Downregulation of 15-PGDH enhances MASH-HCC development via fatty acid-induced T-cell exhaustion.

Background & Aims: Hepatocellular carcinoma (HCC) mainly develops from chronic hepatitis. Metabolic dysfunction-associated steatohepatitis (MASH) has gradually become the main pathogenic factor for HCC given the rising incidence of obesity and metabolic diseases. 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) degrades prostaglandin 2 (PGE2), which is known to exacerbate inflammatory responses. However, the role of PGE2 accumulation caused by 15-PGDH downregulation in the development of MASH-HCC has not been determined. Methods: We utilised the steric animal model to establish a MASH-HCC model using wild-type and 15-Pgdh+/- mice to assess the significance of PGE2 accumulation in the development of MASH-HCC. Additionally, we analysed clinical samples obtained from patients with MASH-HCC. Results: PGE2 accumulation in the tumour microenvironment induced the production of reactive oxygen species in macrophages and the expression of cell growth-related genes and antiapoptotic genes. Conversely, the downregulation of fatty acid metabolism in the background liver promoted lipid accumulation in the tumour microenvironment, causing a decrease in mitochondrial membrane potential and CD8+ T-cell exhaustion, which led to enhanced development of MASH-HCC. Conclusions: 15-PGDH downregulation inactivates immune surveillance by promoting the proliferation of exhausted effector T cells, which enhances hepatocyte survival and proliferation and leads to the development of MASH-HCC. Impact and implications: The suppression of PGE2-related inflammation and subsequent lipid accumulation leads to a reduction in the severity of MASH and inhibition of subsequent progression toward MASH-HCC.

Inhibition of Prostaglandin-Degrading Enzyme 15-PGDH Mitigates Acute Murine Lung Allograft Rejection.

PURPOSE: Acute rejection is a frequent complication among lung transplant recipients and poses substantial therapeutic challenges. 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme responsible for the inactivation of prostaglandin E2 (PGE2), has recently been implicated in inflammatory lung diseases. However, the role of 15-PGDH in lung transplantation rejection remains elusive. The present study was undertaken to examine the expression of 15-PGDH in rejected lung allografts and whether inhibition of 15-PGDH ameliorates acute lung allograft rejection. METHODS: Orthotopic mouse lung transplantations were performed between donor and recipient mice of the same strain or allogeneic mismatched pairs. The expression of 15-PGDH in mouse lung grafts was measured. The efficacy of a selective 15-PGDH inhibitor (SW033291) in ameliorating acute rejection was assessed through histopathological examination, micro-CT imaging, and pulmonary function tests. Additionally, the mechanism underlying the effects of SW033291 treatment was explored using CD8+ T cells isolated from mouse lung allografts. RESULTS: Increased 15-PGDH expression was observed in rejected allografts and allogeneic CD8+ T cells. Treatment with SW033291 led to an accumulation of PGE2, modulation of CD8+ T-cell responses and mitochondrial activity, and improved allograft function and survival. CONCLUSION: Our study provides new insights into the role of 15-PGDH in acute lung rejection and highlights the therapeutic potential of inhibiting 15-PGDH for enhancing graft survival. The accumulation of PGE2 and modulation of CD8+ T-cell responses represent potential mechanisms underlying the benefits of 15-PGDH inhibition in this model. Our findings provide impetus for further exploring 15-PGDH as a target for improving lung transplantation outcomes.

Ginsenoside Rb1 Promotes Hepatic Glycogen Synthesis to Ameliorate T2DM Through 15-PGDH/PGE2/EP4 Signaling Pathway.

Purpose: Ginsenoside Rb1 (Rb1), one of the crucial bioactive constituents in Panax ginseng C. A. Mey., possesses anti-type 2 diabetes mellitus (T2DM) property. Nevertheless, the precise mechanism, particularly the impact of Rb1 on hepatic glycogen production, a crucial process in the advancement of T2DM, remains poorly understood. 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is responsible for prostaglandin E2 (PGE2) inactivation. A recent study has reported that inhibition of 15-PGDH promoted hepatic glycogen synthesis and improved T2DM. Therefore, herein, we aimed to investigate whether Rb1 ameliorated T2DM through 15-PGDH/PGE2-regulated hepatic glycogen synthesis. Methods: By combining streptozotocin with a high-fat diet, we successfully established a mouse model for T2DM. Afterward, these mice were administered Rb1 or metformin for 8 weeks. An insulin-resistant cell model was established by incubating LO2 cells with palmitic acid. Liver glycogen and PGE2 levels, the expression levels of 15-PGDH, serine/threonine kinase AKT (AKT), and glycogen synthase kinase 3 beta (GSK3ß) were measured. Molecular docking was used to predict the binding affinity between 15-PGDH and Rb1. Results: Rb1 administration increased the phosphorylation levels of AKT and GSK3ß to enhance glycogen synthesis in the liver of T2DM mice. Molecular docking indicated that Rb1 had a high affinity for 15-PGDH. Moreover, Rb1 treatment resulted in the suppression of elevated 15-PGDH levels and the elevation of decreased PGE2 levels in the liver of T2DM mice. Furthermore, in vitro experiments showed that Rb1 administration might enhance glycogen production by modulating the 15-PGDH/PGE2/PGE2 receptor EP4 pathway. Conclusion: Our findings indicate that Rb1 may enhance liver glycogen production through a 15-PGDH-dependent pathway to ameliorate T2DM, thereby offering a new explanation for the positive impact of Rb1 on T2DM and supporting its potential as an effective therapeutic approach for T2DM.

[Altered expression of 15-hydroxyprostaglandin dehydrogenase in chronic rhinosinusitis with nasal polyps].

Objective:To investigate the expression level and regulatory mechanism of 15-hydroxyprostaglandin dehydrogenase（HPGD） in chronic rhinosinusitis with nasal polyps（CRSwNP）. Methods:The expression pattern and level of HPGD in CRSwNP and control was observed using immunofluorescence, and western blot was used for analysis of HPGD expression in nasal polyp tissues. The effect of recombinant human high mobility group box-1（HMGB1） on HPGD expression in primary human nasal epithelial cells was observed, and the potential blocking effect of RAGE neutralizing antibody on HMGB1-induced HPGD expression was investigated. Results:The expression of HPGD was elevated in CRSwNP patients compared to the control, while the protein mainly localized at CD68-positive cells and epithelial cells. Recombinant human HMGB1 stimulated an increase in HPGD expression in primary human nasal mucosal epithelial cells at a time-dependent manner. Additionally, increased phosphorylation levels of MEK and elevated RAGE expression were also observed at 12 hours, but decreased at 24 hours after the incubation of HMGB1. The increase in the expression of HPGD induced by HMGB1 in primary human nasal epithelial cells was partly inhibited with RAGE neutralizing antibody. Conclusion:Elevated HPGD expression is observed in CRSwNP, predominantly in macrophages and epithelial cells. HMGB1 regulates HPGD expression through the RAGE-MEK signaling pathway, potentially providing a new target for future regulation of PGE2levels in CRSwNP.

15-Hydroxyprostaglandin dehydrogenase inhibitor SW033291 ameliorates hepatic abnormal lipid metabolism, ER stress, and inflammation through PGE2/EP4 in T2DM mice.

Type 2 diabetes mellitus (T2DM) is a rapidly growing epidemic that results in increased morbidity, mortality, and soaring medical costs. Prostaglandin E2 (PGE2), a vital lipid mediator, has been reported to protect against hepatic steatosis, inflammation, endoplasmic reticulum (ER) stress, and insulin resistance, indicating its potential therapeutic role in T2DM. PGE2 can be degraded by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). SW033291, an inhibitor of 15-PGDH, has been reported to increase PGE2 levels, however, the effect of SW033291 in T2DM remains to be explored. This study aims to evaluate whether SW033291 protects against T2DM and explore its potential mechanisms. A T2DM mouse model was established through high-fat diet/streptozotocin injection, while palmitic acid-treated mouse primary hepatocytes were used as insulin-resistant cell models. SW033291 treatment reduced body weight, fat weight, fasting blood glucose, and improved impaired glucose tolerance and insulin resistance in T2DM mice. More importantly, SW033291 alleviated steatosis, inflammation, and ER stress in the liver of T2DM mice. Mechanistically, SW033291 decreased the expressions of SREBP-1c and ACC1, and increased the expression of PPARα in T2DM mice. Additionally, SW033291 inhibited NF-κB and eIF2α/CHOP signaling in T2DM mice. Further, we showed that the protective effects of SW033291 on the above-mentioned pathophysiological processes could be hindered by inhibition of the PGE2 receptor EP4. Overall, our study reveals a novel role of SW033291 in alleviating T2DM and suggests its potential as a new therapeutic strategy for T2DM.

Identification and characterization of bioactive metabolites of 12-hydroxyheptadecatrienoic acid, a ligand for leukotriene B4 receptor 2.

12(S)-hydroxyheptadecatrienoic acid (12-HHT) is a bioactive fatty acid synthesized from arachidonic acid via the cyclooxygenase pathway and serves as an endogenous ligand for the low-affinity leukotriene B4 receptor 2 (BLT2). Although the 12-HHT/BLT2 axis contributes to the maintenance of epithelial homeostasis, 12-HHT metabolism under physiological conditions is unclear. In this study, 12-keto-heptadecatrienoic acid (12-KHT) and 10,11-dihydro-12-KHT (10,11dh-12-KHT) were detected as 12-HHT metabolites in the human megakaryocytic cell line MEG01s. We found that 12-KHT and 10,11dh-12-KHT are produced from 12-HHT by 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and prostaglandin reductase 1 (PTGR1), key enzymes in the degradation of prostaglandins, respectively. The 15-PGDH inhibitor SW033291 completely suppressed the production of 12-KHT and 10,11dh-12-KHT in MEG01s cells, resulting in a 9-fold accumulation of 12-HHT. 12-KHT and 10,11dh-12-KHT were produced in mouse skin wounds, and the levels were significantly suppressed by SW033291. Surprisingly, the agonistic activities of 12-KHT and 10,11dh-12-KHT on BLT2 were comparable to that of 12-HHT. Taken together, 12-HHT is metabolized into 12-KHT by 15-PGDH, and then 10,11dh-12-KHT by PTGR1 without losing the agonistic activity.

Altered expression of 15-hydroxyprostaglandin dehydrogenase in chronic rhinosinusitis with nasal polyps / 临床耳鼻咽喉头颈外科杂志

Objective:To investigate the expression level and regulatory mechanism of 15-hydroxyprostaglandin dehydrogenase（HPGD） in chronic rhinosinusitis with nasal polyps（CRSwNP）. Methods:The expression pattern and level of HPGD in CRSwNP and control was observed using immunofluorescence, and western blot was used for analysis of HPGD expression in nasal polyp tissues. The effect of recombinant human high mobility group box-1（HMGB1） on HPGD expression in primary human nasal epithelial cells was observed, and the potential blocking effect of RAGE neutralizing antibody on HMGB1-induced HPGD expression was investigated. Results:The expression of HPGD was elevated in CRSwNP patients compared to the control, while the protein mainly localized at CD68-positive cells and epithelial cells. Recombinant human HMGB1 stimulated an increase in HPGD expression in primary human nasal mucosal epithelial cells at a time-dependent manner. Additionally, increased phosphorylation levels of MEK and elevated RAGE expression were also observed at 12 hours, but decreased at 24 hours after the incubation of HMGB1. The increase in the expression of HPGD induced by HMGB1 in primary human nasal epithelial cells was partly inhibited with RAGE neutralizing antibody. Conclusion:Elevated HPGD expression is observed in CRSwNP, predominantly in macrophages and epithelial cells. HMGB1 regulates HPGD expression through the RAGE-MEK signaling pathway, potentially providing a new target for future regulation of PGE2levels in CRSwNP.

Sp1-Induced SETDB1 Overexpression Transcriptionally Inhibits HPGD in a ß-Catenin-Dependent Manner and Promotes the Proliferation and Metastasis of Gastric Cancer.

PURPOSE: Gastric cancer (GC) has high morbidity and mortality, the cure rate of surgical treatment and drug chemotherapy is not ideal. Therefore, development of new treatment strategies is necessary. We aimed to identify the mechanism underlying Sp1 regulation of GC progression. METHODS AND METHODS: The levels of Sp1, ß-catenin, SET domain bifurcated 1 (SETDB1), and 15-hydroxyprostaglandin dehydrogenase (HPGD) were detected by quantitative reverse transcription polymerase chain reaction and western blot analysis. The targets of SETDB1 were predicted by AnimalTFDB, and dual-luciferase reporter assay was used for confirming the combination of Sp1, ß-catenin, and SETDB1. HGC27 or AGS cells (1×106 cells/mouse) were injected into mice via the caudal vein for GC model establishment. The level of Ki67 was detected using immunohistochemistry, and hematoxylin and eosin staining was performed for evaluating tumor metastasis in mice with GC. RESULTS: HPGD was inhibited, while the protein levels of Sp1, ß-catenin, and SETDB1 were up-regulated in GC tissues and cell lines. HPGD overexpression or SETDB1 silencing inhibited the proliferation, invasion, and migration of GC cells, and Sp1 regulated the proliferation, invasion, and migration of GC cells in a ß-catenin-dependent manner. Furthermore, HPGD served as a target of SETDB1, and it was negatively regulated by SETDB1; additionally, Sp1 and ß-catenin bound to the SETDB1 promoter and negatively regulated HPGD expression. We proved that Sp1 regulated GC progression via the SETDB1/HPGD axis. CONCLUSIONS: Our findings revealed that Sp1 transcriptionally inhibited HPGD via SETDB1 in a ß-catenin-dependent manner and promoted the proliferation and metastasis of GC cells.

MiR-106b-5p regulates esophageal squamous cell carcinoma progression by binding to HPGD.

BACKGROUND: Several studies have documented the key role of microRNAs (miRNAs) in esophageal squamous cell carcinoma (ESCC). Although the expression of the 15-hydroxyprostaglandin dehydrogenase (HPGD) gene and miR-106b-5p are reportedly linked to cancer progression, their underlying mechanisms in ESCC remain unclear. METHODS: mRNA and miRNA expression in ESCC tissues and cells were analyzed using RT-qPCR. Luciferase and RNA pull-down assays were used to identify the interaction between miR-106b-5p and HPGD. Xenograft and pulmonary metastasis models were used to assess tumor growth and metastasis. CCK-8, BrdU, colony formation, adhesion, cell wound healing, Transwell, and caspase-3/7 activity assays, and flow cytometry and western blot analyses were used to examine the function of miR-106-5p and HPGD in ESCC cell lines. RESULTS: The findings revealed that miR-106b-5p expression was upregulated in ESCC tissues and cell lines. miR-106b-5p augmented cellular proliferation, colony formation, adhesion, migration, invasion, and proportion of cells in the S-phase, but reduced apoptosis and the proportion of cells in G1-phase. Silencing of miR-106-5p inhibited tumor growth in vivo and pulmonary metastasis. Although HPGD overexpression suppressed proliferation, colony formation, adhesion, migration, and invasion of ESCC cells, it promoted apoptosis and caused cell cycle arrest of the ESCC cells. The results also indicated a direct interaction of HPGD with miR-106b-5p in ESCC cells. Furthermore, miR-106b-5p inhibited HPGD expression, thereby suppressing ESCC tumorigenesis. CONCLUSION: Our data suggest that miR-106b-5p enhances proliferation, colony formation, adhesion, migration, and invasion, and induces the cycle progression, but represses apoptosis of ESCC cells by targeting HPGD. This suggests that the miR-106b-5p/HPGD axis may serve as a promising target for the diagnosis and treatment of ESCC.

Upregulation of prostaglandin E2 by inducible microsomal prostaglandin E synthase-1 in colon cancer.

PURPOSE: Prostaglandin E2 (PGE2) is known to promote carcinogenesis and cancer progression in colon cancer. Enzymes involved in the metabolism of PGE2 include cyclooxygenase (COX)-2, microsomal prostaglandin E synthase-1 (mPGES-1), and 15-prostaglandin dehydrogenase (15-PGDH). The current study aims to determine how PGE2 is expressed by examining patients with colorectal cancer and evaluating colon cancer cells to gain insight into changes in relevant enzymes upon induction of PGE2. METHODS: The concentration of PGE2 was measured in tumor tissues and adjacent normal mucosal tissues of 26 patients with colon cancer. The expression of COX-1, COX-2, mPGES-1, and 15-PGDH proteins was measured. The concentration of PGE2 in FET colon cancer cells was measured both in the initial status and after stimulation by tumor necrosis factor (TNF)-α. The expression levels of PGE2-related enzymes were measured as well. RESULTS: There was no significant difference in the average concentration of PGE2, which was measured at 453.1 pg/mL in cancer tissues and 401.2 pg/mL in normal mucosa. Among PGE2-related enzymes, 15-PGDH was expressed at a lower level in tumor cells than in normal mucosa. In colon cancer cells, PGE2 was found to be upregulated upon stimulation by TNF-α, which led to strong induction of mPGES-1 without any change in the expression of COX-2 among the PGE2-related enzymes. CONCLUSION: These results demonstrated that PGE2 can be induced by stimuli such as TNF-α, and suggest that activation of mPGES-1 is more closely related than that of COX-2 in the induction of PGE2 on colon cancer.

Monocyte dysfunction in decompensated cirrhosis is mediated by the prostaglandin E2-EP4 pathway.

BACKGROUND & AIMS: Infection is a major problem in advanced liver disease secondary to monocyte dysfunction. Elevated prostaglandin (PG)E2 is a mediator of monocyte dysfunction in cirrhosis; thus, we examined PGE2 signalling in outpatients with ascites and in patients hospitalised with acute decompensation to identify potential therapeutic targets aimed at improving monocyte dysfunction. METHODS: Using samples from 11 outpatients with ascites and 28 patients hospitalised with decompensated cirrhosis, we assayed plasma levels of PGE2 and lipopolysaccharide (LPS); performed quantitative real-time PCR on monocytes; and examined peripheral blood monocyte function. We performed western blotting and immunohistochemistry for PG biosynthetic machinery expression in liver tissue. Finally, we investigated the effect of PGE2 antagonists in whole blood using polychromatic flow cytometry and cytokine production. RESULTS: We show that hepatic production of PGE2 via the cyclo-oxygenase 1-microsomal PGE synthase 1 pathway, and circulating monocytes contributes to increased plasma PGE2 in decompensated cirrhosis. Transjugular intrahepatic sampling did not reveal whether hepatic or monocytic production was larger. Blood monocyte numbers increased, whereas individual monocyte function decreased as patients progressed from outpatients with ascites to patients hospitalised with acute decompensation, as assessed by Human Leukocyte Antigen (HLA)-DR isotype expression and tumour necrosis factor alpha and IL6 production. PGE2 mediated this dysfunction via its EP4 receptor. CONCLUSIONS: PGE2 mediates monocyte dysfunction in decompensated cirrhosis via its EP4 receptor and dysfunction was worse in hospitalised patients compared with outpatients with ascites. Our study identifies a potential drug target and therapeutic opportunity in these outpatients with ascites to reverse this process to prevent infection and hospital admission. LAY SUMMARY: Patients with decompensated cirrhosis (jaundice, fluid build-up, confusion, and vomiting blood) have high infection rates that lead to high mortality rates. A white blood cell subset, monocytes, function poorly in these patients, which is a key factor underlying their sensitivity to infection. We show that monocyte dysfunction in decompensated cirrhosis is mediated by a lipid hormone in the blood, prostaglandin E2, which is present at elevated levels, via its EP4 pathway. This dysfunction worsens when patients are hospitalised with complications of cirrhosis compared with those in the outpatients setting, which supports the EP4 pathway as a potential therapeutic target for patients to prevent infection and hospitalisation.

Downregulation of 15-hydroxyprostaglandin dehydrogenase during acquired tamoxifen resistance and association with poor prognosis in ERα-positive breast cancer.

AIM: Tamoxifen (TAM) resistance remains a clinical issue in breast cancer. The authors previously reported that 15-hydroxyprostaglandin dehydrogenase (HPGD) was significantly downregulated in tamoxifen-resistant (TAMr) breast cancer cell lines. Here, the authors investigated the relationship between HPGD expression, TAM resistance and prediction of outcome in breast cancer. METHODS: HPGD overexpression and silencing studies were performed in isogenic TAMr and parental human breast cancer cell lines to establish the impact of HPGD expression on TAM resistance. HPGD expression and clinical outcome relationships were explored using immunohistochemistry and in silico analysis. RESULTS: Restoration of HPGD expression and activity sensitised TAMr MCF-7 cells to TAM and 17ß-oestradiol, whilst HPGD silencing in parental MCF-7 cells reduced TAM sensitivity. TAMr cells released more prostaglandin E2 (PGE2) than controls, which was reduced in TAMr cells stably transfected with HPGD. Exogenous PGE2 signalled through the EP4 receptor to reduce breast cancer cell sensitivity to TAM. Decreased HPGD expression was associated with decreased overall survival in ERα-positive breast cancer patients. CONCLUSIONS: HPGD downregulation in breast cancer is associated with reduced response to TAM therapy via PGE2-EP4 signalling and decreases patient survival. The data offer a potential target to develop combination therapies that may overcome acquired tamoxifen resistance.

Relationship between expression level of 15-PGDH and clinical prognosis of liver transplantation for hepatocellular carcinoma / 器官移植

Objective To investigate the relationship between the expression level of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and clinical prognosis of liver transplantation for hepatocellular carcinoma. Methods The clinical data of 94 recipients undergoing liver transplantation for hepatocellular carcinoma were retrospectively analyzed. The expression of 15-PGDH in the pathological tissues of all recipients was detected by immunohistochemical staining. The relationship between the expression level of 15-PGDH protein and clinical parameters of hepatocellular carcinoma patients was analyzed. The 5-year tumor-free survival and overall survival rates of liver transplant recipients were calculated. The possible independent risk factors of the clinical prognosis of liver transplant recipients were analyzed. Results The expression level of 15-PGDH was significantly correlated with age, Child-Pugh grade and preoperative level of alpha-fetoprotein (AFP) of the recipients (all P < 0.05). The tumor-free survival and overall survival rates of the recipients with low expression of 15-PGDH were significantly lower than those in their counterparts with high expression of 15-PGDH (both P < 0.05). The expression level of 15-PGDH, degree of tumor differentiation and American Joint Committee on Cancer (AJCC) staging were the independent risk factors of clinical prognosis of liver transplantation for hepatocellular carcinoma (all P < 0.05). Conclusions The expression level of 15-PGDH is an independent risk factor of clinical prognosis of liver transplantation for hepatocellular carcinoma.

15-Keto prostaglandin E2 suppresses STAT3 signaling and inhibits breast cancer cell growth and progression.

Overproduction of prostaglandin E2 (PGE2) has been linked to enhanced tumor cell proliferation, invasiveness and metastasis as well as resistance to apoptosis. 15-Keto prostaglandin E2 (15-keto PGE2), a product formed from 15-hydroxyprostaglandin dehydrogenase-catalyzed oxidation of PGE2, has recently been shown to have anti-inflammatory and anticarcinogenic activities. In this study, we observed that 15-keto PGE2 suppressed the phosphorylation, dimerization and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) in human mammary epithelial cells transfected with H-ras (MCF10A-ras). 15-Keto PGE2 inhibited the migration and clonogenicity of MCF10A-ras cells. In addition, subcutaneous injection of 15-keto PGE2 attenuated xenograft tumor growth and phosphorylation of STAT3 induced by breast cancer MDA-MB-231 cells. However, a non-electrophilic analogue, 13,14-dihydro-15-keto PGE2 failed to inhibit STAT3 signaling and was unable to suppress the growth and transformation of MCF10A-ras cells. These findings suggest that the α,ß-unsaturated carbonyl moiety of 15-keto PGE2 is essential for its suppression of STAT3 signaling. We observed that the thiol reducing agent, dithiothreitol abrogated 15-keto PGE2-induced STAT3 inactivation and disrupted the direct interaction between 15-keto PGE2 and STAT3. Furthermore, a molecular docking analysis suggested that Cys251 and Cys259 residues of STAT3 could be preferential binding sites for this lipid mediator. Mass spectral analysis revealed the covalent modification of recombinant STAT3 by 15-keto PGE2 at Cys259. Taken together, thiol modification of STAT3 by 15-keto PGE2 inactivates STAT3 which may account for its suppression of breast cancer cell proliferation and progression.

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 /PGF2α 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.

The prostanoid pathway contains potential prognostic markers for glioblastoma.

Prostanoids derived from the activity of cyclooxygenases and their respective synthases contribute to both active inflammation and immune response in the tumor microenvironment. Their synthesis, deactivation and role in glioma biology have not yet been fully explored and require further study. Using quantitative real time PCR, gas chromatography/ electron impact mass spectrometry and liquid chromatography/ electrospray ionization tandem mass spectrometry, we have further characterized the prostanoid pathway in grade IV glioblastoma (GBM). We observed significant correlations between high mRNA expression levels and poor patient survival for microsomal PGE synthase 1 (mPGES1) and prostaglandin reductase 1 (PTGR1). Conversely, high mRNA expression levels for 15-hydroxyprostaglandin dehydrogenase (15-HPGD) were correlated with better patient survival. GBMs had a higher quantity of the prostanoid precursor, arachidonic acid, versus grade II/III tumors and in GBMs a significant positive correlation was found between arachidonic acid and PGE2 content. GBMs also had higher concentrations of TXB2, PGD2, PGE2 and PGF2α versus grade II/III tumors. A significant decrease in survival was detected for high versus low PGE2, PGE2 + PGE2 deactivation products (PGEMs) and PGF2α in GBM patients. Our data show the potential importance of prostanoid metabolism in the progression towards GBM and provide evidence that higher PGE2 and PGF2α concentrations in the tumor are correlated with poorer patient survival. Our findings highlight the potential importance of the enzymes 15-HPGD and PTGR1 as prognostic biomarkers which could be used to predict survival outcome of patients with GBM.

Electrophilic derivatives of omega-3 fatty acids counteract lung cancer cell growth.

PURPOSE: 17-oxo-DHA is an electrophilic keto-derivative of the omega-3 fatty acid docosahexaenoic acid (DHA) endogenously generated by cyclooxygenase-2 and a cellular dehydrogenase. 17-oxo-DHA displays anti-inflammatory and cytoprotective actions. DHA, alone or in combination with standard chemotherapy, displays antitumor activity. However, the effects of electrophilic keto-derivatives of DHA on cancer growth have never been evaluated. We investigated whether 17-oxo-DHA, alone or in combination with gemcitabine, displayed antitumor effects. Furthermore, we evaluated whether the enzyme 15-prostaglandin dehydrogenase (15-PGDH) was required for transducing the antitumor effects of DHA. METHODS: A panel of five histologically different human non-small cell lung cancer (NSCLC) cell lines was used. Cells were treated with 17-oxo-DHA and gemcitabine, alone or in combination, and apoptosis, proliferation, Fas and FasL expression (mRNA and protein) and active caspase-3/7 and -8 were assessed. Furthermore, an inhibitor of 15-PGDH was used to test the involvement of this enzyme in mediating the antitumor effects of DHA. RESULTS: 17-oxo-DHA (50 µM, 72 h) significantly reduced proliferation, increased cell apoptosis, Fas and FasL expression as well as active caspase-8 and -3/7. When 17-oxo-DHA was given in combination with gemcitabine, stronger effects were observed compared to gemcitabine alone. The enzyme 15-PGDH was required for DHA to promote its full anti-apoptotic effect suggesting that enzymatically generated keto-derivatives of DHA mediate its antitumor actions. CONCLUSIONS: Data herein provided, demonstrate that 17-oxo-DHA displays antitumor effects in NSCLC cell lines. Of note, the combination of 17-oxo-DHA plus gemcitabine, resulted in stronger anticancer effects compared to gemcitabine alone.

ROS-Mediated 15-Hydroxyprostaglandin Dehydrogenase Degradation via Cysteine Oxidation Promotes NAD+-Mediated Epithelial-Mesenchymal Transition.

Nicotinamide adenine dinucleotide (NAD) levels decrease with aging as a result of aging-associated CD38 upregulation. Here, we established a cell model with decreased cellular NAD levels by overexpressing CD38 or treating cells with FK866, an inhibitor of nicotinamide phosphoribosyltransferase. We revealed that decreased NAD triggered reactive oxygen species (ROS)-mediated degradation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH), which drove cells to undergo epithelial-mesenchymal transition (EMT). Moreover, we showed that oxidation of the Cys44 residue to sulfonic acid in 15-PGDH led to its degradation via non-canonical ubiquitination-proteasome and autophagy pathways. Mutation of Cys44 to alanine abolished ROS-induced 15-PGDH degradation. We demonstrated that 15-PGDH silencing promoted EMT, whereas supplementation with NAD precursors increased NAD and 15-PGDH stability, and reversed the EMT process. Taken together, these results suggest that declining NAD levels contribute to age-dependent increases in cancer incidence, and repletion of NAD precursors is beneficial for increasing 15-PGDH expression.