pull-down assay showed overexpression of FUBP3 promotes FGF9 expression. In contrast, polyribosome-associated FGF9 mRNA decreased significantly in FUBP3-knockdown HEK293 cells. Finally, reporter assay suggested a synergistic effect of the (UG)-motif with FUBP3 to fine-tune the expression of FGF9. Altogether, results from this study showed the novel RNA-binding property of FUBP3 and the interaction between FUBP3 and FGF9 3'-UTR UG-repeat promoting FGF9 mRNA translation.

NFAT and CREB regulate Kaposi's sarcoma-associated herpesvirus-induced cyclooxygenase 2 (COX-2)

COX-2 has been implicated in Kaposi's sarcoma-associated herpesvirus (KSHV) latency and pathogenesis (A. George Paul, N. Sharma-Walia, N. Kerur, C. White, and B. Chandran, Cancer Res. 70:3697-3708, 2010; P. P. Naranatt, H. H. Krishnan, S. R. Svojanovsky, C. Bloomer, S. Mathur, and B. Chandran, Cancer Res. 64:72-84, 2004; N. Sharma-Walia, A. G. Paul, V. Bottero, S. Sadagopan, M. V. Veettil, N. Kerur, and B. Chandran, PLoS Pathog. 6:e1000777, 2010; N. Sharma-Walia, H. Raghu, S. Sadagopan, R. Sivakumar, M. V. Veettil, P. P. Naranatt, M. M. Smith, and B. Chandran, J. Virol. 80:6534-6552, 2006). However, the precise regulatory mechanisms involved in COX-2 induction during KSHV infection have never been explored. Here, we identified cis-acting elements involved in the transcriptional regulation of COX-2 upon KSHV de novo infection. Promoter analysis using human COX-2 promoter deletion and mutation reporter constructs revealed that nuclear factor of activated T cells (NFAT) and the cyclic AMP (cAMP) response element (CRE) modulate KSHV-mediated transcriptional regulation of COX-2. Along with multiple KSHV-induced signaling pathways, infection-induced prostaglandin E(2) (PGE(2)) also augmented COX-2 transcription. Infection of endothelial cells markedly induced COX-2 expression via a cyclosporine A-sensitive, calcineurin/NFAT-dependent pathway. KSHV infection increased intracellular cAMP levels and activated protein kinase A (PKA), which phosphorylated the CRE-binding protein (CREB) at serine 133, which probably led to interaction with CRE in the COX-2 promoter, thereby enhancing COX-2 transcription. PKA selective inhibitor H-89 pretreatment strongly inhibited CREB serine 133, indicating the involvement of a cAMP-PKA-CREB-CRE loop in COX-2 transcriptional regulation. In contrast to phosphatidylinositol 3-kinase and protein kinase C, inhibition of FAK and Src effectively reduced KSHV infection-induced COX-2 transcription and protein levels. Collectively, our study indicates that mediation of COX-2 transcription upon KSHV infection is a paradigm of a complex regulatory milieu involving the interplay of multiple signal cascades and transcription factors. Intervention at each step of COX-2/PGE(2) induction can be used as a potential therapeutic target to treat KSHV-associated neoplasm and control inflammatory sequels of KSHV infection.

AUF1 p42 isoform selectively controls both steady-state and PGE2-induced FGF9 mRNA decay

Fibroblast growth factor 9 (FGF9) is an autocrine/paracrine growth factor that plays vital roles in many physiologic processes including embryonic development. Aberrant expression of FGF9 causes human diseases and thus it highlights the importance of controlling FGF9 expression; however, the mechanism responsible for regulation of FGF9 expression is largely unknown. Here, we show the crucial role of an AU-rich element (ARE) in FGF9 3′-untranslated region (UTR) on controlling FGF9 expression. Our data demonstrated that AUF1 binds to this ARE to regulate FGF9 mRNA stability. Overexpression of each isoform of AUF1 (p37, p40, p42 and p45) showed that only the p42 isoform reduced the steady-state FGF9 mRNA. Also, knockdown of p42^AUF1 prolonged the half-life of FGF9 mRNA. The induction of FGF9 mRNA in prostaglandin (PG) E₂-treated human endometrial stromal cells was accompanied with declined cytoplasmic AUF1. Nevertheless, ablation of AUF1 led to sustained elevation of FGF9 expression in these cells. Our study demonstrated that p42^AUF1 regulates both steady-state and PGE₂-induced FGF9 mRNA stability through ARE-mediated mRNA degradation. Since almost half of the FGF family members are ARE-containing genes, our findings also suggest that ARE-mediated mRNA decay is a common pathway to control FGFs expression, and it represents a novel RNA regulon to coordinate FGFs homeostasis in various physiological conditions.

Microarray analysis of equine endometrium at days 8 and 12 of pregnancy

Establishment and maintenance of pregnancy in equids is only partially understood. To provide new insights into early events of this process, we performed a systematic analysis of transcriptome changes in the endometrium at Days 8 and 12 of pregnancy. Endometrial biopsy samples from pregnant and nonpregnant stages were taken from the same mares. Composition of the collected biopsy samples was analyzed using quantitative stereological techniques to determine proportions of surface and glandular epithelium and blood vessels. Microarray analysis did not reveal detectable changes in gene expression at Day 8, whereas at Day 12 of pregnancy 374 differentially expressed genes were identified, 332 with higher and 42 with lower transcript levels in pregnant endometrium. Expression of selected genes was validated by quantitative real-time RT-PCR. Gene set enrichment analysis, functional annotation clustering, and cocitation analysis were performed to characterize the genes differentially expressed in Day 12 pregnant endometrium. Many known estrogen-induced genes and genes involved in regulation of estrogen signaling were found, but also genes known to be regulated by progesterone and prostaglandin E2. Additionally, differential expression of a number of genes related to angiogenesis and vascular remodeling suggests an important role of this process. Furthermore, genes that probably have conserved functions across species, such as CRYAB, ERRFI1, FGF9, IGFBP2, NR2F2, STC1, and TNFSF10, were identified. This study revealed the potential target genes and pathways of conceptus-derived estrogens, progesterone, and prostaglandin E2 in the equine endometrium probably involved in the early events of establishment and maintenance of pregnancy in the mare.

MYEOV (myeloma overexpressed gene) drives colon cancer cell migration and is regulated by PGE2

Introduction

We have previously reported that Myeov (MYEloma OVerexpressed gene) expression is enhanced in colorectal cancer (CRC) and that it promotes CRC cell proliferation and invasion. The role of Myeov in CRC migration is unclear. ProstaglandinE2 (PGE ₂) is a known factor in promoting CRC carcinogenesis. The role of PGE ₂ in modulating Myeov expression has also not been defined.

Aim

To assess the role of Myeov expression in CRC cell migration and to evaluate the role of PGE ₂ in Myeov bioactivity.

Methods

siRNA mediated Myeov knockdown was achieved in T84 CRC cells. Knockdown was assessed using quantitative real time PCR. The effect of knockdown on CRC cell migration was assessed using a scratch wound healing assay. Separately, T84 cells were treated with PGE ₂ (0.00025 μ M, 0.1 μ M and 1 μ M) from 30 min to 3 hours and the effect on Myeov gene expression was assessed using real time PCR.

Results

Myeov knockdown resulted in a significant reduction in CRC cell migration, observable as early as 12 hours (P < 0.05) with a 39% reduction compared to control at 36 hours (p < 0.01). Myeov expression was enhanced after treatment with PGE ₂, with the greatest effect seen at 60 mins for all 3 PGE ₂ doses. This response was dose dependent with a 290%, 550% & 1,000% increase in Myeov expression for 0.00025 μ M, 0.1 μ M and 1 μ M PGE ₂ respectively.

Conclusion

In addition to promoting CRC proliferation and invasion, our findings indicate that Myeov stimulates CRC cell migration, and its expression may be PGE ₂ dependant.

Kaposi's sarcoma associated herpes virus (KSHV) induced COX-2: a key factor in latency, inflammation, angiogenesis, cell survival and invasion

Kaposi's sarcoma (KS), an enigmatic endothelial cell vascular neoplasm, is characterized by the proliferation of spindle shaped endothelial cells, inflammatory cytokines (ICs), growth factors (GFs) and angiogenic factors. KSHV is etiologically linked to KS and expresses its latent genes in KS lesion endothelial cells. Primary infection of human micro vascular endothelial cells (HMVEC-d) results in the establishment of latent infection and reprogramming of host genes, and cyclooxygenase-2 (COX-2) is one of the highly up-regulated genes. Our previous study suggested a role for COX-2 in the establishment and maintenance of KSHV latency. Here, we examined the role of COX-2 in the induction of ICs, GFs, angiogenesis and invasive events occurring during KSHV de novo infection of endothelial cells. A significant amount of COX-2 was detected in KS tissue sections. Telomerase-immortalized human umbilical vein endothelial cells supporting KSHV stable latency (TIVE-LTC) expressed elevated levels of functional COX-2 and microsomal PGE2 synthase (m-PGES), and secreted the predominant eicosanoid inflammatory metabolite PGE2. Infected HMVEC-d and TIVE-LTC cells secreted a variety of ICs, GFs, angiogenic factors and matrix metalloproteinases (MMPs), which were significantly abrogated by COX-2 inhibition either by chemical inhibitors or by siRNA. The ability of these factors to induce tube formation of uninfected endothelial cells was also inhibited. PGE2, secreted early during KSHV infection, profoundly increased the adhesion of uninfected endothelial cells to fibronectin by activating the small G protein Rac1. COX-2 inhibition considerably reduced KSHV latent ORF73 gene expression and survival of TIVE-LTC cells. Collectively, these studies underscore the pivotal role of KSHV induced COX-2/PGE2 in creating KS lesion like microenvironment during de novo infection. Since COX-2 plays multiple roles in KSHV latent gene expression, which themselves are powerful mediators of cytokine induction, anti-apoptosis, cell survival and viral genome maintainence, effective inhibition of COX-2 via well-characterized clinically approved COX-2 inhibitors could potentially be used in treatment to control latent KSHV infection and ameliorate KS.

Kaposi's sarcoma associated herpes virus (KSHV), with a 160 kb DNA genome, has evolved with two distinct life cycle phases, namely latency and lytic replication. KS, a complex angioproliferative disease, is regulated by a balance between pro-angiogenic and anti-angiogenic factors. In our previous study, we showed that KSHV modulates host factors COX-2/PGE2 for its own advantage to promote its latent (persistent) infection. The premise that COX-2 is involved in growth and progression of several types of solid cancers and inflammation associated diseases has been well documented but has never been studied in KS. Here, utilizing COX-2 inhibition strategies, including chemical inhibition and a gene silencing approach, we systematically identified the potential role of KSHV induced COX-2/PGE2 in viral pathogenesis related events such as secretion of inflammatory and angiogenic cytokines, MMPs and cell adhesion in de novo infected or latently infected endothelial cells. We report that COX-2/PGE2 inhibition down-regulates viral latent gene expression and survival of latently infected endothelial cells. The data emanating from our in vitro studies is valuable, informative and requires further examination using an in vitro angiogenic model and in vivo nude mice model to further validate COX-2 as a novel therapeutic to target latent infection and the associated diseases like KS.

Inhibition of CD36-dependent phagocytosis by prostaglandin E2 contributes to the development of endometriosis

Dysfunction in macrophage-mediated phagocytosis of aberrant cells that undergo retrograde transport to the peritoneal cavity is considered an important factor in the development of endometriosis. However, the mechanisms responsible for the loss of function of macrophages remain largely unknown. Herein, we report that prostaglandin (PG) E(2), via the EP2 receptor-dependent signaling pathway, inhibits the expression of CD36 in peritoneal macrophages, resulting in reduced phagocytic ability. PGE(2)-mediated inhibition of macrophage phagocytic capability was restored by ectopic expression of CD36. Treatment with PGE(2) inhibited CD36-dependent phagocytosis of peritoneal macrophages and increased the number and size of endometriotic lesions in mice. In contrast, blockade of PGE(2) production by cyclooxygenase inhibitors enhanced the phagocytic ability of peritoneal macrophages and reduced endometriotic lesion formation. Taken together, our findings reveal a potential mechanism of immune dysfunction during endometriosis development and may contribute to the design of an effective prevention/treatment regimen.

Leptin on peritoneal macrophages of patients with endometriosis

PROBLEM

The expression of cyclooxygenase (COX)-2 is considered as a marker of macrophage activation and has been implicated in the development of endometriosis. Leptin is an immunomodulator, which may also affect the development of endometriosis. However, how leptin contributes to these pathological processes has not been completely understood. The aim of this study was to investigate the effects of leptin on peritoneal macrophages and its relationship with endometriosis.

METHODS OF STUDY

Peritoneal fluid from 60 women of reproductive age was obtained while they underwent laparoscopy. Forty patients had endometriosis and 20 patients did not have endometriosis. The concentration of leptin in the peritoneal fluid and prostaglandin F(2alpha) levels was measured by ELISA, and the other protein expression using Western blot when peritoneal macrophages were stimulated with leptin.

RESULTS

Concentration of leptin in peritoneal fluid was increased in patients with endometriosis compared with disease-free normal control. Functional leptin receptor was present in peritoneal macrophages. Treatment of peritoneal macrophages with leptin induced COX-2 expression. Production of prostaglandin F(2alpha) by peritoneal macrophages was increased after leptin stimulation in women with endometriosis.

CONCLUSION

Elevated concentration of leptin in peritoneal fluid may contribute to the pathological process of endometriosis through activation of peritoneal macrophages.

PKA, Rap1, ERK1/2, and p90RSK mediate PGE2 and EP4 signaling in neonatal ventricular myocytes

We have previously reported that 1) inhibition of cyclooxygenase-2 and PGE(2) production reduces hypertrophy after myocardial infarction in mice and 2) PGE(2) acting through its EP4 receptor causes hypertrophy of neonatal ventricular myocytes (NVMs) via ERK1/2. It is known that EP4 couples to adenylate cyclase, cAMP, and PKA. The present study was designed to determine interactions between the cAMP-PKA pathway and ERK1/2 and to further characterize events downstream of ERK1/2. We hypothesized that PKA and the small GTPase Rap are upstream of ERK1/2 and that 90-kDa ribosomal S6 kinase (p90RSK) is activated downstream. Treatment of NVMs with PGE(2) activated Rap, and this activation was inhibited in part by an EP4 antagonist and PKA inhibition. Transfection of a dominant negative mutant of Rap reduced PGE(2) activation of ERK1/2. PGE(2) activation of p90RSK was also dependent on EP4, PKA, and Rap. We also tested the involvement of Rap, ERK1/2, and p90RSK in PGE(2) regulation of gene expression. PGE(2) stimulation of brain natriuretic peptide promoter activity was blocked by either ERK1/2 inhibition or a dominant negative mutation of p90RSK. PGE(2) stimulation of c-Fos was dependent on EP4, PKA, ERK1/2, and p90RSK, whereas only the latter two kinases were involved in PGE(2) regulation of early growth response-1. Finally, we tested the involvement of EP4-dependent signaling in the NVM growth response and found that the overexpression of EP4 increased NVM cell size. We conclude that EP4-dependent signaling in NVMs in part involves PKA, Rap, ERK1/2, and p90RSK and results in the increased expression of brain natriuretic peptide and c-Fos.

EP(3) prostanoid receptor isoforms utilize distinct mechanisms to regulate ERK 1/2 activation

Prostaglandin-E(2) (PGE(2)) is a hormone derived from the metabolism of arachidonic acid whose functions include regulation of platelet aggregation, fever and smooth muscle contraction/relaxation. PGE(2) mediates its physiological and pathophysiological effects through its binding to four G-protein coupled receptor subtypes, named EP(1), EP(2), EP(3) and EP(4). The EP(3) prostanoid receptor is unique in that it has multiple isoforms generated by alternative mRNA splicing. These splice variants display differences in tissue expression, constitutive activity and regulation of signaling molecules. To date there are few reports identifying differential activities of EP(3) receptor isoforms and their effects on gene regulation. We generated HEK cell lines expressing the human EP(3-Ia), EP(3-II) or EP(3-III) isoforms. Using immunoblot analysis we found that nM concentrations of PGE(2) strongly stimulated the phosphorylation of ERK 1/2 by the EP(3-II) and EP(3-III) isoforms; whereas, ERK 1/2 phosphorylation by the EP(3-Ia) isoform was minimal and only occurred at muM concentrations of PGE(2). Furthermore, the mechanisms of the PGE(2) mediated phosphorylation of ERK 1/2 by the EP(3-II) and EP(3-III) isoforms were different. Thus, PGE(2) stimulation of ERK 1/2 phosphorylation by the EP(3-III) isoform involves activation of a Galpha(i)/PI3K/PKC/Src and EGFR-dependent pathway; while for the EP(3-II) isoform it involves activation of a Galpha(i)/Src and EGFR-dependent pathway. These differences result in unique differences in the regulation of reporter plasmid activity for the downstream effectors ELK1 and AP-1 by the EP(3-II) and EP(3-III) prostanoid receptor isoforms.

Suppression of prostaglandin E2-induced MUC5AC overproduction by RGS4 in the airway

The mechanism by which E-prostanoid (EP) receptor is critically involved in PGE(2)-induced mucin 5AC (MUC5AC) gene expression in the airway has been unclear. Furthermore, there have been little reports regarding the negative regulatory mechanism and/or proteins that affect PGE(2)-induced MUC5AC overproduction. In the present study, we found that PGE(2) induced MUC5AC gene expression in a dose-dependent manner (EC(50): 73.31 +/- 3.13 nM) and that the EP(2/4)-specific agonist, misoprostol, increased MUC5AC mRNA level, whereas the EP(1/3)-specific agonist, sulprostone, had no effect. Interestingly, the cAMP concentration (685.1 +/- 14.9 pM) of the EC(50) value of EP(4)-mediated cAMP production was much higher than that of EP(2) (462.33 +/- 23.79 pM), suggesting that EP(4) has higher sensitivity to PGE(2) compared with EP(2). Moreover, PGE(2)-induced Muc5ac overproduction was much increased in regulator of G protein signaling (Rgs) 4 knockout (KO) mice compared with wild-type mice at both transcriptional and translational levels, and it was dramatically suppressed in Rgs4 KO mice that had been infected with lentivirus expressing RGS4 (lenti::RGS4) compared with lentivirus expressing enhanced green fluorescent protein (lenti::eGFP). Finally, we demonstrate that PGE(2) can induce MUC5AC overproduction via the EP(4) receptor and that RGS4 may have suppressive effects in controlling MUC5AC overexpression in the airway. These findings may provide a molecular paradigm for the development of novel drugs for respiratory diseases.

Induction of pyruvate dehydrogenase kinase-3 by hypoxia-inducible factor-1 promotes metabolic switch and drug resistance

The switch of cellular metabolism from mitochondrial respiration to glycolysis is the hallmark of cancer cells and associated with tumor malignancy. However, the mechanism of this metabolic switch remains largely unknown. Herein, we reported that hypoxia-inducible factor-1 (HIF-1) induced pyruvate dehydrogenase kinase-3 (PDK3) expression leading to inhibition of mitochondrial respiration. Promoter activity assay, small interference RNA knockdown assay, and chromatin immunoprecipitation assay demonstrated that hypoxia-induced PDK3 gene activity was regulated by HIF-1 at the transcriptional level. Forced expression of PDK3 in cancer cells resulted in increased lactic acid accumulation and drugs resistance, whereas knocking down PDK3 inhibited hypoxia-induced cytoplasmic glycolysis and cell survival. These data demonstrated that increased PDK3 expression due to elevated HIF-1alpha in cancer cells may play critical roles in metabolic switch during cancer progression and chemoresistance in cancer therapy.