51
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Oh JH, Lee JY, Baeg MK, Han KH, Choi MG, Park JM. Antineoplastic Effect of WIN 55,212-2, a Cannabinoid Agonist, in a Murine Xenograft Model of Gastric Cancer. Chemotherapy 2013; 59:200-6. [DOI: 10.1159/000355666] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 09/09/2013] [Indexed: 11/19/2022]
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52
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Kargl J, Balenga N, Parzmair GP, Brown AJ, Heinemann A, Waldhoer M. The cannabinoid receptor CB1 modulates the signaling properties of the lysophosphatidylinositol receptor GPR55. J Biol Chem 2012; 287:44234-48. [PMID: 23161546 PMCID: PMC3531739 DOI: 10.1074/jbc.m112.364109] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 11/15/2012] [Indexed: 11/06/2022] Open
Abstract
The G protein-coupled receptor (GPCR) 55 (GPR55) and the cannabinoid receptor 1 (CB1R) are co-expressed in many tissues, predominantly in the central nervous system. Seven transmembrane spanning (7TM) receptors/GPCRs can form homo- and heteromers and initiate distinct signaling pathways. Recently, several synthetic CB1 receptor inverse agonists/antagonists, such as SR141716A, AM251, and AM281, were reported to activate GPR55. Of these, SR141716A was marketed as a promising anti-obesity drug, but was withdrawn from the market because of severe side effects. Here, we tested whether GPR55 and CB1 receptors are capable of (i) forming heteromers and (ii) whether such heteromers could exhibit novel signaling patterns. We show that GPR55 and CB1 receptors alter each others signaling properties in human embryonic kidney (HEK293) cells. We demonstrate that the co-expression of FLAG-CB1 receptors in cells stably expressing HA-GPR55 specifically inhibits GPR55-mediated transcription factor activation, such as nuclear factor of activated T-cells and serum response element, as well as extracellular signal-regulated kinases (ERK1/2) activation. GPR55 and CB1 receptors can form heteromers, but the internalization of both receptors is not affected. In addition, we observe that the presence of GPR55 enhances CB1R-mediated ERK1/2 and nuclear factor of activated T-cell activation. Our data provide the first evidence that GPR55 can form heteromers with another 7TM/GPCR and that this interaction with the CB1 receptor has functional consequences in vitro. The GPR55-CB1R heteromer may play an important physiological and/or pathophysiological role in tissues endogenously co-expressing both receptors.
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MESH Headings
- Cannabinoids/metabolism
- Dimerization
- Extracellular Signal-Regulated MAP Kinases/genetics
- Extracellular Signal-Regulated MAP Kinases/metabolism
- HEK293 Cells
- Humans
- Lysophospholipids/metabolism
- Protein Binding
- Receptor, Cannabinoid, CB1/chemistry
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptors, Cannabinoid
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction
- Transcriptional Activation
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Affiliation(s)
- Julia Kargl
- From the Institute for Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria
| | - Nariman Balenga
- From the Institute for Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria
- the Molecular Signal Transduction Section, Laboratory of Allergic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-1889
| | - Gerald P. Parzmair
- From the Institute for Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria
| | - Andrew J. Brown
- the Department of Screening and Compound Profiling, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom, and
| | - Akos Heinemann
- From the Institute for Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria
| | - Maria Waldhoer
- From the Institute for Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria
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53
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Schicho R, Storr M. A potential role for GPR55 in gastrointestinal functions. Curr Opin Pharmacol 2012; 12:653-8. [PMID: 23063456 PMCID: PMC3660623 DOI: 10.1016/j.coph.2012.09.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/29/2012] [Accepted: 09/19/2012] [Indexed: 01/06/2023]
Abstract
Despite sharing little homology (10–15%) with cannabinoid-1 (CB1) and cannabinoid-2 (CB2) receptors, the G protein-coupled receptor 55 (GPR55) was initially thought to be a new member of the cannabinoid receptor family. Apart from being activated by various exogenous cannabinoids, GPR55 is also activated by endocannabinoids like anandamide, which is found in organs with high GPR55 expression such as the brain and the gastrointestinal (GI) tract. The phylogenetic distance to the classical CB receptors and its pharmacological responsiveness to certain cannabinoids suggests that GPR55 may constitute a novel class of cannabinoid receptors. GPR55 influences mechanisms in the nervous system, vasculature, kidney and bone. Recent research revealed that GPR55 is also involved in cancer development and inflammatory pain. Because of its presence in the GI tract, several studies have started to focus on the involvement of GPR55 in the physiology and pathophysiology of the gut. The following article intends to discuss the potential role of GPR55 in GI functions.
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Affiliation(s)
- Rudolf Schicho
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
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54
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Kargl J, Haybaeck J, Stančić A, Andersen L, Marsche G, Heinemann A, Schicho R. O-1602, an atypical cannabinoid, inhibits tumor growth in colitis-associated colon cancer through multiple mechanisms. J Mol Med (Berl) 2012; 91:449-58. [PMID: 22965195 DOI: 10.1007/s00109-012-0957-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/06/2012] [Accepted: 08/29/2012] [Indexed: 12/19/2022]
Abstract
Cannabinoids have antiinflammatory and antitumorigenic properties. Some cannabinoids, such as O-1602, have no or only little affinity to classical cannabinoid receptors but exert cannabinoid-like antiinflammatory effects during experimental colitis. Here, we investigated whether O-1602 shows antitumorigenic effects in colon cancer cells and whether it could reduce tumorigenesis in the colon in vivo. The colon cancer cell lines HT-29 and SW480 were used to study the effect of O-1602 on viability and apoptosis. The effect of O-1602 on tumor growth in vivo was studied in a colitis-associated colon cancer mouse model. O-1602 decreased viability and induced apoptosis in colon cancer cells in a concentration-dependent manner (0.1-10 μM). In the mouse model, treatment with O-1602 (3 mg/kg, i.p., 12×) reduced tumor area by 50 % and tumor incidence by 30 %. Histological scoring revealed a significant decrease in tumor load. In tumor tissue, O-1602 decreased levels of proliferating cell nuclear antigen (PCNA), activation of oncogenic transcription factors STAT3 and NFκB p65, and expression of TNF-α while levels for proapoptotic markers, such as p53 and BAX, increased. The in vivo effects of O-1602 on PCNA, BAX, and p53 were also observed in colon cancer cells. The data provide a novel insight into antitumorigenic mechanisms of atypical cannabinoids. O-1602 exerts antitumorigenic effects by targeting colon cancer cells as well as proinflammatory pathways known to promote colitis-associated tumorigenesis. Due to its lack of central sedation, O-1602 could be an interesting compound for the treatment of colon and possibly other cancers.
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Affiliation(s)
- Julia Kargl
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
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55
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Zhao P, Abood ME. GPR55 and GPR35 and their relationship to cannabinoid and lysophospholipid receptors. Life Sci 2012; 92:453-7. [PMID: 22820167 DOI: 10.1016/j.lfs.2012.06.039] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/25/2012] [Accepted: 06/27/2012] [Indexed: 01/23/2023]
Abstract
This review presents a summary of what is known about the G-protein coupled receptors GPR35 and GPR55 and their potential characterization as lysophospholipid or cannabinoid receptors, respectively. Both GPR35 and GPR55 have been implicated as important targets in pain and cancer, and additional diseases as well. While kynurenic acid was suggested to be an endogenous ligand for GPR35, so was 2-arachidonoyl lysophosphatidic acid (LPA). Similarly, GPR55 has been suggested to be a cannabinoid receptor, but is quite clearly also a receptor for lysophosphatidylinositol. Interestingly, 2-arachidonyl glycerol (2-AG), an endogenous ligand for cannabinoid receptors, can be metabolized to 2-arachidonoyl LPA through the action of a monoacylglycerol kinase; the reverse reaction has also been demonstrated. Thus, it appears that mutual interconversion is possible between 2-arachidonoyl LPA and 2-AG within a cell, though the direction of the reaction may be site-dependent. The GPR55 natural ligand, 2-arachidonoyl LPI, can be degraded either to 2-AG by phospholipase C or to 2-arachidonoyl LPA by phospholipase D. Thus, GPR35, GPR55 and CB receptors are linked together through their natural ligand conversions. Additional agonists and antagonists have been identified for both GPR35 and GPR55, which will facilitate the future study of these receptors with respect to their physiological function. Potential therapeutic targets include pain, cancer, metabolic diseases and drug addiction.
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MESH Headings
- Animals
- Cannabinoids/pharmacology
- Cannabinoids/therapeutic use
- Gene Expression
- Humans
- Ligands
- Receptors, Cannabinoid/drug effects
- Receptors, Cannabinoid/genetics
- Receptors, Cannabinoid/physiology
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Receptors, Lysophospholipid/drug effects
- Receptors, Lysophospholipid/genetics
- Receptors, Lysophospholipid/physiology
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Affiliation(s)
- Pingwei Zhao
- Center for Substance Abuse Research and Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA, USA
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56
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The orphan receptor GPR55 drives skin carcinogenesis and is upregulated in human squamous cell carcinomas. Oncogene 2012; 32:2534-42. [PMID: 22751111 DOI: 10.1038/onc.2012.278] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
G protein-coupled receptors (GPCRs) control crucial physiological processes and their dysfunction contributes to various human diseases, including cancer. The orphan GPCR GPR55 was identified and cloned more than a decade ago, but very little is known about its physio-pathological relevance. It has been recently shown that GPR55 controls the behavior of human cancer cell lines in culture and xenografts. However, the assessment of the actual role of this receptor in malignant transformation in vivo is hampered by the lack of studies on its functional impact in clinically-relevant models of cancer. Here we demonstrate that GPR55 drives mouse skin tumor development. Thus, GPR55-deficient mice were more resistant to DMBA/TPA-induced papilloma and carcinoma formation than their wild-type littermates. GPR55 exerted this pro-tumor effect primarily by conferring a proliferative advantage on cancer cells. In addition, GPR55 enhanced skin cancer cell anchorage-independent growth, invasiveness and tumorigenicity in vivo, suggesting that it promotes not only tumor development but also tumor aggressiveness. Finally, we observed that GPR55 is upregulated in human skin tumors and other human squamous cell carcinomas compared with the corresponding healthy tissues. Altogether, these findings reveal the pivotal importance of GPR55 in skin tumor development, and suggest that this receptor may be used as a new biomarker and therapeutic target in squamous cell carcinomas.
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57
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Sharir H, Console-Bram L, Mundy C, Popoff SN, Kapur A, Abood ME. The endocannabinoids anandamide and virodhamine modulate the activity of the candidate cannabinoid receptor GPR55. J Neuroimmune Pharmacol 2012; 7:856-65. [PMID: 22454039 DOI: 10.1007/s11481-012-9351-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 02/21/2012] [Indexed: 01/28/2023]
Abstract
The role of cannabinoid receptors in inflammation has been the topic of many research endeavors. Despite this effort, to date the involvement of the endocannabinoid system (ECS) in inflammation remains obscure. The ambiguity of cannabinoid involvement may be explained by the existence of cannabinoid receptors, other than CB(1) and CB(2), or a consequence of interaction of endocannabinoids with other signaling systems. GPR55 has been proposed to be a cannabinoid receptor; however the interaction of the endocannabinoid system with GPR55 remains elusive. Consequently this study set about to examine the effects of the endocannabinoids, anandamide (AEA) and virodhamine, on GPR55 mediated signaling. Specifically, we assessed changes in β-arrestin2 (βarr2) distribution and GPR55 receptor internalization following activation by lysophosphatidylinositol (LPI), the synthetic cannabinoid ligand SR141716A, and new selective synthetic GPR55 agonists. Data obtained from the experiments presented herein demonstrate that AEA and virodhamine modulate agonist-mediated recruitment of βarr2. AEA and virodhamine act as partial agonists; enhancing the agonist effect at low concentrations and inhibiting it at high concentrations. Furthermore, both virodhamine and AEA significantly attenuated agonist-induced internalization of GPR55. These effects are attributed to the expression of GPR55, and not CB(1) and CB(2) receptors, as we have established negligible expression of CB(1) and CB(2) in these GPR55-transfected U2OS cells. The identification of select endocannabinoids as GPR55 modulators will aide in elucidating the function of GPR55 in the ECS.
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Affiliation(s)
- Haleli Sharir
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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58
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Henstridge CM. Off-target cannabinoid effects mediated by GPR55. Pharmacology 2012; 89:179-87. [PMID: 22433274 DOI: 10.1159/000336872] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 01/18/2012] [Indexed: 12/14/2022]
Abstract
Given the vast therapeutic potential of the endocannabinoid system, the revelation of a novel cannabinoid-sensitive target was treated with great excitement. The orphan G-protein coupled receptor 55 (GPR55) was initially touted as a novel cannabinoid target in early industrial patent literature. Consequently, numerous studies have revealed GPR55 expression in a diverse array of cells and tissues, regulating various physiological and pathological processes. Although a confusing cannabinoid profile has prevented its classification as a cannabinoid receptor, the therapeutic potential of the receptor cannot be denied, with roles in cancer progression, bone resorption and analgesia. This commentary aims to summarize GPR55 expression data and speculate on potential therapeutic exploitation of this enigmatic orphan receptor.
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59
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Villa-Morales M, Fernández-Piqueras J. Targeting the Fas/FasL signaling pathway in cancer therapy. Expert Opin Ther Targets 2012; 16:85-101. [PMID: 22239437 DOI: 10.1517/14728222.2011.628937] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION The Fas/FasL system plays a significant role in tumorigenesis. Research has shown that its impairment in cancer cells may lead to apoptosis resistance and contribute to tumor progression. Thus, the development of effective therapies targeting the Fas/FasL system may play an important role in the fight against cancer. AREAS COVERED In this review the recent literature on targeting the Fas/FasL system for therapeutic exploitation at different levels is reviewed. Promising pre-clinical approaches and various exceptions are highlighted. The potential of combined therapies is also explored, whereby tumor sensitivity to Fas-mediated apoptosis is restored, before an effective targeted therapy is employed. EXPERT OPINION The success of the Fas/FasL system targeting for therapeutics will require a better understanding of the alterations conferring resistance, in order to use the most appropriate sensitizing chemotherapeutic or radiotherapeutic agents in combination with effective targeted therapies.
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Affiliation(s)
- María Villa-Morales
- Department of Biology, Universidad Autónoma de Madrid, CIBER de Enfermedades Raras, Madrid, Spain
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60
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Henstridge CM, Balenga NAB, Kargl J, Andradas C, Brown AJ, Irving A, Sanchez C, Waldhoer M. Minireview: recent developments in the physiology and pathology of the lysophosphatidylinositol-sensitive receptor GPR55. Mol Endocrinol 2011; 25:1835-48. [PMID: 21964594 PMCID: PMC5417173 DOI: 10.1210/me.2011-1197] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 09/01/2011] [Indexed: 11/19/2022] Open
Abstract
Emerging data suggest that off-target cannabinoid effects may be mediated via novel seven-transmembrane spanning/G protein-coupled receptors. Due to its cannabinoid sensitivity, the G protein-coupled receptor 55 (GPR55) was recently proposed as a candidate; however, GPR55 is phylogenetically distinct from the traditional cannabinoid receptors, and the conflicting pharmacology, signaling, and functional data have prevented its classification as a novel cannabinoid receptor. Indeed, the most consistent and potent agonist to date is the noncannabinoid lysophospholipid, lysophosphatidylinositol. Here we present new human GPR55 mRNA expression data, providing supportive evidence of GPR55 expression in a vast array of tissues and cell types. Moreover, we summarize major recent developments in GPR55 research and aim to update the reader in the rapidly expanding fields of GPR55 pharmacology, physiology, and pathology.
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