A novel angiogenic role for prostaglandin F2alpha-FP receptor interaction in human endometrial adenocarcinomas

Aldo-keto reductase family member C3 (AKR1C3) promotes hepatocellular carcinoma cell growth by producing prostaglandin F2α

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Current therapies are effective for HCC patients with early disease, but many patients suffer recurrence after surgery and have a poor response to chemotherapy. Therefore, new therapeutic targets are needed. We analyzed gene expression profiles between HCC tissues and normal adjacent tissues from public databases and found that the expression of genes involved in lipid metabolism was significantly different. The analysis showed that AKR1C3 was upregulated in tumors, and high AKR1C3 expression was associated with a poorer prognosis in HCC patients. In vitro, assays demonstrated that the knockdown of AKR1C3 or the addition of the AKR1C3 inhibitor indomethacin suppressed the growth and colony formation of HCC cell lines. Knockdown of AKR1C3 in Huh7 cells reduced tumor growth in vivo. To explore the mechanism, we performed pathway enrichment analysis, and the results linked the expression of AKR1C3 with prostaglandin F2 alpha (PGF2α) downstream target genes. Suppression of AKR1C3 activity reduced the production of PGF2α, and supplementation with PGF2α restored the growth of indomethacin-treated Huh7 cells. Knockdown of the PGF receptor (PTGFR) and treatment with a PTGFR inhibitor significantly reduced HCC growth. We showed that indomethacin potentiated the sensitivity of Huh7 cells to sorafenib. In summary, our results indicate that AKR1C3 upregulation may promote HCC growth by promoting the production of PGF2α, and suppression of PTGFR limited HCC growth. Therefore, targeting the AKR1C3-PGF2α-PTGFR axis may be a new strategy for the treatment of HCC.

Prostaglandin F2α synthase promotes oxaliplatin resistance in colorectal cancer through prostaglandin F2α-dependent and F2α-independent mechanism

BACKGROUND

Oxaliplatin (Oxa) is the first-line chemotherapy drug for colorectal cancer (CRC), and Oxa resistance is crucial for treatment failure. Prostaglandin F2α synthase (PGF2α) (PGFS), an enzyme that catalyzes the production of PGF2α, is involved in the proliferation and growth of a variety of tumors. However, the role of PGFS in Oxa resistance in CRC remains unclear.

AIM

To explore the role and related mechanisms of PGFS in mediating Oxa resistance in CRC.

METHODS

The PGFS expression level was examined in 37 pairs of CRC tissues and paracancerous tissues at both the mRNA and protein levels. Overexpression or knockdown of PGFS was performed in CRC cell lines with acquired Oxa resistance (HCT116-OxR and HCT8-OxR) and their parental cell lines (HCT116 and HCT8) to assess its influence on cell proliferation, chemoresistance, apoptosis, and DNA damage. For determination of the underlying mechanisms, CRC cells were examined for platinum-DNA adducts and reactive oxygen species (ROS) levels in the presence of a PGFS inhibitor or its products.

RESULTS

Both the protein and mRNA levels of PGFS were increased in the 37 examined CRC tissues compared to the adjacent normal tissues. Oxa induced PGFS expression in the parental HCT116 and HCT8 cells in a dose-dependent manner. Furthermore, overexpression of PGFS in parental CRC cells significantly attenuated Oxa-induced proliferative suppression, apoptosis, and DNA damage. In contrast, knockdown of PGFS in Oxa-resistant HCT116 and HCT8 cells (HCT116-OxR and HCT8-OxR) accentuated the effect of Oxa treatment in vitro and in vivo. The addition of the PGFS inhibitor indomethacin enhanced the cytotoxicity caused by Oxa. Treatment with the PGFS-catalyzed product PGF2α reversed the effect of PGFS knockdown on Oxa sensitivity. Interestingly, PGFS inhibited the formation of platinum-DNA adducts in a PGF2α-independent manner. PGF2α exerts its protective effect against DNA damage by reducing ROS levels.

CONCLUSION

PGFS promotes resistance to Oxa in CRC via both PGF2α-dependent and PGF2α-independent mechanisms.

Lipid metabolism and endometrial receptivity

BACKGROUND

Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms, especially the roles of lipid metabolism in endometrial receptivity, remain largely elusive.

OBJECTIVE AND RATIONALE

This review summarizes current evidence on the impacts of several major lipids and lipid-derived mediators on the embryonic implantation process. Emerging methods for evaluating endometrial receptivity, for example transcriptomic and lipidomic analysis, are also discussed.

SEARCH METHODS

The PubMed and Embase databases were searched using the following keywords: (lipid or fatty acid or prostaglandin or phospholipid or sphingolipid or endocannabinoid or lysophosphatidic acid or cholesterol or progesterone or estrogen or transcriptomic or lipidomic or obesity or dyslipidemia or polycystic ovary syndrome) AND (endometrial receptivity or uterine receptivity or embryo implantation or assisted reproductive technology or in vitro fertilization or embryo transfer). A comprehensive literature search was performed on the roles of lipid-related metabolic pathways in embryo implantation published between January 1970 and March 2022. Only studies with original data and reviews published in English were included in this review. Additional information was obtained from references cited in the articles resulting from the literature search.

OUTCOMES

Recent studies have shown that a fatty acids-related pro-inflammatory response in the embryo-endometrium boundary facilitates pregnancy via mediation of prostaglandin signaling. Phospholipid-derived mediators, for example endocannabinoids, lysophosphatidic acid and sphingosine-1-phosphate, are associated with endometrial receptivity, embryo spacing and decidualization based on evidence from both animal and human studies. Progesterone and estrogen are two cholesterol-derived steroid hormones that synergistically mediate the structural and functional alterations in the uterus ready for blastocyst implantation. Variations in serum cholesterol profiles throughout the menstrual cycle imply a demand for steroidogenesis at the time of window of implantation (WOI). Since 2002, endometrial transcriptomic analysis has been serving as a diagnostic tool for WOI dating. Numerous genes that govern lipid homeostasis have been identified and, based on specific alterations of lipidomic signatures differentially expressed in WOI, lipidomic analysis of endometrial fluid provides a possibility for non-invasive diagnosis of lipids alterations during the WOI.

WIDER IMPLICATIONS

Given that lipid metabolic dysregulation potentially plays a role in infertility, a better understanding of lipid metabolism could have significant clinical implications for the diagnosis and treatment of female reproductive disorders.

Prostaglandin F2 and EP2 Agonists Exert Different Effects on 3D 3T3-L1 Spheroids during Their Culture Phase

To elucidate the effects of switching a PGF2α agonist, bimatoprost acid (BIM-A), to an EP2 agonist (Omidenepag—OMD; butaprost—Buta) or reversing the switching on adipose tissue, two-dimensional (2D) and three-dimensional (3D) cultures of 3T3-L1 cells were analyzed by lipid staining and according to the mRNA expression of adipogenesis-related genes (Pparγ, Ap2, and Leptin), components of the extracellular matrix (ECM; collagen1 (Col1), Col4, Col6, and fibronectin (Fn)), and the sizes and stiffness of the 3D spheroids. Switching from BIM-A to EP2 agonists caused (1) suppression of lipid staining and downregulation of most adipogenesis-related genes, (2) smaller and stiffer 3D spheroids, and (3) upregulation of Col1 and Fn, downregulation of Col4 (2D), or up-regulation of all ECM genes (3D, BIM-A to OMD), as well as downregulation of Col6 (3D, BIM-A to Buta). In contrast, reversing the switching resulted in (1) an enhancement in lipid staining (2D) and a significant upregulation of adipogenesis-related genes (2D, 3D Buta to BIM-A), (2) larger and slightly stiffer 3D spheroids, and (3) upregulation of Col1 and Fn (2D). These collective findings indicate that the switching orders of BIM-A and EP2 agonists have a significant effect on lipid metabolism, ECM expression, and the physical stiffness of 3T3-L1 cells.

The Effect of Intraocular Pressure-Lowering Medication on Metastatic Uveal Melanomas

Simple Summary

The most lethal tumor in the eye is metastatic uveal melanomas, while the most common cause of irreversible blindness is glaucoma. Glaucoma is treated by prescribing intraocular pressure-lowering drugs. Theoretically, these drugs may affect the risk of metastasis of intraocular tumors (uveal melanomas). Using data of a long-running and ongoing study on uveal melanomas, we found that eye drops that lower the intraocular pressure by stimulating outflow of fluid (aqueous humor) may increase the risk of metastasis, and subsequent mortality. Therefore, in patients at risk or suspect for uveal melanoma, we recommend choosing ophthalmic drugs with a working mechanism that is not based on the increase of outflow of aqueous humor from the eye.

Abstract

Background: There has been speculation that IOP-lowering medication, which increases aqueous humor outflow, increases the risk of metastatic uveal melanoma (UM). This hypothesis has not been studied previously but is relevant for UM patients who use IOP-lowering medication. The aim of the current study is to assess the association between the use of intraocular pressure (IOP)-lowering medication and the risk of metastatic UM, and mortality. Methods: A retrospective cohort study, in which patients from the Rotterdam Ocular Melanoma Study were included from 1986 onwards. Medical records were evaluated for use of IOP-lowering medication at baseline (i.e., before diagnosis). For each IOP-lowering medication, we divided patients into two groups for comparison (e.g., patients with alpha2-agonist use and patients without alpha2-agonist use). All patients underwent regular ophthalmic examinations and routine screening for metastasis. Survival analyses were initiated to compare groups in each IOP-lowering medication group. In addition, secondary analyses were performed to examine the association between IOP and the development of metastatic UM, and mortality. Results: A total of 707 patients were included of whom 13 patients used prostaglandin or pilocarpine at baseline. For alpha2-agonist, beta-blocker, carbonic anhydrase inhibitor, and oral IOP-lowering medication these were 4, 14, 11, and 12 patients, respectively. The risk of metastatic UM (choroid and ciliary body melanoma) among the prostaglandin/pilocarpine users was significantly higher than controls (HR [95% CI]: 4.840 [1.452–16.133]). Mortality did not differ significantly among the IOP-lowering medications groups, except for the prostaglandin or pilocarpine group (HR [95% CI]: 7.528 [1.836–30.867]). If we combined all IOP-lowering medication that increase aqueous humor outflow, the risk (HR [95% CI]) of metastatic UM and mortality was 6.344 (1.615–24.918) and 9.743 (2.475–38.353), respectively. There was an association between IOP and mortality, but not for the onset of metastatic UM. Conclusion: The use of topical prostaglandin or pilocarpine may increase the risk of metastatic UM and mortality compared to patients without prostaglandin or pilocarpine use. Therefore, use of IOP-lowering medication which increases aqueous humor outflow, should be avoided in patients with (presumed) UM.

Addition of EP2 agonists to an FP agonist additively and synergistically modulates adipogenesis and the physical properties of 3D 3T3-L1 sphenoids

The additive effects of prostaglandin (PG)-EP2 agonists on a PG-FP agonist toward adipogenesis in two- or three-dimension (2D or 3D) cultures of 3T3-L1 cells was examined by lipid staining, the mRNA expression of adipogenesis related genes, and extracellular matrixes (ECMs) including collagen molecules (Col) -1, -4 and -6, and fibronectin (Fn), and the sizes and physical properties of 3D sphenoids, as measured by a micro-squeezer. The results indicate that adipogenesis induced 1) an enlargement in the sizes of 3D sphenoids, 2) a substantial enhancement in lipid staining, the expression of the PParγ, Ap2 and Leptin genes, and 3) a significant decrease in the stiffness of the 3D sphenoids. These effects were inhibited by bimatoprost acid (BIM-A), but 4) adipogenesis induced significant down-regulation of Col1 and Fn, and the significant up-regulation of the Col4 and Col6 genes were unchanged by BIM-A. On the addition of an EP2 agonist, such as omidenepag (OMD) or butaprost (Buta), to BIM-A, 1) the sizes of the 3D sphenoids were further decreased, 2) lipid staining was decreased (2D; OMD, 3D; Buta) 3) the stiffness of the 3D sphenoids was increased by Buta, 4) the expression of PParγ was up-regulated (2D; Buta) or unchanged (3D), the expression of Ap2 was down-regulated (2D; OMD) or up-regulated (3D; Buta), and the expression of Leptin was increased (2D), 5) the expression of all four (OMD) or all except Col4 (buta) in 2D, and Col1and Col4 (OMD) in 3D were up-regulated. These collective findings indicate that the addition of an EP2 agonist, OMD or Buta significantly modulated the BIM-A induced suppression of adipogenesis as well as physical properties of 2D and 3D cultured 3T3-L1 cells in different manners.

Omidenepag, a Selective, Prostanoid EP2 Agonist, Does Not Suppress Adipogenesis in 3D Organoids of Human Orbital Fibroblasts

Purpose

The purpose of this study was to present the effects of the prostanoid EP2 agonist, omidenepag (OMD) on human orbital fibroblasts (HOFs) using a three-dimension (3D) cell culture.

Methods

During adipogenesis of 3D HOFs organoids, changes in size, lipids staining, mRNA expression of adipogenesis related genes, PPARγ, AP2, and ADIPOQ, and extracellular matrix, collagen 1 (COL 1), COL 4, COL 6, and fibronectin (FN), and stiffness by a micro-squeezer were examined in the presence and absence of either 100 nM bimatoprost acid (BIM-A) or 10, 100, or 10,000 nM OMD.

Results

The size of the 3D organoids increased dramatically during adipogenesis, and these were further enhanced in the presence of OMD in contrast to the BIM-A induced suppression effect. The intensity of lipid staining and the mRNA expression of PPARγ were significantly increased upon adipogenesis, and both or latter was markedly inhibited in the presence of OMD or BIM-A, respectively. AP2 expression was also upregulated by adipogenesis, and was further enhanced by BIM-A. The adipogenesis-induced downregulation of COL 1 and FN, or the upregulation of the expression of COL 4 and COL 6 were all suppressed in the presence of BIM-A. In contrast, OMD caused similar effects on COL 4, COL 6, or FN expression, but caused a significant increase in COL 1 expression. Stiffness was significantly increased upon adipogenesis, and was further increased or substantially decreased by BIM-A or OMD, respectively.

Conclusions

The present study indicates that the FP2 agonist, OMD, had different effects on 3D HOFs organoids, as compared to BIM-A.

Translational Relevance

The current study suggests that OMD may not induce deepening of upper eyelid sulcus (DUES).

Effects of topical prostaglandin drops on angiogenesis in an in ovo chick chorioallantoic membrane model

BACKGROUND

To investigate the effects of bimatoprost, latanoprost and travoprost on angiogenesis in the chick chorioallantoic membrane (CAM) model in ovo.

MATERIALS AND METHODS

Fifty fertilized specific-pathogen-free chick eggs were used in this preclinical, prospective, experimental embryo study. Eggs were randomly distributed into 5 groups of ten eggs. Eggs were placed in the incubator after disinfection of their shells with alcohol and monitored appropriate temperature and humidity. On the 3rd day of incubation, a small window was opened on the eggshell. Bimatoprost in group 1, latanoprost in group 2, travoprost in group 3, bevacizumab in group 4, phosphate-buffered-saline (PBS) used in group 5 was applied by injection to CAM. The sterile film was glued onto the broken part of the shell and the eggs were placed in the incubator again. On the 8th day of incubation, eggs were opened and vascular structures on CAMs were examined. Digital photographs were taken, analysed in the ImageJ open source image processing software and differences between groups were evaluated. Thereafter, VEGF (Vascular endothelial growth factor) levels were measured appropriately in the embryo samples.

RESULTS

All embryos in the prostaglandin groups and the PBS control group were observed to have life signs confirmed by heart rate. In 8 embryos in the bevacizumab group, no life signs were confirmed, while 2 embryos with life signs showed severe hypoplasia. Vascular density, number of vessels and VEGF levels in the bimatoprost, latanoprost and travoprost groups, there were statistically significantly higher than the PBS control group.

CONCLUSION

This study demonstrates that topical prostaglandin drops increase angiogenesis in the chick CAM model in ovo.

Effect of Prostanoids on Human Platelet Function: An Overview

Prostanoids are bioactive lipid mediators and take part in many physiological and pathophysiological processes in practically every organ, tissue and cell, including the vascular, renal, gastrointestinal and reproductive systems. In this review, we focus on their influence on platelets, which are key elements in thrombosis and hemostasis. The function of platelets is influenced by mediators in the blood and the vascular wall. Activated platelets aggregate and release bioactive substances, thereby activating further neighbored platelets, which finally can lead to the formation of thrombi. Prostanoids regulate the function of blood platelets by both activating or inhibiting and so are involved in hemostasis. Each prostanoid has a unique activity profile and, thus, a specific profile of action. This article reviews the effects of the following prostanoids: prostaglandin-D₂ (PGD₂), prostaglandin-E₁, -E₂ and E₃ (PGE₁, PGE₂, PGE₃), prostaglandin F_2α (PGF_2α), prostacyclin (PGI₂) and thromboxane-A₂ (TXA₂) on platelet activation and aggregation via their respective receptors.

The Role of Eicosanoids in Gynecological Malignancies

Eicosanoids, bio-active lipid molecules, evoke a multitude of biological effects that directly affect cancer cells and indirectly affect tumor microenvironment. An emerging role has been shown for eicosanoids in the pathogenesis of gynecological malignancies which include cancers of the vulva, vagina, cervix, uterine, and ovary. Eicosanoid biosynthesis pathways start at the metabolism of phospholipids by phospholipase A2 then proceeding to one of three pathways: the cyclooxygenase (COX), lipoxygenase (LOX), or P450 epoxygenase pathways. The most studied eicosanoid pathways include COX and LOX; however, more evidence is appearing to support further study of the P450 epoxygenase pathway in gynecologic cancers. In this review, we present the current knowledge of the role of COX, LOX and P450 pathways in the pathogenesis of gynecologic malignancies. Vulvar and vaginal cancer, the rarest subtypes, there is association of COX-2 expression with poor disease specific survival in vulvar cancer and, in vaginal cancer, COX-2 expression has been found to play a role in mucosal inflammation leading to disease susceptibility and transmission. Cervical cancer is associated with COX-2 levels 7.4 times higher than in healthy tissues. Additionally, HPV elevates COX-2 levels through the EGFR pathway and HIV promotes elevated COX-2 levels in cervical tissue as well as increases PGE2 levels eliciting inflammation and progression of cancer. Evidence supports significant roles for both the LOX and COX pathways in uterine cancer. In endometrial cancer, there is increased expression of 5-LOX which is associated with adverse outcomes. Prostanoids in the COX pathway PGE2 and PGF2α have been shown to play a significant role in uterine cancer including alteration of proliferation, adhesion, migration, invasion, angiogenesis, and the inflammatory microenvironment. The most studied gynecological malignancy in regard to the potential role of eicosanoids in tumorigenesis is ovarian cancer in which all three pathways have shown to be associated or play a role in ovarian tumorigenesis directly on the tumor cell or through modulation of the tumor microenvironment. By identifying the gaps in knowledge, additional pathways and targets could be identified in order to obtain a better understanding of eicosanoid signaling in gynecological malignancies and identify potential new therapeutic approaches.

Bioactive lipids, inflammation and chronic diseases

Endogenous bioactive lipids are part of a complex network that modulates a plethora of cellular and molecular processes involved in health and disease, of which inflammation represents one of the most prominent examples. Inflammation serves as a well-conserved defence mechanism, triggered in the event of chemical, mechanical or microbial damage, that is meant to eradicate the source of damage and restore tissue function. However, excessive inflammatory signals, or impairment of pro-resolving/anti-inflammatory pathways leads to chronic inflammation, which is a hallmark of chronic pathologies. All main classes of endogenous bioactive lipids - namely eicosanoids, specialized pro-resolving lipid mediators, lysoglycerophopsholipids and endocannabinoids - have been consistently involved in the chronic inflammation that characterises pathologies such as cancer, diabetes, atherosclerosis, asthma, as well as autoimmune and neurodegenerative disorders and inflammatory bowel diseases. This review gathers the current knowledge concerning the involvement of endogenous bioactive lipids in the pathogenic processes of chronic inflammatory pathologies.

Prostaglandin F2α stimulates angiogenesis at the embryo-maternal interface during early pregnancy in the pig

Blood vessel formation is a critical process for successful pregnancy establishment and placenta formation. Angiogenic factors such as vascular endothelial growth factor (VEGF), angiopoietins (ANGPTs) or fibroblast growth factor 2 (FGF2) are known to be involved in angiogenesis. However, the mechanism regulating their expression in the porcine endometrium and trophoblast has not been described during early pregnancy establishment. Recently, we reported an important role for prostaglandin F2α (PGF2α) in supporting processes accompanying the peri-implantation period in the pig. The aim of the present study was to determine the effect of PGF2α on angiogenic factor gene and protein expression at the embryo-maternal interface and on capillary-like structure formation by endometrial endothelial cells. In the present study, we used various in vitro models involving endometrial tissue explants, primary porcine trophoblast and endometrial endothelial cells, as well as a swine umbilical vein endothelial cell line (G1410). ANGPT1, ANGPT2 and FGF2 gene expression was analyzed in porcine endometrial explants and in primary trophoblast cells incubated with PGF2α (100 nM, 1 μM). VEGFA gene expression and protein secretion by porcine primary trophoblast cells were studied in vitro using primary trophoblast cells. A network formation assay using the G1410 cell line and primary endothelial cells of endometrial origin was performed to assess the effect of PGF2α on capillary-like structure formation. We found that PGF2α stimulated VEGFA gene expression (1 μM) and secretion of this protein (100 nM) by porcine trophoblast cells (P < 0.05). In endometrial explants, PGF2α increased the expression of the ANGPT1, ANGPT2 and FGF2 genes (P < 0.05). PGF2α stimulated the formation of capillary-like structures acting on porcine endometrial endothelial cells on days 15 and 20 of pregnancy and in the G1410 cell line (P < 0.05). PGF2α-stimulated endothelial cell network formation was diminished by using a MEK kinase inhibitor in G1410 cells. Our results indicate an important role for PGF2α in the regulation of angiogenesis at the embryo-maternal interface. PGF2α promotes angiogenesis in the porcine endometrium by activating the MAPK signaling pathway. The stimulating effect of PGF2α on the formation of capillary-like structures by endothelial cells, together with our previous findings, supports the hypothesis that PGF2α is an important factor promoting the development of the placenta during early pregnancy in the pig.

Inhibition of mPGES-1 or COX-2 Results in Different Proteomic and Lipidomic Profiles in A549 Lung Cancer Cells

Pharmacological inhibition of microsomal prostaglandin E synthase (mPGES)-1 for selective reduction in prostaglandin E₂ (PGE₂) biosynthesis is protective in experimental models of cancer and inflammation. Targeting mPGES-1 is envisioned as a safer alternative to traditional non-steroidal anti-inflammatory drugs (NSAIDs). Herein, we compared the effects of mPGES-1 inhibitor Compound III (CIII) with the cyclooxygenase (COX)-2 inhibitor NS-398 on protein and lipid profiles in interleukin (IL)-1β-induced A549 lung cancer cells using mass spectrometry. Inhibition of mPGES-1 decreased PGE₂ production and increased PGF_2α and thromboxane B₂ (TXB₂) formation, while inhibition of COX-2 decreased the production of all three prostanoids. Our proteomics results revealed that CIII downregulated multiple canonical pathways including eIF2, eIF4/P70S6K, and mTOR signaling, compared to NS-398 that activated these pathways. Moreover, pathway analysis predicted that CIII increased cell death of cancer cells (Z = 3.8, p = 5.1E-41) while NS-398 decreased the same function (Z = -5.0, p = 6.5E-35). In our lipidomics analyses, we found alterations in nine phospholipids between the two inhibitors, with a stronger alteration in the lysophospholipid (LPC) profile with NS-398 compared to CIII. Inhibition of mPGES-1 increased the concentration of sphinganine and dihydroceramide (C_16:0DhCer), while inhibition of COX-2 caused a general decrease in most ceramides, again suggesting different effects on cell death between the two inhibitors. We showed that CIII decreased proliferation and potentiated the cytotoxic effect of the cytostatic drugs cisplatin, etoposide, and vincristine when investigated in a live cell imaging system. Our results demonstrate differences in protein and lipid profiles after inhibition of mPGES-1 or COX-2 with important implications on the therapeutic potential of mPGES-1 inhibitors as adjuvant treatment in cancer. We encourage further investigations to illuminate the clinical benefit of mPGES-1 inhibitors in cancer.

Triumph and tumult of matrix metalloproteinases and their crosstalk with eicosanoids in cancer

Cancer development and metastasis are associated to perturbation in metabolic functions of tumor cells and surrounding inflammatory and stromal cell responses. Eicosanoids and lipid mediators, in this regard, attract potential attention during cancer development. Eicosanoids, which include prostaglandin, prostacyclin, thromboxane, and leukotriene, are synthesized from arachidonic acid when cells are stimulated by stress, cytokines, or other growth factors. However, the underlying mechanism of eicosanoids in cancer development, specially their interactions with proto-oncogene factors in tumor microenvironment, remain unexplored. On the other hand, matrix metalloproteinases (MMPs) are a group of zinc-dependent endopeptidases which are involved in degradation of different extracellular matrix (ECM) proteins. MMPs are associated with different physiological responses, including embryogenesis, vasculogenesis, and cellular remodeling, as well as different disease pathogenesis. Induced MMP responses are especially associated with cancer metastasis and secondary tumor development through proteolytic cleavage of several ECM and non-ECM proteins. Although both eicosanoids and MMPs are involved with cancer progression and metastasis, the interrelation between these two molecules are less explored. The present review discusses relevant studies that connect eicosanoids and MMPs and highlight the crosstalk between them offering novel therapeutic approach in cancer treatment.

Integrated eicosanoid lipidomics and gene expression reveal decreased prostaglandin catabolism and increased 5-lipoxygenase expression in aggressive subtypes of endometrial cancer

Eicosanoids comprise a diverse group of bioactive lipids which orchestrate inflammation, immunity, and tissue homeostasis, and whose dysregulation has been implicated in carcinogenesis. Among the various eicosanoid metabolic pathways, studies of their role in endometrial cancer (EC) have very much been confined to the COX-2 pathway. This study aimed to determine changes in epithelial eicosanoid metabolic gene expression in endometrial carcinogenesis; to integrate these with eicosanoid profiles in matched clinical specimens; and, finally, to investigate the prognostic value of candidate eicosanoid metabolic enzymes. Eicosanoids and related mediators were profiled using liquid chromatography-tandem mass spectrometry in fresh frozen normal, hyperplastic, and cancerous (types I and II) endometrial specimens (n = 192). Sample-matched epithelia were isolated by laser capture microdissection and whole genome expression analysis was performed using microarrays. Integration of eicosanoid and gene expression data showed that the accepted paradigm of increased COX-2-mediated prostaglandin production does not apply in EC carcinogenesis. Instead, there was evidence for decreased PGE₂ /PGF_2α inactivation via 15-hydroxyprostaglandin dehydrogenase (HPGD) in type II ECs. Increased expression of 5-lipoxygenase (ALOX5) mRNA was also identified in type II ECs, together with proportional increases in its product, 5-hydroxyeicosatetraenoic acid (5-HETE). Decreased HPGD and elevated ALOX5 mRNA expression were associated with adverse outcome, which was confirmed by immunohistochemical tissue microarray analysis of an independent series of EC specimens (n = 419). While neither COX-1 nor COX-2 protein expression had prognostic value, low HPGD combined with high ALOX5 expression was associated with the worst overall and progression-free survival. These findings highlight HPGD and ALOX5 as potential therapeutic targets in aggressive EC subtypes. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Overexpression of AKR1C3 significantly enhances human prostate cancer cells resistance to radiation

Aldo-keto reductase 1C3(AKR1C3) is an enzyme involved in prostaglandins metabolism. Studies suggest that AKR1C3 has a pivotal role in the radioresistance of esophageal cancer and non-small-cell lung cancer, yet the role of AKR1C3 in prostate cancer cells radiation resistance has not yet been clarified. In our study, we established a stable overexpressing AKR1C3 cell line (AKR1C3-over) derived from the prostate cell line DU145 and its control cell line (Control). We conducted colony formation assay to determine the role of AKR1C3 in radioresistance and we used its chemical inhibitor to detect whether it can restored the sensitivity of the acquired tumor cells. Flow cytometry assay was carried out to detect IR-induced ROS accumulation. Elisa was adopted to dedect the concentration of PGF2α in the suspension of the cells after 6GY radiation. Western blotting was used to dedect the MAPK and PPAR γ. The results demonstrated that overexpression of AKR1C3 in prostate cancer can result in radioresistance and suppression of AKR1C3 via its chemical inhibitor indocin restored the sensitivity of the acquired tumor cells. According to the flow cytometry assay, ROS was decreased by 80% in DU145-over cells. Also overexpression of AKR1C3 could result in the accumulation of prostaglandin F2α (PGF2α), which can not only promote prostate cancer cell 's proliferation but also could enhance prostate cancer cells resistance to radiation and activated the MAPK pathway and inhibited the expression of PPARγ. In conclusion, we found that overexpression of AKR1C3 significantly enhanced human prostate cancer cells resistance to radiation through activation of MAPK pathway.

Genetic variation in the eicosanoid pathway is associated with non-small-cell lung cancer (NSCLC) survival

Globally, lung cancer results in more deaths worldwide than any other cancer, indicating a need for better treatments. Members of the eicosanoid metabolism pathway represent promising therapeutic targets, as several enzymes involved in the generation of these lipids are dysregulated in many cancers and their inhibition reduces lung cancer growth in mouse models. However, genetic variation of enzymes involved in eicosanoid metabolism has not been adequately examined for association with lung cancer. The goal of this study was to determine whether germline genetic variation altering eicosanoid producing enzyme function and/or expression are associated with differences in lung cancer survival. We examined the association of genetic variation with mortality within eicosanoid metabolism genes in 395 non-small-cell lung cancer (NSCLC) cases from the Southern Community Cohort Study (SCCS). A total of 108 SNPs, both common and rare, in 19 genes, were examined for association. No common or rare variants were associated with lung cancer survival across the entire study population. However, rare variants in ALOX15B (arachidonate 15-lipoxygenase, type B) and the common variant rs12529 in AKR1C3 (prostaglandin F synthase) were associated with NSCLC mortality in women and African Americans, respectively. Rare variants in ALOX15B were associated with greater mortality in women (HR = 2.10, 95% CI = 1.25–3.54, p-value = 0.005). The major allele of rs12529 in AKCR1C3 associated with improved survival in African Americans (HR = 0.74, 95% CI = 0.59–0.92, p-value = 0.008). The lack of genetic associations among all NSCLC cases and the association among women only for rare variants in ALOX15B may, in part, explain the better NSCLC survival observed among women. These results raise the possibility that some subgroups within the NSCLC population may benefit from drugs targeting eicosanoid metabolism.

Novel concepts on the role of prostaglandins on luteal maintenance and maternal recognition and establishment of pregnancy in ruminants

In ruminants, the corpus luteum (CL) of early pregnancy is resistant to luteolysis. Prostaglandin (PG)E2 is considered a luteoprotective mediator. Early studies indicate that during maternal recognition of pregnancy (MRP) in ruminants, a factor(s) from the conceptus or gravid uterus reaches the ovary locally through the utero-ovarian plexus (UOP) and protects the CL from luteolysis. The local nature of the embryonic antiluteolytic or luteoprotective effect precludes any direct effect of a protein transported or acting between the gravid uterus and CL in ruminants. During MRP, interferon tau (IFNT) secreted by the trophoblast of the conceptus inhibits endometrial pulsatile release of PGF2α and increases endometrial PGE2. Our recent studies indicate that (1) luteal PG biosynthesis is selectively directed toward PGF2α at the time of luteolysis and toward PGE2 at the time of establishment of pregnancy (ESP); (2) the ability of the CL of early pregnancy to resist luteolysis is likely due to increased intraluteal biosynthesis and signaling of PGE2; and (3) endometrial PGE2 is transported from the uterus to the CL through the UOP vascular route during ESP in sheep. Intrauterine co-administration of IFNT and prostaglandin E2 synthase 1 (PGES-1) inhibitor reestablishes endometrial PGF2α pulses and regresses the CL. In contrast, intrauterine co-administration of IFNT and PGES-1 inhibitor along with intraovarian administration of PGE2 rescues the CL. Together, the accumulating information provides compelling evidence that PGE2 produced by the CL in response to endometrial PGE2 induced by pregnancy may counteract the luteolytic effect of PGF2α as an additional luteoprotective mechanism during MRP or ESP in ruminants. Targeting PGE2 biosynthesis and signaling selectively in the endometrium or CL may provide luteoprotective therapy to improve reproductive efficiency in ruminants.

Latanoprost-induced Cytokine and Chemokine Release From Human Tenon's Capsule Fibroblasts: Role of MAPK and NF-κB Signaling Pathways

PURPOSE

Long-term topical antiglaucoma therapy is considered a significant risk factor for failure of trabeculectomy. We investigated the effects of antiglaucoma drugs on proinflammatory cytokine and chemokine release from cultured human Tenon's capsule fibroblasts (HTFs) as well as the signaling pathways that underlie such effects.

MATERIALS AND METHODS

Release of the proinflammatory cytokine interleukin (IL)-6 and the chemokines IL-8 and monocyte chemotactic protein (MCP)-1 was measured with enzyme-linked immunosorbent assays. The phosphorylation (activation) of mitogen-activated protein kinases (MAPKs) as well as the phosphorylation and degradation of the nuclear factor-κB (NF-κB) inhibitor IκB-α were assessed by immunoblot analysis.

RESULTS

Latanoprost stimulated the release of IL-6, IL-8, and MCP-1 from HTFs in a concentration-dependent and time-dependent manner, whereas timolol maleate and pilocarpine had no such effects. Latanoprost also activated the MAPKs extracellular signal-regulated kinase, p38, and c-Jun NH2-terminal kinase as well as induced the phosphorylation and degradation of IκB-α in these cells. The latanoprost-induced release of IL-6, IL-8, and MCP-1 was attenuated by inhibitors of MAPK (PD98059, SB203580, or JNK inhibitor II) or NF-κB (IκB kinase 2 inhibitor) signaling pathways.

CONCLUSIONS

Latanoprost induced proinflammatory cytokine and chemokine release from HTFs in a manner dependent on MAPK and NF-κB signaling. These effects of latanoprost might influence bleb scarring after filtration surgery.

Prostaglandin F2α promotes angiogenesis and embryo-maternal interactions during implantation

Implantation in humans and other mammals is a critical period during which high embryonic mortality rates occur. Prostaglandins (PGs) are key mediators regulating interactions between the reproductive tract and the conceptus (embryo with extraembryonic membranes). Although the significance of PGF2α as a regulator of corpus luteum regression is well established, the role of its high amounts in the uterine lumen in most mammals, regardless of placentation type, during the implantation period remains unresolved. We hypothesized that PGF2α acting as an embryonic signal mediator contributes to pregnancy establishment. Using a porcine model, we demonstrated that the conceptus and its signal (estradiol-17β) elevated endometrial expression of PGF2α receptor (PTGFR) in vivo and in vitro PTGFR protein was expressed mainly in luminal epithelial (LE) and glandular epithelial cells and blood vessels in the endometrium. PGF2α stimulated the MAPK1/3 pathway in endometrial LE cells that coincided with elevated gene expression and secretion of endometrial vascular endothelial growth factor A (VEGFA) protein. PGF2α-PTGFR and adenylyl cyclase signaling were involved in this process. PGF2α-induced VEGFA acting through its receptors stimulated proliferation of endometrial endothelial cells. Moreover, PGF2α elevated gene expression of biglycan, matrix metalloproteinase 9, transforming growth factor β3, and interleukin 1α in the endometrium. In summary, our study indicates that PGF2α participates in pregnancy establishment by promoting angiogenesis and expression of genes involved in tissue remodeling and conceptus-maternal interactions in porcine endometrium during early pregnancy.

Selective modulation of the prostaglandin F2α pathway markedly impacts on endometriosis progression in a xenograft mouse model

STUDY HYPOTHESIS

Selective activation or blockade of the prostaglandin (PG) F2α receptor (FP receptor) affects ectopic endometrial tissue growth and endometriosis development.

STUDY FINDING

FP receptor antagonists might represent a promising approach for the treatment of peritoneal endometriosis.

WHAT IS KNOW ALREADY

Eutopic and ectopic endometrium from women with endometriosis exhibit higher expression of key enzymes involved in the PGF2α biosynthetic pathway. It has also been shown that the PGF2α-FP receptor interaction induces angiogenesis in human endometrial adenocarcinoma.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

For this study, a mouse model of endometriosis was developed by inoculating human endometrial biopsies into the peritoneal cavity of nude mouse (n = 15). Mice were treated with AL8810 (FP receptor antagonist), Fluprostenol (FP receptor agonist) or PBS. Endometriosis-like lesions were collected and analysed for set of markers for angiogenesis, tissue remodelling, apoptosis, cell proliferation and capillary formation using qPCR and immunohistochemistry.

MAIN RESULTS AND THE ROLE OF CHANCE

We found that selective inhibition of the FP receptor with a specific antagonist, AL8810, led to a significant decline in the number (P < 0.01) and size of endometriosis-like lesions (P < 0.001), down-regulated the expression of key mediators of tissue remodelling (MMP9, P < 0.05) and angiogenesis (VEGF, P < 0.01) and up-regulated the pro-apoptotic factor (Bax, P < 0.01) as compared with controls. Immunohistochemical analyses further showed a marked decrease in cell proliferation and capillary formation in endometrial implants from AL8810-treated mice, as determined by proliferating cell nuclear antigen (PCNA) and von Willebrand factor (vWF) immunostaining, respectively. Moreover, Fluprostenol, a selective FP receptor agonist, showed the opposite effects.

LIMITATIONS, REASONS FOR CAUTION

We carried out this study in nude mice, which have low levels of endogenous estrogens which may affect the lesion growth. Caution is required when interpreting these results to women.

WIDER IMPLICATIONS OF THE FINDINGS

This study extends the role of PG signalling in endometriosis pathogenesis and points towards the possible relevance of selective FP receptor antagonism as a targeted treatment for endometriosis.

LARGE SCALE DATA

Not Applicable.

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by grant MOP-123259 to the late Dr Ali Akoum from the Canadian Institutes for Health Research. The authors have no conflict of interest.

11β-Prostaglandin F2α, a bioactive metabolite catalyzed by AKR1C3, stimulates prostaglandin F receptor and induces slug expression in breast cancer

Prostaglandins are a group of lipid compounds involved in inflammation and cancer. We focused on PGF2α and its stereoisomer 11β-PGF2α and examined the expression and functions of their cognate receptor (FP receptor) and metabolizing enzymes (AKR1B1 and AKR1C3 respectively) in breast cancer. In immunohistochemical analysis FP receptor status associated with adverse clinical outcome only in the AKR1C3 positive cases. Therefore, we studied FP receptor-mediated functions of 11β-PGF2α using FP receptor expressed MCF-7 cell line (MCF-FP). 11β-PGF2α treatment phosphorylated ERK and CREB and induced Slug expression through FP receptor in MCF-FP, and MCF-FP cells demonstrated decreased chemosensitivity compared to parental controls. Finally, the correlation between FP receptor and Slug was also confirmed immunohistochemically in breast cancer cases. Overall these results indicated that the actions of AKR1C3 can produce FP receptor ligands whose activation results in carcinoma cell survival in breast cancer.

Generation of human endometrial knockout cell lines with the CRISPR/Cas9 system confirms the prostaglandin F2α synthase activity of aldo-ketoreductase 1B1

Prostaglandins (PGs) are important regulators of female reproductive function. The primary PGs produced in the endometrium are PGE2 and PGF2α. Relatively little is known about the biosynthetic pathways leading to the formation of PGF2α. We have described the role of aldo-ketoreductase (AKR)1B1 in increased PGF2α production by human endometrial cells following stimulation with interleukin-1β (IL-1β). However, alternate PGF synthases are expressed concurrently in endometrial cells. A definite proof of the role of AKR1B1 would require gene knockout; unfortunately, this gene has no direct equivalent in the mouse. Recently, an efficient genome-editing technology using RNA-guided DNase Cas9 and the clustered regularly interspaced short palindromic repeats (CRISPR) system has been developed. We have adapted this approach to knockout AKR1B1 gene expression in human endometrial cell lines. One clone (16-2) of stromal origin generated by the CRISPR/Cas9 system exhibited a complete loss of AKR1B1 protein and mRNA expression, whereas other clones presented with partial edition. The present report focuses on the characterization of clone 16-2 exhibiting deletion of 68 and 2 nucleotides, respectively, on each of the alleles. Cells from this clone lost their ability to produce PGF2α but maintained their original stromal cell (human endometrial stromal cells-2) phenotype including the capacity to decidualize in the presence of progesterone (medroxyprogesterone acetate) and 8-bromo-cAMP. Knockout cells also maintained their ability to increase PGE2 production in response to IL-1β. In summary, we demonstrate that the new genome editing CRISPR/Cas9 system can be used in human cells to generate stable knockout cell line models. Our results suggest that genome editing of human cell lines can be used to complement mouse KO models to validate the function of genes in differentiated tissues and cells. Our results also confirm that AKR1B1 is involved in the synthesis of PGF2α.

Diverse roles of prostaglandins in blastocyst implantation

Prostaglandins (PGs), derivatives of arachidonic acid, play an indispensable role in embryo implantation. PGs have been reported to participate in the increase in vascular permeability, stromal decidualization, blastocyst growth and development, leukocyte recruitment, embryo transport, trophoblast invasion, and extracellular matrix remodeling during implantation. Deranged PGs syntheses and actions will result in implantation failure. This review summarizes up-to-date literatures on the role of PGs in blastocyst implantation which could provide a broad perspective to guide further research in this field.

Identification of multiple and distinct defects in prostaglandin biosynthetic pathways in eutopic and ectopic endometrium of women with endometriosis

OBJECTIVE

To investigate prostaglandin (PG) biosynthesis and catabolism pathways in eutopic and ectopic endometrium of women with endometriosis.

DESIGN

Retrospective study.

SETTING

Human reproduction research laboratory.

PATIENT(S)

Forty-five women with endometriosis and 29 normal controls.

INTERVENTION(S)

Endometrial and endometriotic tissue samples were obtained during laparoscopic surgery.

MAIN OUTCOME MEASURE(S)

Cyclo-oxygenases (Coxs 1 and 2), PGE2 synthases (microsomal [m] PGES 1 and 2 and cytosolic [c] PGES), PGF2α synthases (aldoketoreductase [AKR]-1C3 and AKR-1B1), and the PG catabolic enzyme 15-hydroxyprostaglandin dehydrogenase messenger RNA expression by quantitative real-time polymerase chain reaction and protein localization by immunohistochemistry.

RESULT(S)

This study showed a marked increase in the key PG biosynthesis enzymes Cox-2, mPGES-1, mPGES-2, cPGES, and AKR-1C3 in ectopic endometrial tissue of women with endometriosis, particularly in the earliest and most active stages of the disease, without a noticeable change in the expression of the PG catabolic enzyme 15-hydroxyprostaglandin dehydrogenase. Meanwhile, the significant increase in rate-limiting Cox-2 expression upstream was correlated downstream by a significant stage- and cycle phase-dependent decrease in the terminal specific synthase mPGES-2, thereby revealing the presence of counter-regulatory mechanisms, which operate in the eutopic endometrium of women with endometrium but seem to be lacking in the ectopic implantation sites.

CONCLUSION(S)

This study reveals for the first time multiple defects in PG biosynthesis pathways, which differ between eutopic intrauterine and ectopic endometrial tissues and may, owing to the wide spectrum of PG properties, contribute to the initial steps of endometrial tissue growth and development and have an important role to play in the pathogenesis and symptoms of this disease.

Emerging roles of immune cells in luteal angiogenesis

In the mammalian ovary, the corpus luteum (CL) is a unique transient endocrine organ displaying rapid angiogenesis and time-dependent accumulation of immune cells. The CL closely resembles 'transitory tumours', and the rate of luteal growth equals that of the fastest growing tumours. Recently, attention has focused on multiple roles of immune cells in luteal function, not only in luteolysis (CL disruption by immune responses involving T lymphocytes and macrophages), but also in CL development (CL remodelling by different immune responses involving neutrophils and macrophages). Neutrophils and macrophages regulate angiogenesis, lymphangiogenesis, and steroidogenesis by releasing cytokines in the CL. In addition, functional polarisation of neutrophils (proinflammatory N1 vs anti-inflammatory N2) and macrophages (proinflammatory M1 vs anti-inflammatory M2) has been demonstrated. This new concept concurs with the phenomenon of immune function within the luteal microenvironment: active development of the CL infiltrating anti-inflammatory N2 and M2 versus luteal regression together with proinflammatory N1 and M1. Conversely, excessive angiogenic factors and leucocyte infiltration result in indefinite disordered tumour development. However, the negative feedback regulator vasohibin-1 in the CL prevents excessive tumour-like vasculogenesis, suggesting that CL development has well coordinated time-dependent mechanisms. In this review, we discuss the physiological roles of immune cells involved in innate immunity (e.g. neutrophils and macrophages) in the local regulation of CL development with a primary focus on the cow.

Non-steroid anti-inflammatory drugs, prostaglandins, and cancer

Fatty acids are involved in multiple pathways and play a pivotal role in health. Eicosanoids, derived from arachidonic acid, have received extensive attention in the field of cancer research. Following release from the phospholipid membrane, arachidonic acid can be metabolized into different classes of eicosanoids through cyclooxygenases, lipoxygenases, or p450 epoxygenase pathways. Non-steroid anti-inflammatory drugs (NSAIDs) are widely consumed as analgesics to relieve minor aches and pains, as antipyretics to reduce fever, and as anti-inflammatory medications. Most NSAIDs are nonselective inhibitors of cyclooxygenases, the rate limiting enzymes in the formation of prostaglandins. Long term use of some NSAIDs has been linked with reduced incidence and mortality in many cancers. In this review, we appraise the biological activities of prostanoids and their cognate receptors in the context of cancer biology. The existing literature supports that these lipid mediators are involved to a great extent in the occurrence and progression of cancer.

Effect of conceptus on expression of prostaglandin F2α receptor in the porcine endometrium

Increased synthesis of prostaglandin F(2α) (PGF(2α)) in the endometrium and conceptus during the implantation period results in elevated concentration of PGF(2α) in the uterine lumen in pregnant gilts. PGF(2α) exerts its effects through PGF(2α) receptor (PTGFR), a G-protein-coupled receptor. However, besides studies concerning the function of PTGFR in endometrial abnormalities, the role of PTGFR in the endometrium during early pregnancy has not been elucidated. Therefore, the aim of this study was: (1) to evaluate the profile of PTGFR gene and protein expression in the porcine endometrium during early pregnancy and the estrous cycle; (2) to determine if the effect of conceptus on PTGFR expression is dependent on type of endometrial cells-luminal epithelial (LE) or stromal (ST) cells; and (3) to elucidate if the putative effect of conceptus on endometrial PTGFR expression is mediated by estrogen receptor. We evaluated the expression pattern of PTGFR gene and protein in the endometrium during day 9, 11, 12, 15, and 18 of the estrous cycle and pregnancy (N = 4-6 per group). The expression of PTGFR mRNA was greater on day 18 of pregnancy and the estrous cycle (vs. days 9-15 of the estrous cycle and pregnancy, P < 0.05). Expression of PTGFR protein was approximately 10-fold upregulated in the endometrium on day 15 of pregnancy when compared with day 15 of the estrous cycle (P < 0.01). Endometrial expression of PTGFR protein increased from day 12 to 18 of pregnancy (P < 0.05). PTGFR mRNA was expressed in LE and ST cells. In a subsequent experiment, we used a coculture model in which LE cells were cultured on collagen-coated inserts placed in wells plated with ST cells. Day 11 or 15 conceptus-exposed medium (CEM) elevated expression of PTGFR mRNA (2- and 1.5-fold, respectively, P < 0.05) in LE cells cocultured with ST cells. CEM did not have an effect on PTGFR mRNA expression in ST cells. The 11-day CEM-induced increase of PTGFR mRNA was abolished by incubation of LE cells in the presence of the estrogen receptor antagonist (ICI-182,780; P < 0.01). Summarizing, the conceptus upregulated expression of PTGFR in the endometrium during the implantation period. Moreover, this study indicates that expression of PTGFR gene was elevated in LE cells of endometrium by embryonic signal of estradiol. Our results suggest para- and autocrine effects of PGF(2α) through its receptor PTGFR in the porcine endometrium, especially in luminal epithelium which is in direct contact with the conceptus during the implantation period.

Steroid regulation of menstrual bleeding and endometrial repair

The ovarian steroid hormones progesterone and estradiol are well established regulators of human endometrial function. However, more recent evidence suggests that androgens and locally generated steroids, such as the glucocorticoids, also have a significant impact on endometrial breakdown and repair. The temporal and spatial pattern of steroid receptor presence in endometrial cells has a significant impact on the endometrial response to steroids. Furthermore, regulation of steroid receptor function by modulatory proteins further refines local responses. This review focuses on steroid regulation of endometrial function during the luteo-follicular transition with a focus on menstruation and endometrial repair.

Decreased levels of AKR1B1 and AKR1B10 in cancerous endometrium compared to adjacent non-cancerous tissue

Endometrial cancer is associated with enhanced cell proliferation due to high concentrations of estrogens, and decreased cell differentiation due to low levels of progesterone and retinoic acid. It is also associated with aberrant inflammatory responses and concomitant increased production of prostaglandins. The human members of the aldo-keto reductase 1B (AKR1B) subfamily, AKR1B1 and AKR1B10, have roles in these processes and can thus be implicated in endometrial cancer. To date, there have been no reports on the expression of AKR1B1 in endometrial cancer, while AKR1B10 has only been studied at the cellular level. To evaluate the roles of these AKR1B enzymes, we investigated expression of AKR1B1 and AKR1B10 in 47 paired samples of cancerous and adjacent control endometrium at the mRNA and protein levels, by quantitative PCR, Western blotting and immunohistochemistry staining. There were significantly lower mRNA and protein levels of AKR1B1 in cancerous tissues compared to adjacent endometrium. The gene expression of AKR1B10 at the mRNA level was significantly increased, while there were significantly decreased protein levels. Immunohistochemistry revealed that both of these enzymes were present in all of the samples, and are located in epithelial cells of cancerous and control endometrial glands. Elevated levels in adjacent non-cancerous tissues imply that these enzymes are more important in the initiation of endometrial cancer than in its progression. To the best of our knowledge, this is the first report on the expression of AKR1B1 and AKR1B10 in endometrial cancer. Further studies are needed to define the precise roles of these enzymes in the pathogenesis of endometrial cancer.

Expression of prostaglandin F2α (PGF2α) receptor and its isoforms in the bovine corpus luteum during the estrous cycle and PGF2α-induced luteolysis

Prostaglandin F2α (PGF2α) induces luteolysis via a specific receptor, PTGFR. Although PTGFR mRNA expression in the bovine corpus luteum (CL) has been studied previously, changes in PTGFR protein and its localization are not fully understood during the life span of the CL. In addition to full-length PTGFR, several types of PTGFR isoforms, such as PTGFRα (type I) and PTGFRζ (type II), were reported in the bovine CL, suggesting isoform-specific luteal action. Full-length PTGFR mRNA in the bovine CL increased from the early to the mid-luteal phase and decreased during luteolysis, whereas PTGFR protein remained stable. PTGFR protein was localized to both luteal and endothelial cells and was expressed similarly during the life span of the CL. Like full-length PTGFR mRNA, PTGFRα and PTGFRζ mRNA also increased from the early to mid-luteal phases, and mRNA of PTGFRζ, but not PTGFRα, decreased in the regressing CL. During PGF2α-induced luteolysis, the mRNAs of full-length PTGFR, PTGFR,α and PTGFRζ decreased rapidly (from 5 or 15 min after PGF2α injection), but PTGFR protein decreased only 12 h later. Silencing full-length PTGFR using small interfering RNA prevented PGF2α-stimulated cyclooxygenase-2 (PTGS2) mRNA induction. By contrast, PGF2α could stimulate vascular endothelial growth factor A (VEGFA) mRNA even when full-length PTGFR was knocked down, thus suggesting that PGF2α may stimulate PTGS2 via full-length PTGFR, whereas VEGFA is stimulated via other PTGFR isoforms. Collectively, PTGFR protein was expressed continually in the bovine CL during the estrous cycle, implying that PGF2α could function throughout this period. Additionally, the bovine CL expresses different PTGFR isoforms, and thus PGF2α may have different effects when acting via full-length PTGFR or via PTGFR isoforms.

Molecular characterization of prostaglandin F receptor (FP) and E receptor subtype 1 (EP₁) in zebrafish

Prostaglandins E (PGE) and F (PGF) mediate diverse physiological functions via their cell surface receptors - prostaglandin E receptor (EP) subtypes 1, 2, 3 and 4 (EP(1); EP(2); EP(3); EP(4)) and F receptor (FP). In teleost fishes, PGE was implicated in gill epithelium ion transport, while both PGE and PGF were involved in oocyte maturation, follicular rupture and coordination of reproductive behaviors. However, little is known about the mechanisms behind their actions. In present study, we first identified the full-length ORF cDNA clones of three zebrafish prostaglandin E receptor subtype 1 (zEP(1)) isoforms - zEP(1a), zEP(1b) and zEP(1c) - and FP (zFP) from adult ovary. RT-PCR showed that zEP(1a), zEP(1b) and zFP are widely expressed in adult tissues, while zEP(1c) mRNA expression is mainly confined in brain and kidney. Using a pGL3-NFAT-RE luciferase reporter system, both zEP(1a) and zEP(1b) expressed in DF-1 cells were shown to be activated by PGE(2) potently while zEP(1c) and zFP were activated by PGF(2a) effectively, suggesting that the four receptors are functionally coupled to intracellular Ca(2+)-signaling pathway. Furthermore, EP1a and EP1b, but not EP1c were suggested to couple to cAMP-PKA signaling pathway using a pGL3-CRE luciferase reporter assay. Although zEP(1c) might originate as a paralog to zEP(1a) and zEP(1b), its functional coupling to PGF(2α) instead of PGE(2) suggested that zEP(1) isoforms might have sub-functionalized in their ligand binding and G protein coupling specificity, in addition to differential tissue distribution. Characterization of these receptors undoubtedly furthered our understanding on the diverse yet highly target-specific responses of prostaglandins in teleosts.

Emerging avenues linking inflammation and cancer

The role of inflammation in carcinogenesis has been extensively investigated and well documented. Many biochemical processes that are altered during chronic inflammation have been implicated in tumorigenesis. These include shifting cellular redox balance toward oxidative stress; induction of genomic instability; increased DNA damage; stimulation of cell proliferation, metastasis, and angiogenesis; deregulation of cellular epigenetic control of gene expression; and inappropriate epithelial-to-mesenchymal transition. A wide array of proinflammatory cytokines, prostaglandins, nitric oxide, and matricellular proteins are closely involved in premalignant and malignant conversion of cells in a background of chronic inflammation. Inappropriate transcription of genes encoding inflammatory mediators, survival factors, and angiogenic and metastatic proteins is the key molecular event in linking inflammation and cancer. Aberrant cell signaling pathways comprising various kinases and their downstream transcription factors have been identified as the major contributors in abnormal gene expression associated with inflammation-driven carcinogenesis. The posttranscriptional regulation of gene expression by microRNAs also provides the molecular basis for linking inflammation to cancer. This review highlights the multifaceted role of inflammation in carcinogenesis in the context of altered cellular redox signaling.

Cyclooxygenases and lipoxygenases in cancer

Cancer initiation and progression are multistep events that require cell proliferation, migration, extravasation to the blood or lymphatic vessels, arrest to the metastatic site, and ultimately secondary growth. Tumor cell functions at both primary or secondary sites are controlled by many different factors, including growth factors and their receptors, chemokines, nuclear receptors, cell-cell interactions, cell-matrix interactions, as well as oxygenated metabolites of arachidonic acid. The observation that cyclooxygenases and lipoxygenases and their arachidonic acid-derived eicosanoid products (prostanoids and HETEs) are expressed and produced by tumor cells, together with the finding that these enzymes can regulate cell growth, survival, migration, and invasion, has prompted investigators to analyze the roles of these enzymes in cancer progression. In this review, we focus on the contribution of cyclooxygenase- and lipoxygenase-derived eicosanoids to tumor cell function in vitro and in vivo and discuss hope and tribulations of targeting these enzymes for cancer prevention and treatment.

Prostanoids in tumor angiogenesis: therapeutic intervention beyond COX-2

Prostanoids regulate angiogenesis in carcinoma and chronic inflammatory disease progression. Although prostanoid biosynthetic enzymes and signaling have been extensively analyzed in inflammation, little is known about how prostanoids mediate tumor-induced angiogenesis. Targeted cyclooxygenase (COX)-2 inhibition in tumor, stromal and endothelial cells is an attractive antiangiogenic strategy; however, the associated cardiovascular side effects have led to the development of a new generation of nonsteroidal anti-inflammatory drugs (NSAIDs) acting downstream of COX. These agents target terminal prostanoid synthases and prostanoid receptors, which may also include several peroxisome proliferator-activated receptors (PPARs). Here, we discuss the role of prostanoids as modulators of tumor angiogenesis and how prostanoid metabolism reflects complex cell-cell crosstalk that determines tumor growth. Finally, we discuss the potential of new NSAIDs for the treatment of angiogenesis-dependent tumor development.

Enzymes of the AKR1B and AKR1C Subfamilies and Uterine Diseases

Endometrial and cervical cancers, uterine myoma, and endometriosis are very common uterine diseases. Worldwide, more than 800,000 women are affected annually by gynecological cancers, as a result of which, more than 360,000 die. During their reproductive age, about 70% of women develop uterine myomas and 10-15% suffer from endometriosis. Uterine diseases are associated with aberrant inflammatory responses and concomitant increased production of prostaglandins (PG). They are also related to decreased differentiation, due to low levels of protective progesterone and retinoic acid, and to enhanced proliferation, due to high local concentrations of estrogens. The pathogenesis of these diseases can thus be attributed to disturbed PG, estrogen, and retinoid metabolism and actions. Five human members of the aldo-keto reductase 1B (AKR1B) and 1C (AKR1C) superfamilies, i.e., AKR1B1, AKR1B10, AKR1C1, AKR1C2, and AKR1C3, have roles in these processes and can thus be implicated in uterine diseases. AKR1B1 and AKR1C3 catalyze the formation of PGF2α, which stimulates cell proliferation. AKR1C3 converts PGD2 to 9α,11β-PGF2, and thus counteracts the formation of 15-deoxy-PGJ2, which can activate pro-apoptotic peroxisome-proliferator-activated receptor γ. AKR1B10 catalyzes the reduction of retinal to retinol, and thus lessens the formation of retinoic acid, with potential pro-differentiating actions. The AKR1C1-AKR1C3 enzymes also act as 17-keto- and 20-ketosteroid reductases to varying extents, and are implicated in increased estradiol and decreased progesterone levels. This review comprises an introduction to uterine diseases and AKR1B and AKR1C enzymes, followed by an overview of the current literature on the AKR1B and AKR1C expression in the uterus and in uterine diseases. The potential implications of the AKR1B and AKR1C enzymes in the pathophysiologies are then discussed, followed by conclusions and future perspectives.

The regulation of vascular endothelial growth factor by hypoxia and prostaglandin F₂α during human endometrial repair

CONTEXT

The human endometrium has an exceptional capacity for repeated repair after menses, but its regulation remains undefined. Premenstrually, progesterone levels fall and prostaglandin (PG) F₂α synthesis increases, causing spiral arteriole constriction. We hypothesized that progesterone withdrawal, PGF₂α, and hypoxia increase vascular endothelial growth factor (VEGF), an endometrial repair factor.

DESIGN AND RESULTS

Endometrial biopsies were collected (n = 47) with ethical approval and consent. VEGF mRNA, quantified by quantitative RT-PCR, was increased during menstruation (P < 0.01).VEGF protein was maximally secreted from proliferative endometrial explants. Treatment of an endometrial epithelial cell line and primary human endometrial stromal cells with 100 nm PGF₂α or hypoxia (0.5% O₂) resulted in significant increases in VEGF mRNA and protein. VEGF was maximal when cells were cotreated with PGF(2α) and hypoxia simultaneously (P < 0.05-0.001). Secretory-phase endometrial explants also showed an increase in VEGF with cotreatment (P < 0.05). However, proliferative-phase explants showed no increase in VEGF on treatment with PGF₂α and/or hypoxia. Proliferative tissue was induced to increase VEGF mRNA expression when exposed to progesterone and its withdrawal in vitro but only in the presence of hypoxia and PG. Hypoxia-inducible factor-1α (HIF-1α) silencing with RNA interference suppressed hypoxia-induced VEGF expression in endometrial cells but did not alter PGF₂α-induced VEGF expression.

CONCLUSIONS

Endometrial VEGF is increased at the time of endometrial repair. Progesterone withdrawal, PGF₂α, and hypoxia are necessary for this perimenstrual VEGF expression. Hypoxia acts via HIF-1α to increase VEGF, whereas PGF₂α acts in a HIF-1α-independent manner. Hence, two pathways regulate the expression of VEGF during endometrial repair.

International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress

It is now more than 15 years since the molecular structures of the major prostanoid receptors were elucidated. Since then, substantial progress has been achieved with respect to distribution and function, signal transduction mechanisms, and the design of agonists and antagonists (http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=58). This review systematically details these advances. More recent developments in prostanoid receptor research are included. The DP(2) receptor, also termed CRTH2, has little structural resemblance to DP(1) and other receptors described in the original prostanoid receptor classification. DP(2) receptors are more closely related to chemoattractant receptors. Prostanoid receptors have also been found to heterodimerize with other prostanoid receptor subtypes and nonprostanoids. This may extend signal transduction pathways and create new ligand recognition sites: prostacyclin/thromboxane A(2) heterodimeric receptors for 8-epi-prostaglandin E(2), wild-type/alternative (alt4) heterodimers for the prostaglandin FP receptor for bimatoprost and the prostamides. It is anticipated that the 15 years of research progress described herein will lead to novel therapeutic entities.

The expression and regulation of adrenomedullin in the human endometrium: a candidate for endometrial repair

After menstruation, the endometrium has a remarkable capacity for repair, but the factors involved remain undefined. We hypothesize adrenomedullin (AM) plays a role in this process. Premenstrually progesterone levels decline, stimulating prostaglandin (PG) synthesis, vasoconstriction, and hypoxia. This study aimed to determine 1) AM expression throughout the menstrual (M) cycle and 2) its regulation by PG and hypoxia. Human endometrial biopsies (n = 51) were collected with ethical approval and consent. AM mRNA expression was examined by quantitative RT-PCR and was found to be selectively elevated in endometrium from the menstrual (M) phase (P < 0.001). AM immunohistochemical staining was maximal in M and proliferative (P) endometrium. Culture of secretory, but not P, explants with 100 nm PGF(2α) or hypoxia (0.5% O2) increased AM mRNA (P < 0.05). P explants were induced to increase AM expression using in vitro progesterone withdrawal but required the presence of hypoxia (P < 0.05). Short hairpin sequences against hypoxia-inducible factor-1α (HIF-1α) inhibited AM hypoxic up-regulation but did not alter PGF(2α)-induced expression. The AM receptor was immunolocalized to endothelial cells in both lymphatic and blood vessels. Conditioned medium from PGF(2α)-treated cells increased endothelial cell proliferation and branching (P < 0.05). This was abolished by AM receptor antagonists. In conclusion, AM is elevated at the time of endometrial repair and induces both angiogenesis and lymphangiogenesis by stimulating endothelial cell proliferation and tube formation. In the human endometrium, AM expression is up-regulated by two mechanisms: a HIF-1α-mediated hypoxic induction and a HIF-1α-independent PGF(2α) pathway. These physiological mechanisms may provide novel therapeutic targets for disorders such as heavy menstrual bleeding.

Novel insights into the mechanisms of pregnancy establishment: regulation of prostaglandin synthesis and signaling in the pig

Ovarian progesterone induces essential changes leading to a temporary state of uterine receptivity for conceptus implantation. Estrogens secreted by the porcine conceptus on days 11 and 12 of pregnancy provide the initial signal for maternal recognition of pregnancy and maintenance of a functional corpus luteum (CL) for continued production of progesterone. As prostaglandins F(2)(α) (PGF(2)(α)) and E(2) (PGE(2)) exert opposing actions on the CL, a tight control over their synthesis and secretion is critical either for the initiation of luteolysis or maintenance of pregnancy. One of the supportive mechanisms by which conceptus inhibits luteolysis is changing PG synthesis in favor of luteoprotective PGE(2). Conceptus PGE(2) could be amplified by PGE(2) feedback loop in the endometrium. In pigs, as in other species, implantation and establishment of pregnancy is associated with upregulation of expression of proinflammatory factors, which include cytokines, growth factors, and lipid mediators. The conceptus produces inflammatory mediators: interferon γ and interferon δ, interleukins IL1B and IL6, and PGs, which probably activate inflammatory pathways in the endometrium. The endometrium responds to these embryonic signals by enhancing further progesterone-induced uterine receptivity. Understanding the mechanisms of pregnancy establishment is required for translational research to increase reproductive efficiencies and fertility in humans and animals.

Progesterone: a pivotal hormone at menstruation

The human endometrium is exposed to repeated inflammation every month, culminating in tissue breakdown and menstruation. Subsequently, the endometrium has a remarkable capacity for efficient repair and remodeling to enable implantation if fertilization takes place. Endometrial function is known to be governed by the ovarian hormones estradiol and progesterone. This review paper focuses on hormonal control of the cyclical tissue injury and repair that takes place in the local endometrial environment at the time of menstruation. Progesterone levels decline premenstrually as the corpus luteum regresses in the absence of pregnancy, and estradiol levels increase during the postmenstrual phase. The functional impact of these significant changes is discussed, including their immediate and downstream effects. Finally, we examine the contribution of aberrant endometrial function to the presentation of heavy menstrual bleeding and identify potential therapeutic targets for the treatment of this common gynecological problem.

PGF2α-F-prostanoid receptor signalling via ADAMTS1 modulates epithelial cell invasion and endothelial cell function in endometrial cancer

Background

An increase in cancer cell invasion and microvascular density is associated with a poorer prognosis for patients with endometrial cancer. In endometrial adenocarcinoma F-prostanoid (FP) receptor expression is elevated, along with its ligand prostaglandin (PG)F_2α, where it regulates expression and secretion of a host of growth factors and chemokines involved in tumorigenesis. This study investigates the expression, regulation and role of a disintegrin and metalloproteinase with thrombospondin repeat 1 (ADAMTS1) in endometrial adenocarcinoma cells by PGF_2α via the FP receptor.

Methods

Human endometrium and adenocarcinoma tissues were obtained in accordance with Lothian Research Ethics Committee guidance with informed patient consent. Expression of ADAMTS1 mRNA and protein in tissues was determined by quantitative RT-PCR analysis and immunohistochemistry. Signal transduction pathways regulating ADAMTS1 expression in Ishikawa cells stably expressing the FP receptor to levels seen in endometrial cancer (FPS cells) were determined by quantitative RT-PCR analysis. In vitro invasion and proliferation assays were performed with FPS cells and human umbilical vein endothelial cells (HUVECs) using conditioned medium (CM) from PGF_2α-treated FPS cells from which ADAMTS1 was immunoneutralised and/or recombinant ADAMTS1. The role of endothelial ADAMTS1 in endothelial cell proliferation was confirmed with RNA interference. The data in this study were analysed by T-test or ANOVA.

Results

ADAMTS1 mRNA and protein expression is elevated in endometrial adenocarcinoma tissues compared with normal proliferative phase endometrium and is localised to the glandular and vascular cells. Using FPS cells, we show that PGF2α-FP signalling upregulates ADAMTS1 expression via a calmodulin-NFAT-dependent pathway and this promotes epithelial cell invasion through ECM and inhibits endothelial cell proliferation. Furthermore, we show that CM from FPS cells regulates endothelial cell ADAMTS1 expression in a rapid biphasic manner. Using RNA interference we show that endothelial cell ADAMTS1 also negatively regulates cellular proliferation.

Conclusions

These data demonstrate elevated ADAMTS1 expression in endometrial adenocarcinoma. Furthermore we have highlighted a mechanism whereby FP receptor signalling regulates epithelial cell invasion and endothelial cell function via the PGF_2α-FP receptor mediated induction of ADAMTS1.

Chorionic gonadotrophin regulates CXCR4 expression in human endometrium via E-series prostanoid receptor 2 signalling to PI3K-ERK1/2: implications for fetal-maternal crosstalk for embryo implantation

Murine knock-out models and blastocyst co-culture studies have identified prostaglandin-endoperoxide synthase (PTGS) 2, prostaglandin (PG) E receptor 2 (PTGER2) and the chemokine receptor CXCR4 as important regulators of early pregnancy events. In vitro studies and studies in non-human primates have shown that these proteins are regulated in the endometrium by the early embryonic signal, chorionic gonadotrophin (CG). Here we show that expressions of PTGER2 and CXCR4 are elevated during the mid-secretory phase of the menstrual cycle and decidua of early pregnancy in humans. Using first trimester decidua explants, we show that CG induces expression of PTGS2 and biosynthesis of PGE₂, and expression of PTGER2. Subsequently, PGE₂via PTGER2 induces expression of CXCR4. Using an in vitro model system of Ishikawa endometrial epithelial cells stably expressing PTGER2 and human first trimester decidua explants, we demonstrate that CXCR4 expression is regulated by PTGER2 via the epidermal growth factor receptor (EGFR)-phosphatidylinositol-3-kinase (PI3K)-extracellular signal-regulated kinase (ERK1/2) pathway.Taken together, our data suggest that early embryonic signals may regulate fetal–maternal crosstalk in the human endometrium by inducing CXCR4 expression via the PGE₂–PTGER2-mediated induction of the EGFR, PI3K and ERK1/2 pathways.

Suppressed expression of type 2 3alpha/type 5 17beta-hydroxysteroid dehydrogenase (AKR1C3) in endometrial hyperplasia and carcinoma

The diagnosis of endometrial hyperplasia and endometrial type adenocarcinoma arising within the uterine cavity has long been rested on morphologic criteria. Although distinction between normal endometrial epithelium from adenocarcinoma is usually straightforward, the separation between normal and hyperplastic endometrium, particularly those cases without atypia, can be a diagnostic challenge. The same is true in separation of hyperplastic endometrium with atypia from endometrial-type endometrial adenocarcinoma. Type 2 3alpha-/type 5 17beta-hydroxysteroid dehydrogenase (HSD) (AKR1C3) is a multifunctional enzyme involved in androgen, estrogen, progesterone, and pros-taglandin metabolism. Its expression has been shown in the epithelium of the renal tubules, urothelial epithelium, and endothelial cells in normal tissues as well as in prostatic adenocarcinoma. The proliferation and maintenance of endometrial epithelium is dependent on both estrogen and progesterone; and AKR1C3-mediated steroid metabolism may play a critical role in the maintenance of viable normal and abnormal endometrial epithelium. We studied the expression of AKR1C3 in 33 endometrial biopsy specimens including 13 cases of normal proliferative endometrium, 8 cases of hyperplastic endometrium with and without atypia, and 12 cases of primary endometrial adenocarcinoma of endometrial type. We demonstrated a uniform, diffuse, and strong expression of AKR1C3 in normal endometrial epithelium but not in endometrial stromal cells. In contrast, the expression of AKR1C3 is reduced in both hyperplastic and carcinomatous endometrial epithelium. These findings suggest that AKR1C3 may play important roles in the physiology of endometrial cells and that suppressed AKR1C3 expression may represent a feature that allows differentiation of hyperplastic and neoplastic endometrial epithelium from normal endometrial epithelium. However, reduced AKR1C3 expression cannot distinguish hyperplastic endometrium from endometrial adenocarcinoma of endometrial type. The biologic and pathological roles of AKR1C3 in endometrial epithelium require further investigation.

Prostaglandin F2alpha differentially affects mRNA expression relating to angiogenesis, vasoactivation and prostaglandins in the early and mid corpus luteum in the cow

Administration of prostaglandin (PG) F(2alpha) in cattle during the mid-luteal phase (Days 8-12 of the estrous cycle) drastically reduces the plasma progesterone concentrations and the volume of the corpus luteum (CL). However, PGF(2alpha) does not induce luteolysis during the early luteal phase (up to Day 5 of the estrous cycle). To characterize the possible distinct difference in acute response to a luteolytic dose of PGF(2alpha) administration, we determined various mRNA expressions in the early and mid CL relating to angiogenesis, vasoactivation and PG-related factors at 30 min after PGF(2alpha) injection in cyclic cows. The experiments were conducted on Day 4 (early CL) and Days 10-12 (mid CL). Cows were either injected with 500 microg PGF(2alpha) analogue or saline as the control (early CL control, n=5; early CL PGF(2alpha) treated, n=5; mid CL control, n=5; mid CL PGF(2alpha) treated, n=7). Thirty min after injection of PGF(2alpha) or saline, the cows were ovariectomized transvaginally, and the CL tissues were collected from regions designated as the periphery and center of the CL. Administration of PGF(2alpha) up-regulated the mRNA expressions of angiogenic-related factors such as vascular endothelial growth factors, vasohibin, fibroblast growth factor 2 and insulin-like growth factor-II in the early CL, whereas PGF(2alpha) down-regulated these mRNA expressions in the mid CL. In the vasoactive factors, PGF(2alpha) stimulated the mRNA expressions of endothelin-1, angiotensin converting enzyme, endothelial nitric oxide synthase (NOS) and inducible NOS in the periphery area of the mid CL, but not in the early CL. However, PGF(2alpha) drastically down-regulated PGF(2alpha) receptor mRNA expression in both regions of the early and mid CL. The results indicated a clear difference in the acute action of PGF(2alpha) depending not only on the luteal phase (immature vs. mature) but also the region (periphery vs. center) within the CL at 30 min after PGF(2alpha) injection in the cow.

Eicosanoids and cancer

Eicosanoids, including prostaglandins and leukotrienes, are biologically active lipids that have been implicated in various pathological processes, such as inflammation and cancer. This Review highlights our understanding of the intricate roles of eicosanoids in epithelial-derived tumours and their microenvironment. The knowledge of how these lipids orchestrate the complex interactions between transformed epithelial cells and the surrounding stromal cells is crucial for understanding tumour evolution, progression and metastasis. Understanding the molecular mechanisms underlying the role of prostaglandins and other eicosanoids in cancer progression will help to develop more effective cancer chemopreventive and/or therapeutic agents.