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Kitagawa K, Hamaguchi A, Fukushima K, Nakano Y, Regan JW, Mashimo M, Fujino H. Down-regulation of the expression of cyclooxygenase-2 and prostaglandin E 2 by interleukin-4 is mediated via a reduction in the expression of prostanoid EP4 receptors in HCA-7 human colon cancer cells. Eur J Pharmacol 2022; 920:174863. [PMID: 35240193 DOI: 10.1016/j.ejphar.2022.174863] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 01/17/2022] [Accepted: 02/22/2022] [Indexed: 12/18/2022]
Abstract
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.
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Affiliation(s)
- Kana Kitagawa
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Ayaka Hamaguchi
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Keijo Fukushima
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Yuki Nakano
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - John W Regan
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, 85721-0207, USA
| | - Masato Mashimo
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kyoto, 610-0311, Japan
| | - Hiromichi Fujino
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan.
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2
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Fukushima K, Senoo K, Kurata N, Regan JW, Fujino H. The Gαs‐protein‐mediated pathway may be steadily stimulated by prostanoid EP2 receptors, but not by EP4 receptors. FEBS Open Bio 2022; 12:775-783. [PMID: 35124898 PMCID: PMC8972045 DOI: 10.1002/2211-5463.13378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 01/26/2022] [Accepted: 02/04/2022] [Indexed: 11/11/2022] Open
Abstract
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.
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Affiliation(s)
- Keijo Fukushima
- Department of Pharmacology for Life Sciences Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences Tokushima University Tokushima 770‐8505 Japan
| | - Kanaho Senoo
- Department of Pharmacology for Life Sciences Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences Tokushima University Tokushima 770‐8505 Japan
| | - Naoki Kurata
- Department of Pharmacology for Life Sciences Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences Tokushima University Tokushima 770‐8505 Japan
- Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical Sciences Chiba University 1‐8‐1 Inohana, Chuo‐ku Chiba 260‐8675 Japan
| | - John W. Regan
- Department of Pharmacology & Toxicology College of Pharmacy The University of Arizona Tucson AZ 85721‐0207 USA
| | - Hiromichi Fujino
- Department of Pharmacology for Life Sciences Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences Tokushima University Tokushima 770‐8505 Japan
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3
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Okura I, Hasuoka N, Senoo K, Suganami A, Fukushima K, Regan JW, Mashimo M, Murayama T, Tamura Y, Fujino H. The differential functional coupling of phosphodiesterase 4 to human DP and EP2 prostanoid receptors stimulated with PGD 2 or PGE 2. Pharmacol Rep 2021; 73:946-953. [PMID: 33786738 DOI: 10.1007/s43440-021-00247-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND Human DP and EP2 receptors are two of the most homologically related receptors coupling with Gαs-protein, which stimulate adenylyl cyclase to produce cAMP. Indeed, both receptors are considered to be generated by tandem duplication. It has been reported that other highly homologous and closely related β1- and β2-adrenergic receptors interact distinctly with and differentially regulate cAMP-specific phosphodiesterase (PDE) 4 recruitment. METHODS First, we focused on the cAMP degradation pathways of DP and EP2 receptors stimulated by prostaglandin (PG) D2 or PGE2 using HEK cells stably expressing either human DP receptors or EP2 receptors. Then, distances between ligands and amino acids of the receptors were evaluated by molecular dynamics (MD) analysis. RESULTS We found that PGD2/EP2 receptors exerted a greater effect on PDE4 activity than PGE2/EP2 receptors. Moreover, by MD analysis, either the PGD2 or EP2 receptor was moved and the distance was shortened between them. According to the results, DP receptors retain reactivity for PGE2, but EP2 receptors may be activated only by PGE2, at least in terms of cAMP formation, through the differential functional coupling of PDE4 probably with β-arrestin. CONCLUSION Since DP receptors and EP2 receptors are considered to be duplicated genes, DP receptors may still be in a rapid evolutionary stage as a duplicated copy of EP2 receptors and have not yet sufficient selectivity for their cognate ligand, PGD2.
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Affiliation(s)
- Iori Okura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8675, Japan
| | - Nanae Hasuoka
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Kanaho Senoo
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Akiko Suganami
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Chiba, 260-8670, Japan
| | - Keijo Fukushima
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, 85721-0207, USA
| | - Masato Mashimo
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kyotanabe, Kyoto, 610-0311, Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8675, Japan
| | - Yutaka Tamura
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Chiba, 260-8670, Japan.
| | - Hiromichi Fujino
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan.
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Endo S, Suganami A, Fukushima K, Senoo K, Araki Y, Regan JW, Mashimo M, Tamura Y, Fujino H. 15-Keto-PGE 2 acts as a biased/partial agonist to terminate PGE 2-evoked signaling. J Biol Chem 2020; 295:13338-13352. [PMID: 32727851 DOI: 10.1074/jbc.ra120.013988] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/26/2020] [Indexed: 12/27/2022] Open
Abstract
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.
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Affiliation(s)
- Suzu Endo
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Akiko Suganami
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Keijo Fukushima
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Kanaho Senoo
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Yumi Araki
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, USA
| | - Masato Mashimo
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kyotanabe, Kyoto, Japan
| | - Yutaka Tamura
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Chiba, Japan.
| | - Hiromichi Fujino
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan.
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Kurata N, Tokashiki N, Fukushima K, Misao T, Hasuoka N, Kitagawa K, Mashimo M, Regan JW, Murayama T, Fujino H. Short chain fatty acid butyrate uptake reduces expressions of prostanoid EP 4 receptors and their mediation of cyclooxygenase-2 induction in HCA-7 human colon cancer cells. Eur J Pharmacol 2019; 853:308-315. [PMID: 30980797 DOI: 10.1016/j.ejphar.2019.04.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/21/2022]
Abstract
Microbiota produce short chain fatty acids (SCFAs), which are known to maintain gut homeostasis, by the fermentation of dietary fiber in the human colon. Among SCFAs, butyrate has been considered as the most physiologically effective SCFA in colorectal epithelial cells for growth and differentiation. Here we show that the E-type prostanoid 4 (EP4) receptor expression level is regulated by different concentrations of butyrate, but not by other SCFAs, in human colon cancer HCA-7 cells, through sodium-coupled monocarboxylate transporter-1 (SMCT-1)-mediated uptake followed by the activation of histone acetyltransferase: cAMP response element binding protein-binding protein/p300. Of particular interest, the prostanoid EP4 receptors are known to be expressed in normal colorectal crypt epithelial cells and maintain intestinal homeostasis by preserving mucosal integrity, while they are also known to be involved in the early stage of carcinogenesis. Thus, the links between butyrate and the expression of prostanoid EP4 receptors are both important factors for maintaining homeostasis. Based on in silico analysis, almost half of colorectal cancer tissues have lost the expression of SMCT-1 mRNA when compared with healthy corresponding tissues. Therefore, with the collapse of homeostasis systems such as a decrease in the concentration of butyrate in colorectal tissues, or reduced butyrate uptake, there is a possibility of early stage colorectal cancer development; the transformation of normal cells to the cancerous phenotype may be due to the overexpression of prostanoid EP4 receptors followed by excessive cyclooxygenase-2 induction, which are caused by a reduced amount of butyrate and/or its uptake, in/around colorectal epithelial cells.
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Affiliation(s)
- Naoki Kurata
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan; Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan
| | - Natsumi Tokashiki
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Keijo Fukushima
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Takaya Misao
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Nanae Hasuoka
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Kana Kitagawa
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan
| | - Masato Mashimo
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kyoto, 610-0311, Japan
| | - John W Regan
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, 85721-0207, USA
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan
| | - Hiromichi Fujino
- Department of Pharmacology for Life Sciences, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University, Tokushima, 770-8505, Japan.
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6
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Seira N, Yamagata K, Fukushima K, Araki Y, Kurata N, Yanagisawa N, Mashimo M, Nakamura H, Regan JW, Murayama T, Fujino H. Cellular density-dependent increases in HIF-1α compete with c-Myc to down-regulate human EP4 receptor promoter activity through Sp-1-binding region. Pharmacol Res Perspect 2018; 6:e00441. [PMID: 30455960 PMCID: PMC6230926 DOI: 10.1002/prp2.441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 09/26/2018] [Accepted: 10/11/2018] [Indexed: 12/23/2022] Open
Abstract
The up-regulated expression of E-type prostanoid (EP) 4 receptors has been implicated in carcinogenesis; however, the expression of EP4 receptors has also been reported to be weaker in tumor tissues than in normal tissues. Indeed, EP4 receptors have been suggested to play a role in the maintenance of colorectal homeostasis. This study aimed to examine the underlying mechanisms/reasons for why inconsistent findings have been reported regarding EP4 receptor expression levels in homeostasis and carcinogenesis by focusing on cellular densities. Thus, the human colon cancer HCA-7 cells, which retain some functional features of normal epithelia, and luciferase reporter genes containing wild-type or mutated EP4 receptor promoters were used for elucidating the cellular density-dependent mechanisms about the regulation of EP4 receptor expression. In silico analysis was also utilized for confirming the relevance of the findings with respect to colon cancer development. We here demonstrated that the expression of EP4 receptors was up-regulated by c-Myc by binding to Sp-1 under low cellular density conditions, but was down-regulated under high cellular density conditions via the increase in the expression levels of HIF-1α protein, which may pull out c-Myc and Sp-1 from DNA-binding. The tightly regulated EP4 receptor expression mechanism may be a critical system for maintaining homeostasis in normal colorectal epithelial cells. Therefore, once the system is altered, possibly due to the transient overexpression of EP4 receptors, it may result in aberrant cellular proliferation and transformation to cancerous phenotypes. However, at the point, EP4 receptors themselves and their mediated homeostasis would be no longer required.
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Affiliation(s)
- Naofumi Seira
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
| | - Kazuyuki Yamagata
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
| | - Keijo Fukushima
- Department of Pharmacology for Life SciencesGraduate School of Pharmaceutical Sciences & Graduate School of Biomedical SciencesTokushima UniversityTokushimaJapan
| | - Yumi Araki
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
- Department of Pharmacology for Life SciencesGraduate School of Pharmaceutical Sciences & Graduate School of Biomedical SciencesTokushima UniversityTokushimaJapan
| | - Naoki Kurata
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
- Department of Pharmacology for Life SciencesGraduate School of Pharmaceutical Sciences & Graduate School of Biomedical SciencesTokushima UniversityTokushimaJapan
| | - Naoki Yanagisawa
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
| | - Masato Mashimo
- Laboratory of PharmacologyFaculty of Pharmaceutical SciencesDoshisha Women's College of Liberal ArtsKyotanabe, KyotoJapan
| | - Hiroyuki Nakamura
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
| | - John W. Regan
- Department of Pharmacology & ToxicologyCollege of PharmacyThe University of ArizonaTucsonArizona
| | - Toshihiko Murayama
- Laboratory of Chemical PharmacologyGraduate School of Pharmaceutical SciencesChiba UniversityChuo‐ku ChibaJapan
| | - Hiromichi Fujino
- Department of Pharmacology for Life SciencesGraduate School of Pharmaceutical Sciences & Graduate School of Biomedical SciencesTokushima UniversityTokushimaJapan
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7
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Seira N, Yanagisawa N, Suganami A, Honda T, Wasai M, Regan JW, Fukushima K, Yamaguchi N, Tamura Y, Arai T, Murayama T, Fujino H. 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. Biol Pharm Bull 2018; 40:1806-1812. [PMID: 28966256 DOI: 10.1248/bpb.b17-00458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
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.
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Affiliation(s)
- Naofumi Seira
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University
| | - Naoki Yanagisawa
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University
| | - Akiko Suganami
- Department of Bioinformatics, Graduate School of Medicine, Chiba University
| | - Takuya Honda
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University
| | - Makiko Wasai
- Department of Chemistry, Graduate School of Science, Chiba University
| | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona
| | - Keijo Fukushima
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University
| | - Naoto Yamaguchi
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University
| | - Yutaka Tamura
- Department of Bioinformatics, Graduate School of Medicine, Chiba University
| | - Takayoshi Arai
- Department of Chemistry, Graduate School of Science, Chiba University
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University
| | - Hiromichi Fujino
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences & Graduate School of Biomedical Sciences, Tokushima University
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8
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Araki Y, Suganami A, Endo S, Masuda Y, Fukushima K, Regan JW, Murayama T, Tamura Y, Fujino H. PGE1and E3show lower efficacies than E2to β-catenin-mediated activity as biased ligands of EP4 prostanoid receptors. FEBS Lett 2017; 591:3771-3780. [DOI: 10.1002/1873-3468.12878] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/10/2017] [Accepted: 09/19/2017] [Indexed: 12/24/2022]
Affiliation(s)
- Yumi Araki
- Department of Molecular Pharmacology; Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences; Tokushima University; Japan
- Laboratory of Chemical Pharmacology; Graduate School of Pharmaceutical Sciences; Chiba University; Japan
| | - Akiko Suganami
- Department of Bioinformatics; Graduate School of Medicine; Chiba University; Japan
| | - Suzu Endo
- Department of Molecular Pharmacology; Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences; Tokushima University; Japan
| | - Yuta Masuda
- Department of Molecular Pharmacology; Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences; Tokushima University; Japan
| | - Keijo Fukushima
- Department of Molecular Pharmacology; Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences; Tokushima University; Japan
| | - John W. Regan
- Department of Pharmacology and Toxicology; College of Pharmacy; The University of Arizona; Tucson AZ USA
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology; Graduate School of Pharmaceutical Sciences; Chiba University; Japan
| | - Yutaka Tamura
- Department of Bioinformatics; Graduate School of Medicine; Chiba University; Japan
| | - Hiromichi Fujino
- Department of Molecular Pharmacology; Graduate School of Pharmaceutical Sciences and Graduate School of Biomedical Sciences; Tokushima University; Japan
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9
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Suganami A, Fujino H, Okura I, Yanagisawa N, Sugiyama H, Regan JW, Tamura Y, Murayama T. Human DP and EP2 prostanoid receptors take on distinct forms depending on the diverse binding of different ligands. FEBS J 2016; 283:3931-3940. [PMID: 27636113 DOI: 10.1111/febs.13899] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/12/2016] [Accepted: 09/14/2016] [Indexed: 11/30/2022]
Abstract
Human D-type prostanoid (DP) and E-type prostanoid 2 (EP2) receptors are G protein-coupled receptors and are regarded as the most closely related receptors among prostanoid receptors because they are generated by tandem duplication. The DP receptor-cognate ligand, prostaglandin D2 (PGD2 ) has the ability to activate not only DP receptors but also EP2 receptors. Likewise, the EP2 receptor-cognate ligand, prostaglandin E2 (PGE2 ) has the ability to activate DP receptors in addition to EP receptors in order to stimulate cAMP formation. However, since PGD2 and/or PGE2 activate DP and EP2 receptors to similar maximal levels, that is, their similar efficacies, differences between the ligands in each receptor have not yet been determined in detail except for their different affinities. Herein we demonstrated, using an in silico simulation to predict binding patterns among DP or EP2 receptors and PGD2 , PGE2 , or prostaglandin F2α as the reference prostanoid, that DP and EP2 receptors plausibly take on distinct forms depending on the diverse binding of different ligands. Since these ligands have the potential to make these receptors form distinct conformations with discrete signaling pathways, they are consequently regarded as endogenous biased ligands. Moreover, by using functional assays, the susceptibilities of the DP receptors to the noncognate ligands were approximately 10 times lower than those of EP2 receptors. Thus, EP2 receptors seem to be able to distinguish endogenous ligands better than DP receptors, thereby both receptors are plausibly gaining role-sharing functions with respect to one another as the copies of duplicated gene.
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Affiliation(s)
- Akiko Suganami
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Japan
| | - Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan.,Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences & Institute of Biomedical Sciences, Graduate School, Tokushima University, Japan
| | - Iori Okura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan
| | - Naoki Yanagisawa
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan
| | | | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, USA
| | - Yutaka Tamura
- Department of Bioinformatics, Graduate School of Medicine, Chiba University, Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan
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10
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Otake S, Yoshida K, Seira N, Sanchez CM, Regan JW, Fujino H, Murayama T. Cellular density-dependent down-regulation of EP4 prostanoid receptors via the up-regulation of hypoxia-inducible factor-1α in HCA-7 human colon cancer cells. Pharmacol Res Perspect 2014; 3:e00083. [PMID: 25692008 PMCID: PMC4317221 DOI: 10.1002/prp2.83] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Revised: 07/28/2014] [Accepted: 08/07/2014] [Indexed: 12/27/2022] Open
Abstract
Increases in prostaglandin E2 (PGE2) and cyclooxygenase-2 (COX-2) levels are features of colon cancer. Among the different E-type prostanoid receptor subtypes, EP4 receptors are considered to play a crucial role in carcinogenesis by, for example, inducing COX-2 when stimulated with PGE2. However, EP4 receptor levels and PGE2-induced cellular responses are inconsistent among the cellular conditions. Therefore, the connections responsible for the expression of EP4 receptors were investigated in the present study by focusing on cell density-induced hypoxia-inducible factor-1α (HIF-1α). The expression of EP4 receptors was examined using immunoblot analysis, quantitative polymerase chain reaction, and reporter gene assays in HCA-7 human colon cancer cells with different cellular densities. The involvement of HIF-1α and its signaling pathways were also examined by immunoblot analysis, reporter gene assays, and with siRNA. We here demonstrated that EP4 receptors as well as EP4 receptor-mediated COX-2 expression levels decreased with an increase in cellular density. In contrast, HIF-1α levels increased in a cellular density-dependent manner. The knockdown of HIF-1α by siRNA restored the expression of EP4 receptors and EP4 receptor-mediated COX-2 in cells at a high density. Thus, the cellular density-dependent increase observed in HIF-1α expression levels reduced the expression of COX-2 by decreasing EP4 receptor levels. This novel regulation mechanism for the expression of EP4 receptors by HIF-1α may provide an explanation for the inconsistent actions of PGE2. The expression levels of EP4 receptors may vary depending on cellular density, which may lead to the differential activation of their signaling pathways by PGE2. Thus, cellular density-dependent PGE2-mediated signaling may determine the fate/stage of cancer cells, i.e., the surrounding environments could define the fate/stage of malignancies associated with colon cancer.
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Affiliation(s)
- Sho Otake
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, 260-8675, Japan
| | - Kenji Yoshida
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, 260-8675, Japan
| | - Naofumi Seira
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, 260-8675, Japan
| | - Christopher M Sanchez
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona Tucson, Arizona, 85721-0207
| | - John W Regan
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona Tucson, Arizona, 85721-0207
| | - Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, 260-8675, Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University Chuo-ku, Chiba, 260-8675, Japan
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11
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Oyama S, Fujino H, Yamazaki R, Okura I, Regan JW, Awata A, Arai T, Murayama T. A novel indole compound, AWT-489, inhibits prostaglandin D2-induced CD55 expression by acting on DP prostanoid receptors as an antagonist in LS174T human colon cancer cells. Arch Biochem Biophys 2013; 541:21-9. [PMID: 24239863 DOI: 10.1016/j.abb.2013.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/17/2013] [Accepted: 10/29/2013] [Indexed: 11/18/2022]
Abstract
Indoles are composed of a common core structure, the indole ring, and are widely used as pharmaceuticals and their precursors. In this study, a newly composed relatively small indole compound, AWT-489 was examined to find a novel specific antagonist for DP receptors; the cognate receptors for prostaglandin D2 (PGD2), to prevent colon cancer malignancy. Here we showed that AWT-489 antagonized DP receptor-mediated cyclic AMP formation, and expression of CD55, an inhibitor of the complement system that correlates with poor survival in patients with colorectal cancer, in LS174T human colon cancer cells. Interestingly, unlike a popular indole compound, indomethacin, AWT-489 did not act on the cyclooxygenases as a non-steroidal anti-inflammatory drug. Moreover, AWT-489 exhibited a better inhibitory effect than that of the well-used DP receptor antagonist, BWA868C when a dose close to the physiological concentration of PGD2 was used. These results suggest that AWT-489 can act as a novel human DP receptor antagonist to reduce the expression of CD55 in LS174T human colon cancer cells. We believe that AWT-489 has potential as a lead compound for designing a new DP receptor antagonist that may help improve PGD2-related diseases, especially colon cancer in the near future.
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Affiliation(s)
- Satomi Oyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
| | - Risa Yamazaki
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Iori Okura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
| | - Atsuko Awata
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba 263-8522, Japan
| | - Takayoshi Arai
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba 263-8522, Japan
| | - Toshihiko Murayama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
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12
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Yoshida K, Fujino H, Otake S, Seira N, Regan JW, Murayama T. Induction of cyclooxygenase-2 expression by prostaglandin E2 stimulation of the prostanoid EP4 receptor via coupling to Gαi and transactivation of the epidermal growth factor receptor in HCA-7 human colon cancer cells. Eur J Pharmacol 2013; 718:408-17. [DOI: 10.1016/j.ejphar.2013.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 07/17/2013] [Accepted: 08/14/2013] [Indexed: 11/28/2022]
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13
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Ji R, Sanchez CM, Chou CL, Chen XB, Woodward DF, Regan JW. Prostanoid EP₁ receptors mediate up-regulation of the orphan nuclear receptor Nurr1 by cAMP-independent activation of protein kinase A, CREB and NF-κB. Br J Pharmacol 2012; 166:1033-46. [PMID: 22188298 DOI: 10.1111/j.1476-5381.2011.01817.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Prostaglandin E(2) (PGE(2)) stimulation of the G protein-coupled prostanoid EP(1) receptor was found to up-regulate the expression of Nur-related factor 1 (Nurr1) (NR4A2), a transcription factor in the NR4A subfamily of nuclear receptors. The present studies characterize the molecular mechanism of this up-regulation. EXPERIMENTAL APPROACH The expression of Nurr1 was examined by immunoblot analysis, the polymerase chain reaction and reporter gene assays in human embryonic kidney (HEK) cells stably expressing the recombinant EP(1) receptor and in SH-SY5Y neuroblastoma cells expressing endogenous EP(1) receptors. Signalling pathway inhibitors were used to examine the roles of Rho, PKA, the cAMP response element binding protein (CREB) and NF-κB on the PGE(2) stimulated up-regulation of Nurr1. CREB and NF-κB signalling were also examined by immunoblot analysis and reporter gene assays. KEY RESULTS The EP(1) receptor mediated up-regulation of Nurr1 was blocked with inhibitors of Rho, PKA, NF-κB and CREB; but PGE(2) failed to significantly stimulate intracellular cAMP formation. PGE(2) stimulation of the EP1 receptor induced the phosphorylation and activation of CREB and NF-κB, which could be blocked by inhibition of PKA. CONCLUSIONS AND IMPLICATIONS PGE(2) stimulation of the human EP(1) receptor up-regulates the expression of Nurr1 by a mechanism involving the sequential activation of the Rho, PKA, CREB and NF-κB signalling pathways. EP(1) receptors are implicated in tumorigenesis and the up-regulation of Nurr1 may underlie the anti-apoptotic effects of PGE(2) .
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Affiliation(s)
- R Ji
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, USA
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14
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Sanchez CM, Gandolfi AJ, Regan JW. The Nurr1 transcription factor is upregulated by the EP1 prostanoid receptor in monomethylarsonous acid treated UROtsa cells. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.663.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christopher M. Sanchez
- Department of Pharmacology And ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - A. Jay Gandolfi
- Department of Pharmacology And ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - John W. Regan
- Department of Pharmacology And ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
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15
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Abstract
The potential for G-protein-coupled receptors (GPCRs) to show constitutive activity is emerging as one of the fundamental properties of GPCRs signal transduction. Indeed, of the four subtypes of E-type prostanoid (EP) receptors, the EP3 and EP4 subtypes show constitutive activity in addition to their innate ligand-dependent activation of signaling pathways. The constitutive activity of the EP3 and EP4 receptor subtypes was discovered during the initial characterizations of these receptors and may be important for setting the basal level of cellular tone in the given signaling pathway. This chapter introduces some of the methods that can be used to study the constitutive activity of the EP receptors.
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Affiliation(s)
- Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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16
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Chandramouli A, Mercado-Pimentel ME, Hutchinson A, Gibadulinová A, Olson ER, Dickinson S, Shañas R, Davenport J, Owens J, Bhattacharyya AK, Regan JW, Pastorekova S, Arumugam T, Logsdon CD, Nelson MA. The induction of S100p expression by the Prostaglandin E₂ (PGE₂)/EP4 receptor signaling pathway in colon cancer cells. Cancer Biol Ther 2010; 10:1056-66. [PMID: 20890108 DOI: 10.4161/cbt.10.10.13373] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Prostaglandin E₂ (PGE₂) levels are frequently elevated in colorectal carcinomas. PGE₂ is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptor is most relevant. PGE₂/EP4-receptor interaction activates CREB via the ERK/MEK pathway. However, the downstream target genes activated by this pathway remained to be investigated. METHODOLOGY/PRINICIPAL FINDINGS Here, we have identified S100P (an EF-hand calcium binding protein) as a novel downstream target. We show by realtime RT-PCR that S100P mRNA levels are elevated in 14/17 (82%) colon tumor tissues as compared to paired adjacent normal colonic tissues. S100P expression is stimulated in the presence of PGE₂ in a time dependent manner at mRNA and protein levels in colon, breast and pancreatic cancer cells. Pharmacological and RNAi-mediated inhibition of the EP4 receptor attenuates PGE₂-dependent S100P mRNA induction. RNA(i)-mediated knockdown of CREB inhibits endogenous S100P expression. Furthermore, using luciferase reporter analysis and EMSA we show that mutation and/or deletion of the CRE sequence within the S100P promoter abolished PGE₂-mediated transcriptional induction. Finally, we demonstrate that RNA(i)-mediated knockdown of S100P compromised invadopodia formation, colony growth and motility of colon cancer cells. Interestingly, endogenous knock down of S100P decreases ERK expression levels, suggesting a role for ERK in regulating S100P mediated cell growth and motility. CONCLUSIONS/SIGNIFICANCE Together, our findings show for the first time that S100P expression is regulated by PGE₂/EP4-receptor signaling and may participate in a feedback signaling that perpetuates tumor cell growth and migration. Therefore, our data suggest that dysregulated S100P expression resulting from aberrant PGE₂/EP4 receptor signaling may have important consequences relevant to colon cancer pathogenesis.
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17
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Fujino H, Toyomura K, Chen XB, Regan JW, Murayama T. Prostaglandin E₂ regulates cellular migration via induction of vascular endothelial growth factor receptor-1 in HCA-7 human colon cancer cells. Biochem Pharmacol 2010; 81:379-87. [PMID: 21070749 DOI: 10.1016/j.bcp.2010.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 11/01/2010] [Accepted: 11/02/2010] [Indexed: 01/03/2023]
Abstract
An important event in the development of tumors is angiogenesis, or the formation of new blood vessels. Angiogenesis is also known to be involved in tumor cell metastasis and is dependent upon the activity of the vascular endothelial growth factor (VEGF) signaling pathway. Studies of mice in which the EP3 prostanoid receptors have been genetically deleted have shown a role for these receptors in cancer growth and angiogenesis. In the present study, human colon cancer HCA-7 cells were used as a model system to understand the potential role of EP3 receptors in tumor cell migration. We now show that stimulation of HCA-7 cells with PGE₂ enhanced the up-regulation of VEGF receptor-1 (VEGFR-1) expression by a mechanism involving EP3 receptor-mediated activation of phosphatidylinositol 3-kinase and the extracellular signal-regulated kinases. Moreover, the PGE₂ stimulated increase in VEGFR-1 expression was accompanied by an increase in the cellular migration of HCA-7 cells. Given the known involvement of VEGFR-1 in cellular migration, our results suggest that EP3 receptors may contribute to tumor cell metastasis by increasing cellular migration through the up-regulation of VEGFR-1 signaling.
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Affiliation(s)
- Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Japan.
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18
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Salinthone S, Schillace RV, Tsang C, Regan JW, Bourdette DN, Carr DW. Lipoic acid stimulates cAMP production via G protein-coupled receptor-dependent and -independent mechanisms. J Nutr Biochem 2010; 22:681-90. [PMID: 21036588 DOI: 10.1016/j.jnutbio.2010.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 05/14/2010] [Accepted: 05/28/2010] [Indexed: 01/03/2023]
Abstract
Lipoic acid (LA) is a naturally occurring fatty acid that exhibits anti-oxidant and anti-inflammatory properties and is being pursued as a therapeutic for many diseases including multiple sclerosis, diabetic polyneuropathy and Alzheimer's disease. We previously reported on the novel finding that racemic LA (50:50 mixture of R-LA and S-LA) stimulates cAMP production, activates prostanoid EP2 and EP4 receptors and adenylyl cyclases (AC), and suppresses activation and cytotoxicity in NK cells. In this study, we present evidence that furthers our understanding of the mechanisms of action of LA. Using various LA derivatives, such as dihydrolipoic acid (DHLA), S,S-dimethyl lipoic acid (DMLA) and lipoamide (LPM), we discovered that only LA is capable of stimulating cAMP production in NK cells. Furthermore, there is no difference in cAMP production after stimulation with either R-LA, S-LA or racemic LA. Competition and synergistic studies indicate that LA may also activate AC independent of the EP2 and EP4 receptors. Pretreatment of PBMCs with KH7 (a specific peptide inhibitor of soluble AC) and the calcium inhibitor (Bapta) prior to LA treatment resulted in reduced cAMP levels, suggesting that soluble AC and calcium signaling mediate LA stimulation of cAMP production. In addition, pharmacological inhibitor studies demonstrate that LA also activates other G protein-coupled receptors, including histamine and adenosine but not the β-adrenergic receptors. These novel findings provide information to better understand the mechanisms of action of LA, which can help facilitate the use of LA as a therapeutic for various diseases.
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Affiliation(s)
- Sonemany Salinthone
- Portland Veterans Affairs Medical Center, Portland, OR 97239, USA; Department of Neurology, Oregon Health and Sciences University, Portland, OR 97239, USA
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19
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Hutchinson AJ, Coons SC, Chou CL, Xu W, Stamer WD, Woodward DF, Regan JW. Induction of Angiogenic Immediate Early Genes by Activation of FP Prostanoid Receptors in Cultured Human Ciliary Smooth Muscle Cells. Curr Eye Res 2010; 35:408-18. [PMID: 20450254 DOI: 10.3109/02713680903581021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
MESH Headings
- Actins/metabolism
- Blotting, Western
- Cells, Cultured
- Ciliary Body/drug effects
- Ciliary Body/embryology
- Ciliary Body/metabolism
- Connective Tissue Growth Factor/genetics
- Dinoprost/pharmacology
- Early Growth Response Protein 1/genetics
- Fluorescent Antibody Technique, Indirect
- Gene Expression Regulation/drug effects
- Genes, Immediate-Early/physiology
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Inositol Phosphates/metabolism
- Muscle, Smooth/drug effects
- Muscle, Smooth/embryology
- Muscle, Smooth/metabolism
- Neovascularization, Physiologic
- RNA, Messenger/metabolism
- Receptors, Prostaglandin/genetics
- Receptors, Prostaglandin/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
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20
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Ji R, Chou CL, Xu W, Chen XB, Woodward DF, Regan JW. EP1 prostanoid receptor coupling to G i/o up-regulates the expression of hypoxia-inducible factor-1 alpha through activation of a phosphoinositide-3 kinase signaling pathway. Mol Pharmacol 2010; 77:1025-36. [PMID: 20335389 DOI: 10.1124/mol.110.063933] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The EP1 prostanoid receptor is one of four subtypes whose cognate physiological ligand is prostaglandin-E2 (PGE(2)). It is in the family of G-protein-coupled receptors and is known to activate Ca(2+) signaling, although relatively little is known about other aspects of E-type prostanoid receptor (EP) 1 receptor signaling. In human embryonic kidney (HEK) cells expressing human EP1 receptors, we now show that PGE(2) stimulation of the EP1 receptor up-regulates the expression of hypoxia-inducible factor-1 alpha (HIF-1 alpha), which can be completely blocked by pertussis toxin, indicating coupling to G(i/o). This up-regulation of HIF-1 alpha occurs under normoxic conditions and could be inhibited with wortmannin, Akt inhibitor, and rapamycin, consistent with the activation of a phosphoinositide-3 kinase/Akt/mammalian target of rapamycin (mTOR) signaling pathway, respectively. In contrast to the hypoxia-induced up-regulation of HIF-1 alpha, which involves decreased protein degradation, the up-regulation of HIF-1 alpha by the EP1 receptor was associated with the phosphorylation of ribosomal protein S6 (rpS6), suggesting activation of the ribosomal S6 kinases and increased translation. Stimulation of endogenous EP1 receptors in human HepG2 hepatocellular carcinoma cells recapitulated the normoxic up-regulation of HIF-1 alpha observed in HEK cells, was sensitive to pertussis toxin, and involved the activation of mTOR signaling and phosphorylation of rpS6. In addition, treatment of HepG2 cells with sulprostone, an EP1-selective agonist, up-regulated the mRNA expression of vascular endothelial growth factor-C, a HIF-regulated gene. HIF-1 alpha is known to promote tumor growth and metastasis and is often up-regulated in cancer. Our findings provide a potential mechanism by which increased PGE(2) biosynthesis could up-regulate the expression of HIF-1 alpha and promote tumorigenesis.
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Affiliation(s)
- Ruyue Ji
- Department of Pharmacology and Toxicology, College of Pharmacy/The University of Arizona, 1703 E. Mabel St., Tucson, AZ 85721-0207, USA
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21
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Chen DC, Chou C, Hutchinson AJ, Regan JW. Prostaglandin F
2
α
(PGF
2
α
) stimulation of tumor necrosis factor‐α (TNF‐α) promoter activity by sequential activation of protein kinase C (PKC) and nuclear factor‐κB (NF‐κB) signaling. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.524.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Ji R, Chou C, Xu W, Regan JW. EP1 prostaoid receptor mediated upregulation of hypoxia inducible factor‐1
α
(HIF‐1
α
) under normoxic conditions by activation of Gi‐coupled phosphoinositide 3‐kinase (PI3K) signaling. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.581.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ruyue Ji
- pharmacology and toxicologyUniversity of ArizonaTucsonAZ
| | | | - Wei Xu
- pharmacology and toxicologyUniversity of ArizonaTucsonAZ
| | - John W Regan
- pharmacology and toxicologyUniversity of ArizonaTucsonAZ
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23
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Israel DD, Regan JW. EP(3) prostanoid receptor isoforms utilize distinct mechanisms to regulate ERK 1/2 activation. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:238-45. [PMID: 19416642 DOI: 10.1016/j.bbalip.2009.01.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 01/06/2009] [Accepted: 01/26/2009] [Indexed: 02/06/2023]
Abstract
Prostaglandin-E(2) (PGE(2)) is a hormone derived from the metabolism of arachidonic acid whose functions include regulation of platelet aggregation, fever and smooth muscle contraction/relaxation. PGE(2) mediates its physiological and pathophysiological effects through its binding to four G-protein coupled receptor subtypes, named EP(1), EP(2), EP(3) and EP(4). The EP(3) prostanoid receptor is unique in that it has multiple isoforms generated by alternative mRNA splicing. These splice variants display differences in tissue expression, constitutive activity and regulation of signaling molecules. To date there are few reports identifying differential activities of EP(3) receptor isoforms and their effects on gene regulation. We generated HEK cell lines expressing the human EP(3-Ia), EP(3-II) or EP(3-III) isoforms. Using immunoblot analysis we found that nM concentrations of PGE(2) strongly stimulated the phosphorylation of ERK 1/2 by the EP(3-II) and EP(3-III) isoforms; whereas, ERK 1/2 phosphorylation by the EP(3-Ia) isoform was minimal and only occurred at muM concentrations of PGE(2). Furthermore, the mechanisms of the PGE(2) mediated phosphorylation of ERK 1/2 by the EP(3-II) and EP(3-III) isoforms were different. Thus, PGE(2) stimulation of ERK 1/2 phosphorylation by the EP(3-III) isoform involves activation of a Galpha(i)/PI3K/PKC/Src and EGFR-dependent pathway; while for the EP(3-II) isoform it involves activation of a Galpha(i)/Src and EGFR-dependent pathway. These differences result in unique differences in the regulation of reporter plasmid activity for the downstream effectors ELK1 and AP-1 by the EP(3-II) and EP(3-III) prostanoid receptor isoforms.
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Affiliation(s)
- Davelene D Israel
- Department of Pharmacology and Toxicology, The University of Arizona, College of Pharmacy, 1703 E. Mabel St., Tucson, AZ 85721, USA
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24
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Hutchinson AJ, Chou CL, Israel DD, Xu W, Regan JW. Activation of EP2 prostanoid receptors in human glial cell lines stimulates the secretion of BDNF. Neurochem Int 2009; 54:439-46. [PMID: 19428786 DOI: 10.1016/j.neuint.2009.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 12/27/2008] [Accepted: 01/22/2009] [Indexed: 10/21/2022]
Abstract
Prostaglandin E(2) (PGE(2)) is produced at high levels in the injured central nervous system, where it is generally considered a cytotoxic mediator of inflammation. The cellular actions of PGE(2) are mediated by G-protein signaling activated by prostanoid receptors termed EP(1), EP(2), EP(3) and EP(4). Recent studies have implicated the EP(2) prostanoid receptor to be in apparently conflicting roles promoting neuronal death in some model systems and the survival of neurons in others. Here we show that treatment of immortalized human microglia and CCF-STTG1 astrocytes with either PGE(2) or the EP(2) selective agonist butaprost stimulates the release of brain-derived neurotrophic factor (BDNF). Both cell lines express mRNA for the EP(2) receptor, whereas transcripts for the other subtypes are not detected. Pharmacological studies using PGE(2) and modulators of cyclic AMP signaling implicate this pathway in PGE(2)-stimulated BDNF release. These results indicate that EP(2) prostanoid receptor activation induces BDNF secretion through stimulation of cyclic AMP dependent signaling. Our findings provide a mechanism by which endogenous PGE(2) might contribute to either neurotoxicity or neuroprotection in the injured brain via the induction of BDNF release from microglial cells and astrocytes.
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Affiliation(s)
- Anthony J Hutchinson
- Program in Neuroscience, The University of Arizona, College of Pharmacy, Gould-Simpson 611, PO Box 210077, Tucson, AZ 85721, USA
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25
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Israel DD, Xu W, Chou C, Hutchinson A, Regan JW. Crosstalk between Ras/Raf and Tcf signaling following stimulation of the FP prostanoid receptor by prostaglandin‐F2alpha (PGF2a). FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.908.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Wei Xu
- Department of Pharmacology/Toxicology
| | | | | | - John W Regan
- Program in NeuroscienceUniversity of ArizonaTucsonAZ
- Department of Pharmacology/Toxicology
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26
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Ji R, Chen X, Regan JW. Induction of Orphan Nuclear Receptor Nurr1 Expression by the Human EP
1
Prostanoid Receptors. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.723.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ruyue Ji
- Pharmacology & ToxicologyU of ATucsonAZ
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Hutchinson A, Chou C, Israel D, Xu W, Regan JW. Prostaglandin E2 (PGE2) stimulates the secretion of brain‐derived neurotrophic factor (BDNF) from cultured human microglia. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.729.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Chih‐Ling Chou
- Department of Pharmacology & ToxicologyUniversity of ArizonaTucsonAZ
| | - Davelene Israel
- Department of Pharmacology & ToxicologyUniversity of ArizonaTucsonAZ
| | - Wei Xu
- Department of Pharmacology & ToxicologyUniversity of ArizonaTucsonAZ
| | - John W. Regan
- Program in Neuroscience
- Department of Pharmacology & ToxicologyUniversity of ArizonaTucsonAZ
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28
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Hao W, Chou C, Xu W, Israel D, Hutchinson A, Ji R, Regan JW. The TCF‐4 signaling pathway negatively regulates HIF‐1a transcriptional activity in response to hypoxia. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.829.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Wei Hao
- Biochemsitry and Molecular Biophysics
| | - Chih‐Ling Chou
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - Wei Xu
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - Davelene Israel
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - Anthony Hutchinson
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - Ruyue Ji
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
| | - John W. Regan
- Pharmacology and ToxicologyCollege of PharmacyUniversity of ArizonaTucsonAZ
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29
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Chou C, Xu W, Hutchinson AJ, Israel DD, Regan JW. Human FP prostanoid receptors regulate HIF‐1α through activation of a ROS mediated non‐canonical Wnt signaling pathway. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.909.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Wei Xu
- Pharmacology & ToxicologyCollege of Pharmacy
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30
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Xu W, Chou CL, Sun H, Fujino H, Chen QM, Regan JW. FP prostanoid receptor-mediated induction of the expression of early growth response factor-1 by activation of a Ras/Raf/mitogen-activated protein kinase signaling cascade. Mol Pharmacol 2007; 73:111-8. [PMID: 17911534 DOI: 10.1124/mol.107.038778] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
FP prostanoid receptors are G-protein-coupled receptors whose physiological activator is prostaglandin-F(2alpha) (PGF(2alpha)). PGF(2alpha) has been implicated in wound healing and cardiac hypertrophy, which are both known to involve the induction of the immediate-early response gene, early growth response factor-1 (EGR-1). We hypothesized that activation of the human FP receptor by PGF(2alpha) could induce the expression of EGR-1 and found that 1 muM PGF(2alpha) produced a time-dependent induction of both mRNA and protein expression for EGR-1. This FP receptor-mediated induction of EGR-1 expression involved activation of the small GTPase Ras followed by activation of C-Raf and the mitogen-activated protein (MAP) kinase kinases 1 and 2 (MEK1/2). Thus, induction of EGR-1 expression by PGF(2alpha) was blocked using dominant-negative constructs of Ras and C-Raf and the Raf kinase inhibitor 4-(4-(3-(4-chloro-3-trifluoromethylphenyl)ureido)phenoxy)-pyridine-2-carboxyllic acid methyamide-4-methylbenzenesulfonate (BAY43-9006). Likewise, the MEK1/2 inhibitor 2'-amino-3'-methoxyflavone (PD98059) blocked the induction of EGR-1 expression by PGF(2alpha). FP receptor stimulation by PGF(2alpha) induced the phosphorylation of C-Raf, MEK1/2, and extracellular signal-regulated kinases 1 and 2, consistent with the activation of a MAP kinase signaling cascade. PGF(2alpha) was also found to induce the expression of EGR-1 in rat cardiomyocytes through the activation of endogenous FP receptors. This induction of EGR-1 expression in cardiomyocytes also involved the activation of Raf and MAP kinase signaling and was dependent on the activation of protein kinase C. This is the first report to show the regulation of EGR-1 expression after PGF(2alpha) activation of FP receptors and suggests that this could be an early event involved in wound healing and cardiac hypertrophy.
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Affiliation(s)
- Wei Xu
- Department of Pharmacology and Toxicology, College of Pharmacy/The University of Arizona, 1703 E. Mabel St., Tucson, AZ 85721-0207, USA
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31
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Cherukuri DP, Chen XBO, Goulet AC, Young RN, Han Y, Heimark RL, Regan JW, Meuillet E, Nelson MA. The EP4 receptor antagonist, L-161,982, blocks prostaglandin E2-induced signal transduction and cell proliferation in HCA-7 colon cancer cells. Exp Cell Res 2007; 313:2969-79. [PMID: 17631291 PMCID: PMC2706013 DOI: 10.1016/j.yexcr.2007.06.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 02/07/2023]
Abstract
Accumulating evidence indicates that elevated levels of prostaglandin E(2) (PGE(2)) can increase intestinal epithelial cell proliferation, and thus play a role in colorectal tumorigenesis. PGE(2) exerts its effects through four G-protein-coupled PGE receptor (EP) subtypes, named the EP1, EP2, EP3, and EP4. Increased phosphorylation of extracellular regulated kinases (ERK1/2) is required for PGE(2) to stimulate cell proliferation of human colon cancer cells. However, the EP receptor(s) that are involved in this process remain unknown. We provide evidence that L-161,982, a selective EP4 receptor antagonist, completely blocks PGE(2)-induced ERK phosphorylation and cell proliferation of HCA-7 cells. In order to identify downstream target genes of ERK1/2 signaling, we found that PGE(2) induces expression of early growth response gene-1 (EGR-1) downstream of ERK1/2 and regulates its expression at the level of transcription. PGE(2) treatment induces phosphorylation of cyclic AMP response element binding protein (CREB) at Ser133 residue and CRE-mediated luciferase activity in HCA-7 cells. Studies with dominant-negative CREB mutant (ACREB) provide clear evidence for the involvement of CREB in PGE(2) driven egr-1 transcription in HCA-7 cells. In conclusion, this study reveals that egr-1 is a target gene of PGE(2) in HCA-7 cells and is regulated via the newly identified EP4/ERK/CREB pathway. Finally our results support the notion that antagonizing EP4 receptors may provide a novel therapeutic approach to the treatment of colon cancer.
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Affiliation(s)
| | - Xiao BO Chen
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ
| | | | | | - Yongxin Han
- Merck Frosst Centre for Therapeutic Research, Canada
| | | | - John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ
| | | | - Mark A Nelson
- Department of Pathology, Arizona Cancer Center, University of Arizona, Tucson, AZ
- Corresponding author: Mark A Nelson, Ph.D. Professor and Director of Research; 1501N Campbell Ave, # 550, Tucson, AZ 85724. Tel: 520.626.2619; Fax: 520.626.8864; E-mail:
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32
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Fujino H, Chen XB, Regan JW, Murayama T. Indomethacin decreases EP2 prostanoid receptor expression in colon cancer cells. Biochem Biophys Res Commun 2007; 359:568-73. [PMID: 17555711 PMCID: PMC2674506 DOI: 10.1016/j.bbrc.2007.05.145] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 05/19/2007] [Indexed: 01/30/2023]
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) can decrease the risk of colorectal cancer; however, it has not been established if this effect is solely through their ability to inhibit cyclooxygenase (COX). In this study the effects of indomethacin, a potent NSAID and nonselective COX inhibitor, was examined in LS174T human colon cancer cells. These cells were found to express EP2 prostanoid receptors, but not the EP1, EP3 or EP4 subtypes. Pretreatment of LS174T cells with indomethacin produced a complete inhibition of prostaglandin E(2) (PGE(2)) stimulated cyclic AMP (cAMP) formation in a dose dependent manner with an IC(50) of 21 microM. Interestingly, the inhibition of PGE(2)-stimulated cAMP formation by indomethacin was accompanied by a decrease in EP2 mRNA expression and by a decrease in the whole cell specific binding of [(3)H]PGE(2). Thus, treatment of LS174T cells with indomethacin causes a down regulation of EP2 prostanoid receptors expression that may be independent of COX inhibition.
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MESH Headings
- Cell Line, Tumor
- Colforsin/pharmacology
- Colonic Neoplasms/genetics
- Colonic Neoplasms/metabolism
- Cyclic AMP/biosynthesis
- Dinoprostone/pharmacology
- Down-Regulation/drug effects
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Indomethacin/pharmacology
- RNA, Messenger/genetics
- Receptors, Prostaglandin E/genetics
- Receptors, Prostaglandin E/metabolism
- Receptors, Prostaglandin E, EP2 Subtype
- Receptors, Prostaglandin E, EP3 Subtype
- Receptors, Prostaglandin E, EP4 Subtype
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Affiliation(s)
- Hiromichi Fujino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan.
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33
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Wada M, DeLong CJ, Hong YH, Rieke CJ, Song I, Sidhu RS, Yuan C, Warnock M, Schmaier AH, Yokoyama C, Smyth EM, Wilson SJ, FitzGerald GA, Garavito RM, Sui DX, Regan JW, Smith WL. Enzymes and receptors of prostaglandin pathways with arachidonic acid-derived versus eicosapentaenoic acid-derived substrates and products. J Biol Chem 2007; 282:22254-66. [PMID: 17519235 DOI: 10.1074/jbc.m703169200] [Citation(s) in RCA: 282] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Dietary fish oil containing omega 3 highly unsaturated fatty acids has cardioprotective and anti-inflammatory effects. Prostaglandins (PGs) and thromboxanes are produced in vivo both from the omega 6 fatty acid arachidonic acid (AA) and the omega 3 fatty acid eicosapentaenoic acid (EPA). Certain beneficial effects of fish oil may result from altered PG metabolism resulting from increases in the EPA/AA ratios of precursor phospholipids. Here we report in vitro specificities of prostanoid enzymes and receptors toward EPA-derived, 3-series versus AA-derived, 2-series prostanoid substrates and products. The largest difference was seen with PG endoperoxide H synthase (PGHS)-1. Under optimal conditions purified PGHS-1 oxygenates EPA with only 10% of the efficiency of AA, and EPA significantly inhibits AA oxygenation by PGHS-1. Two- to 3-fold higher activities or potencies with 2-series versus 3-series compounds were observed with PGHS-2, PGD synthases, microsomal PGE synthase-1 and EP1, EP2, EP3, and FP receptors. Our most surprising observation was that AA oxygenation by PGHS-2 is only modestly inhibited by EPA (i.e. PGHS-2 exhibits a marked preference for AA when EPA and AA are tested together). Also unexpectedly, TxA(3) is about equipotent to TxA(2) at the TP alpha receptor. Our biochemical data predict that increasing phospholipid EPA/AA ratios in cells would dampen prostanoid signaling with the largest effects being on PGHS-1 pathways involving PGD, PGE, and PGF. Production of 2-series prostanoids from AA by PGHS-2 would be expected to decrease in proportion to the compensatory decrease in the AA content of phospholipids that would result from increased incorporation of omega 3 fatty acids such as EPA.
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Affiliation(s)
- Masayuki Wada
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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34
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Israel DD, Regan JW. Differential signaling pathway activation and gene regulation among three human prostaglandin E3 (EP3) receptors. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - John W Regan
- Pharmacology/ToxicologyUniversity of Arizona1703 E. Mabel StreetTucsonAZ85721
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Abstract
The EP(2) and EP(4) prostanoid receptor subtypes are G-protein-coupled receptors for prostaglandin E(2) (PGE(2)). Both receptor subtypes are known to couple to the stimulatory guanine nucleotide binding protein (Galpha(s)) and, after stimulation with PGE(2), can increase the formation of intracellular cAMP. In addition, PGE(2) stimulation of the EP(4) receptor can activate phosphatidylinositol 3-kinase (PI3K) leading to phosphorylation of the extracellular signal-regulated kinases (ERKs) and induction of early growth response factor-1 (EGR-1). We now report that the PGE(2)-mediated phosphorylation of the ERKs and induction of EGR-1 can be blocked by pretreatment of EP(4)-expressing cells with pertussis toxin (PTX). Furthermore, pretreatment with PTX increased the amount of PGE(2)-stimulated intracellular cAMP formation in EP(4)-expressing cells but not in EP(2)-expressing cells. These data indicate that the EP(4) prostanoid receptor subtype, but not the EP(2), couples to a PTX-sensitive inhibitory G-protein (Galpha(i)) that can inhibit cAMP-dependent signaling and activate PI3K/ERK-dependent signaling.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
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36
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Fujino H, Salvi S, Regan JW. Differential regulation of phosphorylation of the cAMP response element-binding protein after activation of EP2 and EP4 prostanoid receptors by prostaglandin E2. Mol Pharmacol 2005; 68:251-9. [PMID: 15855407 DOI: 10.1124/mol.105.011833] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The EP2 and EP4 prostanoid receptors are G-protein-coupled receptors whose activation by their endogenous ligand, prostaglandin (PG) E2, stimulates the formation of intracellular cAMP. We have previously reported that the stimulation of cAMP formation in EP4-expressing cells is significantly less than in EP2-expressing cells, despite nearly identical levels of receptor expression (J Biol Chem 277:2614-2619, 2002). In addition, a component of EP4 receptor signaling, but not of EP2 receptor signaling, was found to involve the activation of phosphatidylinositol 3-kinase (PI3K). In this study, we report that PGE2 stimulation of cells expressing either the EP2 or EP4 receptor results in the phosphorylation of the cAMP response element binding protein (CREB) at serine-133. Pretreatment of cells with N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H-89), an inhibitor of protein kinase A (PKA), attenuated the PGE2-mediated phosphorylation of CREB in EP2-expressing cells, but not in EP4-expressing cells. Pretreatment of cells with wortmannin, an inhibitor of PI3K, had no effects on the PGE2-mediated phosphorylation of CREB in either EP2- or EP4-expressing cells, although it significantly increased the PGE2-mediated activation of PKA in EP4-expressing cells. However, combined pretreatment with H-89 and wortmannin blocked PGE2-mediated phosphorylation in EP2-expressing cells as well as in EP2-expressing cells. PGE2-mediated intracellular cAMP formation was not affected by pretreatment with wortmannin, or combined treatment with wortmannin and H-89, in either the EP2- or EP4-expressing cells. These findings suggest that PGE2 stimulation of EP4 receptors, but not EP2 receptors, results in the activation of a PI3K signaling pathway that inhibits the activity of PKA and that the PGE2-mediated phosphorylation of CREB by these receptors occurs through different signaling pathways
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721-0207, USA
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37
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Fujino H, Vielhauer GA, Regan JW. Prostaglandin E2 selectively antagonizes prostaglandin F2alpha-stimulated T-cell factor/beta-catenin signaling pathway by the FPB prostanoid receptor. J Biol Chem 2004; 279:43386-91. [PMID: 15280380 DOI: 10.1074/jbc.m408276200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FP prostanoid receptors are G-protein-coupled receptors that consist of two isoforms named FPA and FPB. Both isoforms activate inositol phosphate second messenger signaling pathways by their endogenous ligand prostaglandin F2alpha (PGF2alpha). Previously we have shown that both isoforms undergo Rho-mediated cell rounding following treatment with PGF2alpha. Following the removal of PGF2alpha, however, FPA-expressing cells return to their original morphology, whereas FPB-expressing cells do not. It was also found that PGF2alpha-could activate T-cell factor (Tcf)/beta-catenin signaling in cells expressing the FPB isoform but not in cells expressing the FPA isoform. We now show that prostaglandin E2 (PGE2) can induce cell rounding and stimulate the formation of inositol phosphates to the same extent as PGF2alpha in cells expressing either the FPA or FPB isoforms. However, PGE2 has much lower efficacy as compared with PGF2alpha for the activation of Tcf/beta-catenin signaling in FPB-expressing cells, and the cell rounding is reversible. Interestingly, pretreatment of FPB-expressing cells with PGE2-attenuated PGF2alpha-stimulated Tcf/beta-catenin signaling in a dose-dependent manner while having no effect on PGF2alpha-stimulated inositol phosphates formation. Thus, the ratio of endogenous PGE2 and PGF2alpha has the potential to selectively regulate one signaling pathway over another. This represents a novel mechanism for the regulation of cell signaling that is distinct from regulation occurring at the level of the receptor and its effector pathways.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson 85721-0207, USA
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38
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Fujino H, Regan JW. Prostaglandin F2α amplifies tumor necrosis factor-α promoter activity by the FPB prostanoid receptor. Biochem Biophys Res Commun 2004; 317:1114-20. [PMID: 15094384 DOI: 10.1016/j.bbrc.2004.03.167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Indexed: 11/23/2022]
Abstract
This study examines the regulation of tumor necrosis factor-alpha (TNF-alpha) promoter activity by prostaglandin F2alpha ( PGF2alpha ) in HEK cells stably expressing either the FPA or FPB prostanoid receptors. Cells were transiently transfected with a luciferase reporter plasmid under the control of a TNF-alpha promoter and luciferase activity was measured. In the absence of PGF2alpha basal TNF-alpha reporter gene activity is elevated in FPB cells as compared with FPA cells. This elevated basal activity is blocked by pretreatment with a Rho inhibitor, but not by pretreatment with an inhibitor of protein kinase C (PKC). TNF-alpha reporter activity in FPB cells is stimulated by PGF2alpha and this is decreased by pretreatment with a chelator of intracellular calcium or by a gap junction inhibitor. In FPB cells pretreatment with a Rho inhibitor combined with either a calcium chelator or a gap junction inhibitor decreases both basal and PGF2alpha stimulated TNF-alpha reporter activity. Interestingly post-treatment of FPB cells with an inhibitor of PKC decreased PGF2alpha stimulated TNF-alpha reporter gene activity even though pretreatment did not. It, therefore, appears that PGF2alpha stimulated TNF-alpha reporter activity in FPB cells is amplified by a Rho-dependent mechanism involving calcium, gap junctions, and PKC. These findings may help in understanding the function of the FPB isoform in the corpus luteum.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
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39
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Abstract
The EP(2) and EP(4) prostanoid receptors are two of the four subtypes of receptors for prostaglandin E(2) (PGE(2)). They are in the family of G-protein coupled receptors and both receptors were initially characterized as coupling to Gs and increasing intracellular cAMP formation. Recently, however, we have shown that both receptors can stimulate T-cell factor (Tcf) mediated transcriptional activity. The EP(2) receptor does this primarily through cAMP-dependent protein kinase (PKA), whereas the EP(4) utilizes phosphatidylinositol 3-kinase (PI3K) as well as PKA. In addition, we have shown that the EP(4) receptor, but not the EP(2), can activate the extracellular signal-regulated kinases (ERKs) 1 and 2 by way of PI3K leading to the induction of early growth response factor-1 (EGR-1), a transcription factor traditionally associated with wound healing. This induction of EGR-1 expression has significant implications concerning the potential role of PGE(2) in cancer and inflammatory disorders.
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Affiliation(s)
- John W Regan
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721-0207, USA.
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40
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Vielhauer GA, Fujino H, Regan JW. Cloning and localization of hFPS: a six-transmembrane mRNA splice variant of the human FP prostanoid receptor. Arch Biochem Biophys 2004; 421:175-85. [PMID: 14984197 DOI: 10.1016/j.abb.2003.10.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
FP prostanoid receptors are G-protein coupled receptors that mediate the actions of prostaglandin F2alpha. Two isoforms, designated FP(A) and FP(B), have been previously described. We now report the cloning of a FP receptor mRNA alternative splice variant from human heart and placenta cDNA, named hFP(S). The cDNA encoding hFP(S) has a 71 bp insert that produces a frame shift resulting in a truncated receptor lacking transmembrane-7 and the intracellular carboxyl tail. This 71 bp sequence has been identified as a distinct exon localized in the human FP receptor gene on chromosome one. Northern blot analysis suggests that hFPs is expressed in skeletal muscle as well as human heart and placenta. Immunohistochemical microscopy showed positive immunoreactivity on vascular endothelial, trophoblast, and decidual cells from human placenta. hFPs represents the first confirmed alternative splice variant of the human FP prostanoid receptor gene, however, its function is presently unknown.
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Affiliation(s)
- George A Vielhauer
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
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41
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721-0207, USA
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42
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Fujino H, Xu W, Regan JW. Prostaglandin E2 induced functional expression of early growth response factor-1 by EP4, but not EP2, prostanoid receptors via the phosphatidylinositol 3-kinase and extracellular signal-regulated kinases. J Biol Chem 2003; 278:12151-6. [PMID: 12566441 DOI: 10.1074/jbc.m212665200] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prostaglandin E(2) (PGE(2)) mediates its physiological effects by interactions with a subfamily of G-protein-coupled receptors known as EP receptors. These receptors consist of four primary subtypes named EP(1), EP(2), EP(3), and EP(4). The EP(2) and EP(4) subtypes are known to couple to Galpha(s) and stimulate intracellular cyclic 3,5- adenosine monophosphate formation, whereas the EP(1) and EP(3) receptors are known to couple to Galpha(q) and Galpha(i), respectively. Recently we found that EP(2) and EP(4) receptors can activate T-cell factor signaling; however, EP(2) receptors did this primarily through a cAMP-dependent protein kinase-dependent pathway, whereas EP(4) receptors primarily utilized a phosphatidylinositol 3-kinase (PI3K)-dependent pathway (Fujino, H., West, K. A., and Regan, J. W. (2002) J. Biol. Chem. 277, 2614-2619). We now report that PGE(2) stimulation of EP(4) receptors, but not EP(2) receptors, leads to phosphorylation of the extracellular signal-regulated kinases (ERKs) through a PI3K-dependent mechanism. Furthermore, this activation of PI3K/ERK signaling by the EP(4) receptors induces the functional expression of early growth response factor-1 (EGR-1). Under the same conditions induction of EGR-1 protein expression was not observed following PGE(2) stimulation of EP(2) receptors. These findings point to important differences in the signaling potential of the EP(2) and EP(4) receptors, which could be significant with respect to the potential involvement of EP(4) receptors in inflammation and cancer.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721-0207, USA
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43
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Abstract
We have recently shown that the FP(B) prostanoid receptor activates beta-catenin signaling through the activation of Rho in human embryo kidney (HEK)-293 cells stably expressing the FP(B) receptors. We now report that the FP(B) receptor can stimulate cyclooxygenase-2 promoter activity and may, therefore, regulate the expression of cyclooxygenase-2. This stimulation of cyclooxygenase-2 promoter activity is blocked by pretreatment with an inhibitor of Rho, but not with an inhibitor of protein kinase C (PKC). Potential up regulation of cyclooxygenase-2 expression by the FP(B) receptor would establish a positive feedback loop that would drive beta-catenin signaling and could be involved in cancer.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
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44
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Porter AC, Svensson SPS, Stamer WD, Bahl JJ, Richman JG, Regan JW. Alpha-2 adrenergic receptors stimulate actin organization in developing fetal rat cardiac myocytes. Life Sci 2003; 72:1455-66. [PMID: 12535714 DOI: 10.1016/s0024-3205(02)02381-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Expression of alpha(2)-adrenergic receptors (alpha(2)-AR) is very high in fetal rat heart although numbers decline with increasing gestational age. The current experiments were designed to identify the subtypes of alpha(2)-AR expressed and the function of these receptors in fetal cardiac myocytes. Expression of alpha(2)A and alpha(2)C, but not alpha(2)B, was confirmed in the myocyte population by indirect immunofluorescence microscopy with subtype-specific antibodies and by Western blot. Both dexmedetomidine, an alpha(2)-selective agonist, and norepinephrine, increased actin cytoskeleton organization and this increase was blocked by the alpha(2)-selective antagonist, atipamezole. Furthermore, dexmedetomidine inhibited isoproterenol-stimulated cAMP accumulation in isolated fetal rat heart and this was blocked by rauwolscine. Therefore, functional alpha(2)A and alpha(2)B subtypes are present in the fetal rat heart where they may have a role in cardiac development.
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Affiliation(s)
- Amy C Porter
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721, USA.
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Abstract
FP prostanoid receptors have been identified as two isoforms named FP(A) and FP(B). We have shown that the FP(B) isoform, but not the FP(A), activates beta-catenin-mediated transcription. We now report that the mechanism of this FP(B)-specific activation of beta-catenin signaling occurs in two steps. The first is a conditioning step that involves an agonist-independent association of the FP(B) receptor with phosphatidylinositol 3-kinase followed by constitutive internalization of a receptor complex containing E-cadherin and beta-catenin. This constitutive internalization conditions the cell for subsequent beta-catenin signaling by increasing the cellular content of cytosolic beta-catenin. The second step involves agonist-dependent activation of Rho followed by cell rounding. Because of the conditioning step, this agonist-dependent step results in a stabilization of beta-catenin and activation of transcription. Although stimulation of the FP(A) isoform activates Rho and induces cellular shape change, it does not activate beta-catenin signaling, because the FP(A) does not undergo constitutive internalization and does not condition the cell for beta-catenin signaling. The cellular conditioning described here for the FP(B) illustrates the potential of the receptor to alter the signaling environment of a cell even in the absence of agonist and has general significance for understanding G-protein-coupled receptor signaling.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson 85721-0207, USA
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Weber TJ, Markillie LM, Chrisler WB, Vielhauer GA, Regan JW. Modulation of JB6 mouse epidermal cell transformation response by the prostaglandin F2alpha receptor. Mol Carcinog 2002; 35:163-72. [PMID: 12489107 DOI: 10.1002/mc.10079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Prostaglandin F(2alpha) (PGF(2alpha)) modulates clonal selection processes in the mouse skin model of carcinogenesis. In this study we investigated whether JB6 mouse epidermal cells expressed a functional PGF(2alpha) receptor (FP) coupled with a cell-transformation response. Treatment of JB6 cells with an FP agonist (fluprostenol) potently (pM-nM) increased anchorage-dependent and anchorage-independent growth. Inositol phospholipid accumulation and extracellular signal-regulated kinase (Erk) activity were increased in cells treated with FP agonists, consistent with established FP-related signal transduction. FP mRNA was detected by reverse transcription-polymerase chain reaction, and the average specific [(3)H]PGF(2alpha) binding was 8.25 +/- 0.95 fmol/mg protein. Erk activity and colony size were increased by cotreatment of JB6 cells with epidermal growth factor (EGF) and fluprostenol to a greater extent than with either treatment alone, whereas the cotreatment effect on colony number appeared to be simply additive. Collectively, our data indicated that JB6 cells expressed a functional FP coupled with transformation-related signal transduction and the regulation of clonal selection processes. Erk activity appears to be a convergence point in the EGF and FP pathways. The data raise the possibility that the FP contributes to clonal selection processes but probably plays a more important role as a response modifier.
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Affiliation(s)
- Thomas J Weber
- Molecular Biosciences, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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Srinivasan D, Fujino H, Regan JW. Differential internalization of the prostaglandin f(2alpha) receptor isoforms: role of protein kinase C and clathrin. J Pharmacol Exp Ther 2002; 302:219-24. [PMID: 12065720 DOI: 10.1124/jpet.302.1.219] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
FP prostanoid receptors are G-protein-coupled receptors that mediate the actions of prostaglandin F(2alpha) (PGF(2alpha)). Alternative mRNA splicing gives rise to two isoforms, FP(A) and FP(B), which are identical except for their intracellular carboxyl termini. In this study, we examined the internalization of recombinant FLAG-epitope-tagged FP(A) and FP(B) receptors that were stably expressed in human embryonic kidney-293 cells. Cell surface receptors on live cells were labeled with anti-FLAG antibodies either in the presence or absence of PGF(2alpha) and were examined by immunofluorescence microscopy. In the absence of PGF(2alpha), FP(A)-expressing cells were labeled predominantly on the cell surface; however, FP(B)-expressing cells were labeled on both the cell surface and intracellularly, indicating constitutive internalization of the FP(B) isoform. After treatment with PGF(2alpha), FP(A)-expressing cells were labeled intracellularly, reflecting receptor internalization, which could be mimicked with phorbol 12-myristyl 13-acetate (PMA), an activator of protein kinase C (PKC). Pretreatment of FP(A)-expressing cells with Gö 6976 [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo[2,3-a]pyrrolo[3,4-c]carbozole], an inhibitor of PKC, blocked both PGF(2alpha)- and PMA-induced receptor internalization. However, Gö 6976 did not block constitutive internalization of the FP(B) isoform, suggesting that the mechanisms of receptor internalization differ between the FP(A) and FP(B) isoforms. Furthermore, pretreatment with sucrose, an inhibitor of clathrin-dependent internalization, blocked PGF(2alpha)-induced internalization of the FP(A) isoform but did not block constitutive internalization of the FP(B) isoform. In conclusion, the FP(A) receptor isoform shows an agonist-induced internalization involving PKC and clathrin, whereas the FP(B) isoform undergoes agonist-independent internalization that does not involve PKC or clathrin.
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Affiliation(s)
- Dinesh Srinivasan
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721-0207, USA
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Anthony TL, Fujino H, Pierce KL, Yool AJ, Regan JW. Differential regulation of Ca(2+)-dependent Cl- currents by FP prostanoid receptor isoforms in Xenopus oocytes. Biochem Pharmacol 2002; 63:1797-806. [PMID: 12034364 DOI: 10.1016/s0006-2952(02)00953-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The FP(A) and FP(B) prostanoid receptor isoforms are G-protein-coupled receptors that are activated by prostaglandin F(2alpha) (PGF(2alpha)). Differences in their carboxyl termini prompted us to examine the intracellular calcium (Ca(2+)) signaling of these receptor isoforms using the Xenopus oocyte expression system. Protein expression was determined by immunofluorescence microscopy and whole cell binding with [3H]PGF(2alpha). Positive immunolabeling was observed on the outer membranes of oocytes expressing FLAG-tagged FP receptor isoforms, but not on control (water-injected) oocytes. Intracellular signaling was examined using a two-electrode voltage clamp. Specific whole-cell binding was also detected for both receptor isoforms. Bath application of 10 microM PGF(2alpha) to FP(A)-expressing oocytes produced a chloride (Cl-) current response similar to that of an injection of inositol 1,4,5-trisphosphate (InsP(3)) (5.76+/-0.6 microA, peak current; N=23) that returned to control levels within 25 min. In FP(B)-expressing oocytes the activation of the Cl- current was delayed or completely absent (1.38+/-0.2 microA, peak current; N=18). Control oocytes were not responsive to the application of PGF(2alpha) (0.87+/-0.1 microA, peak current; N=10). Activation of Cl- currents for both FP receptor isoforms was dependent upon intracellular Ca(2+) stores as a 30-min pretreatment with thapsigargin (1 microM; N=5) blocked the PGF(2alpha) induction of the Cl- current. These data indicate that the FP prostanoid receptor isoforms differ in their ability to activate Ca(2+)-dependent Cl- channels when expressed in Xenopus oocytes. The difference appears to be in the ability of the two FP prostanoid receptor isoforms to mobilize intracellular calcium.
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Affiliation(s)
- Todd L Anthony
- Glaucoma Center, Department of Ophthalmology, University of California at San Diego, La Jolla, CA 92037, USA.
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Huang Y, Stamer WD, Anthony TL, Kumar DV, St John PA, Regan JW. Expression of alpha(2)-adrenergic receptor subtypes in prenatal rat spinal cord. Brain Res Dev Brain Res 2002; 133:93-104. [PMID: 11882340 DOI: 10.1016/s0165-3806(02)00275-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The results of molecular cloning have revealed three subtypes of the alpha(2)-adrenergic receptors (alpha(2) AR) that have been defined alpha(2)C10 (alpha(2A)), alpha(2)C2 (alpha(2B)) and alpha(2)C4 (alpha(2C)). The differential expression of alpha(2) AR subtypes is affected by developmental factors in rat submandibular gland, lung and brain. In the spinal cord of postnatal and adult rats, alpha(2A) and alpha(2C) AR subtypes are expressed and appear to mediate pain perception. However, the relative expression of alpha(2) AR subtypes in the prenatal spinal cord is unknown. In the present study subtype-specific antibodies and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine the expression and localization of the alpha(2) AR subtypes in sections of embryonic day 14 rat spinal cords and primary cultures of cells isolated from these cords. Spinal cords were removed from day 14 embryos, and were sectioned or used for the preparation of cell cultures. After 9 days in culture, neurons were examined by immunofluorescence microscopy or used for preparation of total RNA. In both intact spinal cords and isolated cells, positive immunoreactivity was detected with antibodies against alpha(2A) and alpha(2B) subtypes, but not with antibodies against the alpha(2C) subtype. Using a dual-labeling approach, anti-alpha(2A) and anti-alpha(2B) immunoreactivity was present on the same population of neurons. RT-PCR results were consistent with immunofluorescence studies, and showed that mRNA encoding the alpha(2A) and alpha(2B) subtypes was present in total RNA prepared from primary cultures of rat spinal cord neurons. In contrast to spinal cords of postnatal or adult rats that express alpha(2A) and alpha(2C) AR subtypes on different neurons, prenatal spinal cords contain alpha(2A) and alpha(2B) AR subtypes, and these two subtypes appear to be co-expressed in the same cells.
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Affiliation(s)
- Yi Huang
- Department of Physiology, College of Medicine, University of Arizona, Tucson, AZ 85721, USA
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Fujino H, West KA, Regan JW. Phosphorylation of glycogen synthase kinase-3 and stimulation of T-cell factor signaling following activation of EP2 and EP4 prostanoid receptors by prostaglandin E2. J Biol Chem 2002; 277:2614-9. [PMID: 11706038 DOI: 10.1074/jbc.m109440200] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently we have shown that the FP(B) prostanoid receptor, a G-protein-coupled receptor that couples to Galpha(q), activates T-cell factor (Tcf)/lymphoid enhancer factor (Lef)-mediated transcriptional activation (Fujino, H., and Regan, J. W. (2001) J. Biol. Chem. 276, 12489-12492). We now report that the EP(2) and EP(4) prostanoid receptors, which couple to Galpha(s), also activate Tcf/Lef signaling. By using a Tcf/Lef-responsive luciferase reporter gene, transcriptional activity was stimulated approximately 10-fold over basal by 1 h of treatment with prostaglandin E(2) (PGE(2)) in HEK cells that were stably transfected with the human EP(2) and EP(4) receptors. This stimulation of reporter gene activity was accompanied by a PGE(2)-dependent increase in the phosphorylation of both glycogen synthase kinase-3 (GSK-3) and Akt kinase. H-89, an inhibitor of protein kinase A (PKA), completely blocked the agonist-dependent phosphorylation of GSK-3 in both EP(2)- and EP(4)-expressing cells. However, H-89 pretreatment only blocked PGE(2)-stimulated Lef/Tcf reporter gene activity by 20% in EP(4)-expressing cells compared with 65% inhibition in EP(2)-expressing cells. On the other hand wortmannin, an inhibitor of phosphatidylinositol 3-kinase, had the opposite effect and inhibited PGE(2)-stimulated reporter gene activity to a much greater extent in EP(4)-expressing cells as compared with EP(2)-expressing cells. These findings indicate that the activation of Tcf/Lef signaling by EP(2) receptors occurs primarily through a PKA-dependent pathway, whereas EP(4) receptors activate Tcf/Lef signaling mainly through a phosphatidylinositol 3-kinase-dependent pathway. This is the first indication of a fundamental difference in the signaling potential of EP(2) and EP(4) prostanoid receptors.
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MESH Headings
- Androstadienes/pharmacology
- Binding, Competitive
- Blotting, Western
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Differentiation
- Cell Division
- Cell Line
- Cyclic AMP-Dependent Protein Kinases/metabolism
- DNA-Binding Proteins/metabolism
- Dinoprostone/metabolism
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/pharmacology
- Genes, Reporter
- Glycogen Synthase Kinase 3
- Glycogen Synthase Kinases
- Humans
- Isoquinolines/pharmacology
- Luciferases/metabolism
- Lymphoid Enhancer-Binding Factor 1
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphorylation
- Protein Binding
- Radioligand Assay
- Receptors, Prostaglandin E/metabolism
- Receptors, Prostaglandin E, EP2 Subtype
- Receptors, Prostaglandin E, EP4 Subtype
- Signal Transduction
- Sulfonamides
- Time Factors
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
- Wortmannin
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85721-0207, USA
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