Novel anti-cancer effect of 2-arachidonoylglycerol via processing body formation in HCA-7 human colon cancer cells.

The endocannabinoid 2-arachidonoylglycerol (2-AG) has been reported to exhibit anticancer effects, including against colorectal cancer (CRC); however, the detailed mechanisms have not been clarified. Herein, we demonstrated that 2-AG suppressed cyclooxygenase-2 (COX-2) expression induced by prostaglandin E2 in human colon cancer HCA-7 cells. The suppression of COX-2 expression by 2-AG was through the acceleration of processing body (P-body) formation followed by COX-2 mRNA degradation. These effects were restored by TAK-715, a specific inhibitor of p38 MAPK. Therefore, the effect of 2-AG on COX-2 may be distinct from conventional non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs inhibit the function of COX-2, whereas 2-AG suppresses the protein expression of COX-2. Recently, the cardiovascular risks of NSAIDs were reported by the Food and Drug Administration in the United States. Therefore, elucidation of the effect of 2-AG is expected to contribute to the development of an alternative and novel therapeutic option that would have no or fewer risks regarding cardiovascular events.

Phosphatidylcholine-Plasmalogen-Oleic Acid Reduces BACE1 Expression in Human SH-SY5Y Cells.

Plasmalogens are a family of glycerophospholipids containing one vinyl-ether bond at the sn-1 position in the glycerol backbone, and play important roles in cellular homeostasis including neural transmission. Therefore, reductions of plasmalogens have been associated with neurodegenerative disorders, such as Alzheimer's disease (AD). To evaluate the potential protective effects of plasmalogens against the pathology of AD, protein expression levels of key factors in amyloid precursor protein (APP) metabolic processes were examined using human neuroblastoma SH-SY5Y cells. Here, phosphatidylcholine-plasmalogen-oleic acid (PC-PLS-18) was shown to reduce protein expression levels of ß-site APP cleaving enzyme 1 (BACE1), clusterin, and Tau, factors involved in the amyloid ß-associated pathogenesis of AD. Thus, PC-PLS-18 may have preventive effects against AD by delaying the onset risk for a certain period.

Individual resolvin E family members work distinctly and in a coordinated manner in the resolution of inflammation.

Three main E-type resolvins (RvEs): RvE1, RvE2, and RvE3, have roles in the resolution of inflammation as anti-inflammatory activities. To investigate the roles of each RvE in the resolution of inflammation, timing of interleukin (IL)- 10 release and IL-10 receptor expressions, and phagocytosis evoked by each RvE in differentiated human monocytes, macrophage-like U937 cells were examined. Here, we show that RvEs enhance the expression of IL-10, and IL-10 receptor-mediated signaling pathways and IL-10-mediated-signaling-independent resolution of inflammatory effects by activating the phagocytotic function. Thus, RvE2 mainly evoked an IL-10-mediated anti-inflammatory function, whereas RvE3 principally activated phagocytotic activity of macrophages, which may be involved in tissue repair. On the other hand, RvE1 showed both functions, although not prominent but rather acting as a relief mediator that takes over the RvE2 function and passes over to the RvE3 function. Therefore, each RvE may act as an important role/stage-specific mediator in a coordinated manner with other RvEs in the processes of the resolution of inflammation.

CA9 and PRELID2; hypoxia-responsive potential therapeutic targets for pancreatic ductal adenocarcinoma as per bioinformatics analyses.

A strong hypoxic environment has been observed in pancreatic ductal adenocarcinoma (PDAC) cells, which contributes to drug resistance, tumor progression, and metastasis. Therefore, we performed bioinformatics analyses to investigate potential targets for the treatment of PDAC. To identify potential genes as effective PDAC treatment targets, we selected all genes whose expression level was related to worse overall survival (OS) in The Cancer Genome Atlas (TCGA) database and selected only the genes that matched with the genes upregulated due to hypoxia in pancreatic cancer cells in the dataset obtained from the Gene Expression Omnibus (GEO) database. Although the extracted 107 hypoxia-responsive genes included the genes that were slightly enriched in angiogenic factors, TCGA data analysis revealed that the expression level of endothelial cell (EC) markers did not affect OS. Finally, we selected CA9 and PRELID2 as potential targets for PDAC treatment and elucidated that a CA9 inhibitor, U-104, suppressed pancreatic cancer cell growth more effectively than 5-fluorouracil (5-FU) and PRELID2 siRNA treatment suppressed the cell growth stronger than CA9 siRNA treatment. Thus, we elucidated that specific inhibition of PRELID2 as well as CA9, extracted via exhaustive bioinformatic analyses of clinical datasets, could be a more effective strategy for PDAC treatment.

PARP14 regulates EP4 receptor expression in human colon cancer HCA-7 cells.

E type prostanoid 4 (EP4) receptors and their signaling pathways have been implicated in the development and malignant transformation of colorectal cancer. We herein demonstrated that the mono(ADP-ribosyl)ation of histone deacetylase (HDAC)1 and HDAC2 by poly(ADP-ribose) polymerase 14 (PARP14) may be required to induce the expression of EP4 receptors. The suppression of PARP14 activity by siRNA and/or its inhibitors reduced the mRNA expression of EP4 receptors. Thus, the expression of their proteins to approximately 50-80% in human colon cancer HCA-7 cells, however, which retained the activities of EP4 receptors to some extent. Since the expression levels of EP4 receptors are important factors for the maintenance of homeostasis, the adequate inhibition of PARP14 activity will be a good target for the prevention of colon cancer and/or as an alternative therapy for this disease. Since non-steroidal anti-inflammatory drugs (NSAIDs) are associated with a risk of heart attacks and stroke, novel PARP14 inhibitors will supersede NSAIDs without causing heart attacks and stroke, while maintaining appropriate EP4 receptor-mediated intestinal homeostasis.

Identification and Characterization of Human Colorectal Cancer Cluster Predominantly Expressing EP3 Prostanoid Receptor Subtype.

Colorectal cancer (CRC) is one of the common types of cancer in humans. Prostaglandin E2 (PGE2) is a well-known mediator of colorectal cancer through stimulation of four E-type prostanoid (EP) receptor subtypes: EP1, EP2, EP3, and EP4 receptors. All subtypes of EP receptors are involved in CRC promotion or malignancy. However, the characteristics of CRC that highly expresses EP receptor subtypes have not been clarified. In the present study, we classified CRC from a cancer genomic database and identified CRC clusters which highly express EP receptor subtypes. Most of these clusters predominantly expressed one subtype of EP receptor and showed different gene expression patterns. Among them, we focused on the cluster highly expressing the EP3 receptor (CL-EP3). As the result of characterization of gene expression, CL-EP3 was characterized as: epithelial mesenchymal transition (EMT)-induced progressed cancer with activation of transforming growth factor-ß pathway, activation of hypoxia-inducible factor-1α, and suppression of runt-related transcription factor 3. Since we previously reported that EP3 receptor is involved in and induce colon cancer cell migration, EP3 receptor-expressing CRC may induce metastasis through these signaling pathways. Thus, the findings suggest the effectiveness of cancer clustering by gene expression of the EP receptor subtype to elucidate the mechanism of human CRC.

Phosphatidylcholine-Plasmalogen-Oleic Acid Has Protective Effects against Arachidonic Acid-Induced Cytotoxicity.

Plasmalogens are a group of glycerophospholipids containing a vinyl-ether bond at the sn-1 position in the glycerol backbone. Cellular membrane plasmalogens are considered to have important roles in homeostasis as endogenous antioxidants, differentiation, and intracellular signal transduction pathways including neural transmission. Therefore, reduced levels of plasmalogens have been suggested to be associated with neurodegenerative diseases such as Alzheimer's disease. Interestingly, although arachidonic acid is considered to be involved in learning and memory, it could be liberated and excessively activate neuronal activity to the excitotoxic levels seen in Alzheimer's disease patients. Here, we examined the protective effects of several kinds of plasmalogens against cellular toxicity caused by arachidonic acid in human neuroblastoma SH-SY5Y cells. As a result, only phosphatidylcholine-plasmalogen-oleic acid (PC-PLS-18) showed protective effects against arachidonic acid-induced cytotoxicity based on the results of lactate dehydrogenase release and ATP depletion assays, as well as cellular morphological changes in SH-SY5Y cells. These results indicate that PC-PLS-18 protects against arachidonic acid-induced cytotoxicity, possibly via improving the stability of the cellular membrane in SH-SY5Y cells.

15-Keto-PGE2 acts as a biased/partial agonist to terminate PGE2-evoked signaling.

Prostaglandin E2 (PGE2) is well-known as an endogenous proinflammatory prostanoid synthesized from arachidonic acid by the activation of cyclooxygenase-2. E type prostanoid (EP) receptors are cognates for PGE2 that have four main subtypes: EP1 to EP4. Of these, the EP2 and EP4 prostanoid receptors have been shown to couple to Gαs-protein and can activate adenylyl cyclase to form cAMP. Studies suggest that EP4 receptors are involved in colorectal homeostasis and cancer development, but further work is needed to identify the roles of EP2 receptors in these functions. After sufficient inflammation has been evoked by PGE2, it is metabolized to 15-keto-PGE2 Thus, 15-keto-PGE2 has long been considered an inactive metabolite of PGE2 However, it may have an additional role as a biased and/or partial agonist capable of taking over the actions of PGE2 to gradually terminate reactions. Here, using cell-based experiments and in silico simulations, we show that PGE2-activated EP4 receptor-mediated signaling may evoke the primary initiating reaction of the cells, which would take over the 15-keto-PGE2-activated EP2 receptor-mediated signaling after PGE2 is metabolized to 15-keto-PGE2 The present results shed light on new aspects of 15-keto-PGE2, which may have important roles in passing on activities to EP2 receptors from PGE2-stimulated EP4 receptors as a "switched agonist." This novel mechanism may be significant for gradually terminating PGE2-evoked inflammation and/or maintaining homeostasis of colorectal tissues/cells functions.

Diphenhydramine may be a preventive medicine against cisplatin-induced kidney toxicity.

Cisplatin is widely used as an anti-tumor drug for the treatment of solid tumors. Unfortunately, it causes kidney toxicity as a critical side effect, limiting its use, given that no preventive drug against cisplatin-induced kidney toxicity is currently available. Here, based on a repositioning analysis of the Food and Drug Administration Adverse Events Reporting System, we found that a previously developed drug, diphenhydramine, may provide a novel treatment for cisplatin-induced kidney toxicity. To confirm this, the actual efficacy of diphenhydramine was evaluated in in vitro and in vivo experiments. Diphenhydramine inhibited cisplatin-induced cell death in kidney proximal tubular cells. Mice administered cisplatin developed kidney injury with significant dysfunction (mean plasma creatinine: 0.43 vs 0.15 mg/dl) and showed augmented oxidative stress, increased apoptosis, elevated inflammatory cytokines, and MAPKs activation. However, most of these symptoms were suppressed by treatment with diphenhydramine. Furthermore, the concentration of cisplatin in the kidney was significantly attenuated in diphenhydramine-treated mice (mean platinum content: 70.0 vs 53.4 µg/g dry kidney weight). Importantly, diphenhydramine did not influence or interfere with the anti-tumor effect of cisplatin in any of the in vitro or in vivo experiments. In a selected cohort of 98 1:1 matched patients from a retrospective database of 1467 patients showed that patients with malignant cancer who had used diphenhydramine before cisplatin treatment exhibited significantly less acute kidney injury compared to ones who did not (6.1 % vs 22.4 %, respectively). Thus, diphenhydramine demonstrated efficacy as a novel preventive medicine against cisplatin-induced kidney toxicity.

Irinotecan-induced neutropenia is reduced by oral alkalization drugs: analysis using retrospective chart reviews and the spontaneous reporting database.

PURPOSE: SN-38, an active metabolite of irinotecan, is reabsorbed by the intestinal tract during excretion, causing diarrhoea and neutropenia. In addition, the association between blood levels of SN-38 and neutropenia has been reported previously, and the rapid excretion of SN-38 from the intestinal tract is considered to prevent neutropenia. Oral alkalization drugs are used as prophylactic agents for suppressing SN-38 reabsorption. The relationship between oral alkalization drugs and neutropenia, however, has not been well studied. The aim of this study was to investigate the relationship between oral alkalization drugs and neutropenia in irinotecan-treated patients. METHODS AND RESULTS: Patients with cervical or ovarian cancer were administered irinotecan and investigated by medical chart reviews to determine whether oral alkalization drugs were effective at ameliorating irinotecan-induced neutropenia. The drug combination in the oral alkalization drugs-ursodeoxycholic acid, magnesium oxide, and sodium hydrogen carbonate-significantly improved neutrophil counts and reduced dose intensity compared with those of non-users. In the large-scale Japanese Adverse Drug Event Report database, the reporting odds ratio of irinotecan-induced neutropenia was significantly lower when irinotecan had been given in combination with oral alkalization drugs. CONCLUSIONS: These data indicate that oral alkalization drugs may reduce the frequency of neutropenia caused by irinotecan administration, making it possible to increase the dose safely.

A I131V Substitution in the Fusion Glycoprotein of Human Parainfluenza Virus Type 1 Enhances Syncytium Formation and Virus Growth.

Human parainfluenza virus type 1 (hPIV1) has two spike glycoproteins, the hemagglutinin-neuraminidase (HN) glycoprotein as a receptor-binding protein and the fusion (F) glycoprotein as a membrane-fusion protein. The F glycoprotein mediates both membrane fusion between the virus and cell and membrane fusion between cells, called syncytium formation. Wild-type C35 strain (WT) of hPIV1 shows little syncytium formation of infected cells during virus growth. In the present study, we isolated a variant virus (Vr) from the WT that showed enhanced syncytium formation of infected cells by using our previously established hPIV1 plaque formation assay. Vr formed a larger focus and showed increased virus growth compared with WT. Sequence analysis of the spike glycoprotein genes showed that the Vr had a single amino acid substitution of Ile to Val at position 131 in the fusion peptide region of the F glycoprotein without any substitutions of the HN glycoprotein. The Vr F glycoprotein showed enhanced syncytium formation in F and HN glycoprotein-expressing cells. Additionally, expression of the Vr F glycoprotein increased the focus area of the WT-infected cells. The single amino acid substitution at position 131 in the F glycoprotein of hPIV1 gives hPIV1 abilities to enhance syncytium formation and increase cell-to-cell spread. The present study supports the possibility that hPIV1 acquires increased virus growth in vitro from promotion of direct cell-to-cell transmission by syncytium formation.

Nitrosonifedipine, a Photodegradation Product of Nifedipine, Suppresses Pharmacologically Induced Aortic Aneurysm Formation.

BACKGROUND/AIMS: We have reported that nitrosonifedipine (NO-NIF), a photodegradation product of nifedipine, has strong antioxidant and endothelial protective effects, and can suppress several cardiovascular diseases in animal models. The objective of the present study was to investigate the effects of NO-NIF on aortic aneurysm formation. METHODS: The mice were infused with ß-aminopropionitrile for 2 weeks and angiotensin II for 6 weeks to induce aortic aneurysm formation. The oxidative stress was measured by dihydroethidium staining and nitrotyrosine staining. The expressions of inflammation-related genes were assessed by quantitative real-time PCR and immunohistochemical staining. To clarify the mechanisms of how NO-NIF suppresses vascular cell adhesion molecule (VCAM)-1, endothelial cells were used in in vitro system. RESULTS: NO-NIF suppressed pharmacologically induced the aortic aneurysm formation and aortic expansion without blood pressure changes. NO-NIF suppressed elastin degradation and matrix metalloproteinase-2 mRNA expression. NO-NIF suppressed the reactive oxygen species-cyclophilin A positive feedback loop. Upregulated mRNA expressions of inflammation-related genes and endothelial VCAM-1 were suppressed by NO-NIF co-treatment in aortae. CONCLUSION: NO-NIF has the potential to be a new, nifedipine-derived therapeutic drug for suppressing aortic aneurysm formation by directly improving aortic structure with its strong ability to reduce oxidative stress and inflammation.

Anti-cancer Effects of MW-03, a Novel Indole Compound, by Inducing 15-Hydroxyprostaglandin Dehydrogenase and Cellular Growth Inhibition in the LS174T Human Colon Cancer Cell Line.

Increases in the expression of prostaglandin E2 (PGE2) are widely known to be involved in aberrant growth in the early stage of colon cancer development. We herein demonstrated that the novel indole compound MW-03 reduced PGE2-induced cAMP formation by catalization to an inactive metabolite by inducing 15-hydroxyprostaglandin dehydrogenase through the activation of peroxisome proliferator-activated receptor-γ. MW-03 also inhibited colon cancer cell growth by arresting the cell cycle at the S phase. Although the target of MW-03 for cell cycle inhibition has not yet been identified, these dual anti-cancer effects of MW-03 itself and/or its leading compound(s) on colon cancer cells may reduce colon cancer development and, thus, have potential as a novel treatment for the early stage of this disease.

Consecutive oral administration of Bifidobacterium longum MM-2 improves the defense system against influenza virus infection by enhancing natural killer cell activity in a murine model.

Bifidobacterium, one of the major components of intestinal microflora, shows anti-influenza virus (IFV) potential as a probiotic, partly through enhancement of innate immunity by modulation of the intestinal immune system. Bifidobacterium longum MM-2 (MM-2), a very safe bacterium in humans, was isolated from healthy humans and its protective effect against IFV infection in a murine model shown. In mice that were intranasally inoculated with IFV, oral administration of MM-2 for 17 consecutive days improved clinical symptoms, reduced mortality, suppressed inflammation in the lower respiratory tract, and decreased virus titers, cell death, and pro-inflammatory cytokines such as IL-6 and TNF-α in bronchoalveolar lavage fluid. The anti-IFV mechanism of MM-2 involves innate immunity through significant increases in NK cell activities in the lungs and spleen and a significant increase in pulmonary gene expression of NK cell activators such as IFN-γ, IL-2, IL-12 and IL-18. Even in non-infected mice, MM-2 administration also induced significant enhancement of both IFN-γ production by Peyer's patch cells (PPs) and splenetic NK cell activity. Oral administration of MM-2 for 17 days activates systemic immunoreactivity in PPs, which contributes to innate immunity, including NK cell activation, resulting in an anti-IFV effect. MM-2 as a probiotic may function as a prophylactic agent in the management of an IFV epidemic.

Rapid Fluorescent Detection Assay for Human Parainfluenza Viruses.

Human parainfluenza virus type 1 (hPIV1) does not form clear plaque by the conventional plaque formation assay because of slightly a cytopathic effects in many cell lines infected with hPIV1, thus making in virus titration, isolation and inhibitor evaluation difficult. We have succeeded in fluorescent histochemical visualization of sialidase activities of influenza A and B viruses, Newcastle disease virus and Sendai virus by using a novel fluorescent sialidase substrate, 2-(benzothiazol-2-yl)-4-bromophenyl 5-acetamido-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosidonic acid (BTP3-Neu5Ac). In this study, we applied the BTP3-Neu5Ac assay for rapid detection of hPIV1 and hPIV type 3. The BTP3-Neu5Ac assay could histochemically visualize dot-blotted hPIVs on a membrane and hPIV-infected cells as local fluorescence under UV irradiation. We succeeded in distinct fluorescent visualization of hPIV1-infected cells in only 3 d using the BTP3-Neu5Ac assay. Due to there being no fixation, hPIV1 was isolated directly from fluorescent stained focus cells by the BTP3-Neu5Ac assay. Establishment of a sensitive, easy, and rapid fluorescent focus detection assay for hPIV, hPIV1 in particular will contribute greatly to progress in hPIV studies.

Pemafibrate inhibited renal dysfunction and fibrosis in a mouse model of adenine-induced chronic kidney disease.

AIMS: Peroxisome proliferator-activated receptor-alpha (PPARα) levels are markedly lower in the kidneys of chronic kidney disease (CKD) patients. Fibrates (PPARα agonists) are therapeutic agents against hypertriglyceridemia and potentially against CKD. However, conventional fibrates are eliminated by renal excretion, limiting their use in patients with impaired renal function. Here, we aimed to evaluate the renal risks associated with conventional fibrates via clinical database analysis and investigate the renoprotective effects of pemafibrate, a novel selective PPARα modulator mainly excreted into the bile. MAIN METHODS: The risks associated with conventional fibrates (fenofibrate, bezafibrate) to the kidneys were evaluated using the Food and Drug Administration Adverse Event Reporting System. Pemafibrate (1 or 0.3 mg/kg/day) was administered daily using an oral sonde. Its renoprotective effects were examined in unilateral ureteral obstruction (UUO)-induced renal fibrosis model mice (UUO mice) and adenine-induced CKD model mice (CKD mice). KEY FINDINGS: The ratios of glomerular filtration rate decreased and blood creatinine increased were markedly higher after conventional fibrate use. Pemafibrate administration suppressed increased gene expressions of collagen-I, fibronectin, and interleukin 1 beta (IL-1ß) in the kidneys of UUO mice. In CKD mice, it suppressed increased plasma creatinine and blood urea nitrogen levels and decreased red blood cell count, hemoglobin, and hematocrit levels, along with renal fibrosis. Moreover, it inhibited the upregulation of monocyte chemoattractant protein-1, IL-1ß, tumor necrosis factor-alpha, and IL-6 in the kidneys of CKD mice. SIGNIFICANCE: These results demonstrated the renoprotective effects of pemafibrate in CKD mice, confirming its potential as a therapeutic agent for renal disorders.

Characterization of Immune Checkpoint Inhibitor-Induced Myasthenia Gravis Using the US Food and Drug Administration Adverse Event Reporting System.

Myasthenia gravis (MG) is a rare but fatal adverse event of immune checkpoint inhibitors (ICIs). We assessed whether patient characteristics differed between those with ICI-related myasthenia gravis and those with idiopathic myasthenia gravis. Reports from the US Food and Drug Administration Adverse Event Reporting System were analyzed. Multivariate analyses were conducted to evaluate the associations between age, sex, and ICI treatment and the reporting rate of myasthenia gravis. Among 5 464 099 cases between 2011 and 2019, 53 447 were treated with ICIs. Myasthenia gravis was reported more often in ICI users. Multiple logistic regression analyses showed that the reporting rate of ICI-related myasthenia gravis did not differ significantly between men and women; however, it was higher in older people than in younger people (adjusted odds ratio, 2.4 [95%CI, 1.84-3.13]). We also investigated useful signs for the early detection of myositis and myocarditis, which are fatal when overlapping with ICI-related myasthenia gravis. Patients with elevated serum creatine kinase or troponin levels were more likely to have concurrent myositis and myocarditis. Unlike idiopathic myasthenia gravis, there was no sex difference in the development of ICI-related myasthenia gravis, which may be more common in older people. Considering the physiological muscle weakness that occurs in the elderly, it may be necessary to monitor ICI-related myasthenia gravis more closely in older people.

Characterization of Human Parainfluenza Virus Receptor Using Terminal Sialic Acid Linkage-Modified Cells.

Human parainfluenza virus type 1 (hPIV1) and type 3 (hPIV3) are respiratory pathogen viruses that bind to terminal sialic acids of glycoconjugates on the cell surface hemagglutinin-neuraminidase glycoprotein. Sialic acid residues are linked to the galactose residue primarily by α2,3 or α2,6 linkages on the terminal of glycoprotein or glycolipids. One of the major determinants of pathogenicity or tissue tropism is virus binding or infection specificity for each sialyl linkage. Sialic linkage-modified human blood cells or mammalian cells that mainly have α2,3- or α2,6-linked sialic acid residues on the surface can be prepared by treatment with linkage-specific sialidases or sialyltransferases. These linkage-modified cells can be used in hemagglutination assays to estimate virus particles' binding specificity, hemadsorption assays to estimate virus glycoproteins' binding specificity, and virus infectivity assays. These methods contribute to identifying the specificity of sialic acid lineage recognition of the hPIV or other sialic acid-binding viruses.

The Gαs-protein-mediated pathway may be steadily stimulated by prostanoid EP2 receptors, but not by EP4 receptors.

EP2 and EP4 prostanoid receptors have long been considered to have similar roles, since they are known to couple with Gαs-protein and activate cAMP-mediated signaling pathways. In this study, we re-evaluated the results of cAMP assays with or without phosphodiesterase (PDE) inhibitor pretreatment. Here, we show that in the absence of PDE inhibitor pretreatment, prostaglandin E2 causes accumulation of cAMP in EP2 receptors, whereas markedly low levels of cAMP accumulated in EP4 receptors. By applying the Black/Leff operational model calculation, we found that EP2 receptors have a biased ability to intrinsically activate the Gαs-protein-mediated pathway, whereas EP4 receptors have strong biased activity for the Gαi-protein-mediated pathway. Thus, EP2 and EP4 receptors may not be similar Gαs-coupled receptors but instead substantially different receptors with distinct roles.

Down-regulation of the expression of cyclooxygenase-2 and prostaglandin E2 by interleukin-4 is mediated via a reduction in the expression of prostanoid EP4 receptors in HCA-7 human colon cancer cells.

Chronic inflammatory bowel disease (IBD), which is characterized by prolonged inflammation of the gastrointestinal tract is associated with an increased risk of colorectal cancer. Recent studies revealed that the pathology of IBD is caused by hyperactivated immune responses mediated by differentiated CD4+ naïve helper T cells, such as Th1 and Th17 cells, but not Th2 cells. The human E-type prostanoid 4 (EP4) receptor and its pathways have also been implicated in and/or associated with the early developmental stages of colorectal cancer along with increases in the levels of prostaglandin E2 (PGE2) and cyclooxygenase-2 (COX-2), the hallmarks of colorectal carcinogenesis. In the present study, using an in silico analysis and pharmacological experiments, we demonstrated that interleukin (IL)-4, a signature cytokine of Th2 cells, down-regulated the expression of COX-2 and PGE2 in the human colon cancer cell line, HCA-7. This result may be attributed to a reduction in the expression of prostanoid EP4 receptors through the induction of hypoxia inducible factor-1α via the interleukin-4 receptor-stimulated activation of signal transducer and activator of transcription 6. However, another major Th2 cytokine IL-13 had no effect on the expression of COX-2 or prostanoid EP4 receptors in HCA-7 cells. Therefore, instead of the hyperactivation of Th1/Th17 cells, the deactivation/down-regulation of Th2 cells followed by a decrease in the production of IL-4 in IBD may play a role in the cancerous transformation of cells, at least in prostanoid EP4 receptor-overactivated tumorigenesis.