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Non-Canonical Cannabinoid Receptors with Distinct Binding and Signaling Properties in Prostate and Other Cancer Cell Types Mediate Cell Death. Int J Mol Sci 2022; 23:ijms23063049. [PMID: 35328467 PMCID: PMC8954350 DOI: 10.3390/ijms23063049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 02/01/2023] Open
Abstract
Cannabinoids exert anti-cancer actions; however, the underlying cytotoxic mechanisms and the cannabinoid receptors (CBRs) involved remain unclear. In this study, CBRs were characterized in several cancer cell lines. Radioligand binding screens surprisingly revealed specific binding only for the non-selective cannabinoid [3H]WIN-55,212-2, and not [3H]CP-55,940, indicating that the expressed CBRs exhibit atypical binding properties. Furthermore, [3H]WIN-55,212-2 bound to a single site in all cancer cells with high affinity and varying densities. CBR characteristics were next compared between human prostate cancer cell lines expressing low (PC-3) and high (DU-145) CBR density. Although mRNA for canonical CBRs was detected in both cell lines, only 5 out of 15 compounds with known high affinity for canonical CBRs displaced [3H]WIN-55,212-2 binding. Functional assays further established that CBRs in prostate cancer cells exhibit distinct signaling properties relative to canonical Gi/Go-coupled CBRs. Prostate cancer cells chronically exposed to both CBR agonists and antagonists/inverse agonists produced receptor downregulation, inconsistent with actions at canonical CBRs. Treatment of DU-145 cells with CBR ligands increased LDH-release, decreased ATP-dependent cell viability, and produced mitochondrial membrane potential depolarization. In summary, several cancer cell lines express CBRs with binding and signaling profiles dissimilar to canonical CBRs. Drugs selectively targeting these atypical CBRs might exhibit improved anti-cancer properties.
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Shoeib AM, Yarbrough AL, Ford BM, Franks LN, Urbaniak A, Hensley LL, Benson LN, Mu S, Radominska-Pandya A, Prather PL. Characterization of cannabinoid receptors expressed in Ewing sarcoma TC-71 and A-673 cells as potential targets for anti-cancer drug development. Life Sci 2021; 285:119993. [PMID: 34592231 PMCID: PMC10395316 DOI: 10.1016/j.lfs.2021.119993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/10/2021] [Accepted: 09/19/2021] [Indexed: 10/20/2022]
Abstract
AIMS Characterizing cannabinoid receptors (CBRs) expressed in Ewing sarcoma (EWS) cell lines as potential targets for anti-cancer drug development. MAIN METHODS CBR affinity and function were examined by competitive binding and G-protein activation, respectively. Cannabinoid-mediated cytotoxicity and cell viability were evaluated by LDH, and trypan blue assays, respectively. KEY FINDINGS qRT-PCR detected CB1 (CB1R) and CB2 receptor (CB2R) mRNA in TC-71 cells. However, binding screens revealed that CBRs expressed exhibit atypical properties relative to canonical receptors, because specific binding in TC-71 could only be demonstrated by the established non-selective CB1/CB2R radioligand [3H]WIN-55,212-2, but not CB1/CB2R radioligand [3H]CP-55,940. Homologous receptor binding demonstrated that [3H]WIN-55,212-2 binds to a single site with nanomolar affinity, expressed at high density. Further support for non-canonical CBRs expression is provided by subsequent binding screens, revealing that only 9 out of 28 well-characterized cannabinoids with high affinity for canonical CB1 and/or CB2Rs were able to displace [3H]WIN-55,212-2, whereas two ligands enhanced [3H]WIN-55,212-2 binding. Five cannabinoids producing the greatest [3H]WIN-55,212-2 displacement exhibited high nanomolar affinity (Ki) for expressed receptors. G-protein modulation and adenylyl cyclase assays further indicate that these CBRs exhibit distinct signaling/functional profiles compared to canonical CBRs. Importantly, cannabinoids with the highest affinity for non-canonical CBRs reduced TC-71 viability and induced cytotoxicity in a time-dependent manner. Studies in a second EWS cell line (A-673) showed similar atypical binding properties of expressed CBRs, and cannabinoid treatment produced cytotoxicity. SIGNIFICANCE Cannabinoids induce cytotoxicity in EWS cell lines via non-canonical CBRs, which might be a potential therapeutic target to treat EWS.
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Affiliation(s)
- Amal M Shoeib
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Azure L Yarbrough
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Benjamin M Ford
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lirit N Franks
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Alicja Urbaniak
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lori L Hensley
- Department of Biology, Jacksonville State University, Jacksonville, AL, United States of America
| | - Lance N Benson
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Shengyu Mu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Paul L Prather
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America.
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Penthala NR, Shoeib A, Dachavaram SS, Cabanlong CV, Yang J, Zhan CG, Prather PL, Crooks PA. 7-Azaindolequinuclidinones (7-AIQD): A novel class of cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptor ligands. Bioorg Med Chem Lett 2020; 30:127501. [PMID: 32882418 DOI: 10.1016/j.bmcl.2020.127501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 08/12/2020] [Accepted: 08/16/2020] [Indexed: 11/29/2022]
Abstract
A series of N-benzyl-7-azaindolequinuclidinone (7-AIQD) analogs have been synthesized and evaluated for affinity toward CB1 and CB2 cannabinoid receptors and identified as a novel class of cannabinoid receptor ligands. Structure-activity relationship (SAR) studies indicate that 7-AIQD analogs are dual CB1/CB2 receptor ligands exhibiting high potency with somewhat greater selectivity towards CB2 receptors compared to the previously reported indolequinuclidinone (IQD) analogs. Initial binding assays showed that 7-AIQD analogs 8b, 8d, 8f, 8g and 9b (1 μM) produced more that 50% displacement of the CB1/CB2 non-selective agonist CP-55,940 (0.1 nM). Furthermore, Ki values determined from full competition binding curves showed that analogs 8a, 8b and 8g exhibit high affinity (110, 115 and 23.7 nM, respectively) and moderate selectivity (26.3, 6.1 and 9.2-fold, respectively) for CB2 relative to CB1 receptors. Functional studies examining modulation of G-protein activity demonstrated that 8a acts as a neutral antagonist at CB1 and CB2 receptors, while 8b exhibits inverse agonist activity at these receptors. Analogs 8f and 8g exhibit different intrinsic activities, depending on the receptor examined. Molecular docking and binding free energy calculations for the most active compounds (8a, 8b, 8f, and 8g) were performed to better understand the CB2 receptor-selective mechanism at the atomic level. Compound 8g exhibited the highest predicted binding affinity at both CB1 and CB2 receptors, and all four compounds were shown to have higher predicted binding affinities with the CB2 receptor compared to their corresponding binding affinities with the CB1 receptor. Further structural optimization of 7-AIQD analogs may lead to the identification of potential clinical agents.
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Affiliation(s)
- Narsimha Reddy Penthala
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Amal Shoeib
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Soma Shekar Dachavaram
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Christian V Cabanlong
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Jingfang Yang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
| | - Paul L Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Peter A Crooks
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Ye L, Cao Z, Wang W, Zhou N. New Insights in Cannabinoid Receptor Structure and Signaling. Curr Mol Pharmacol 2020; 12:239-248. [PMID: 30767756 DOI: 10.2174/1874467212666190215112036] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/26/2022]
Abstract
BACKGROUND Cannabinoid has long been used for medicinal purposes. Cannabinoid signaling has been considered the therapeutic target for treating pain, addiction, obesity, inflammation, and other diseases. Recent studies have suggested that in addition to CB1 and CB2, there are non-CB1 and non-CB2 cannabinoid-related orphan GPCRs including GPR18, GPR55, and GPR119. In addition, CB1 and CB2 display allosteric binding and biased signaling, revealing correlations between biased signaling and functional outcomes. Interestingly, new investigations have indicated that CB1 is functionally present within the mitochondria of striated and heart muscles directly regulating intramitochondrial signaling and respiration. CONCLUSION In this review, we summarize the recent progress in cannabinoid-related orphan GPCRs, CB1/CB2 structure, Gi/Gs coupling, allosteric ligands and biased signaling, and mitochondria-localized CB1, and discuss the future promise of this research.
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Affiliation(s)
- Lingyan Ye
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, China
| | - Zheng Cao
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, China
| | - Weiwei Wang
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, China
| | - Naiming Zhou
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, China
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Al-Zoubi R, Morales P, Reggio PH. Structural Insights into CB1 Receptor Biased Signaling. Int J Mol Sci 2019; 20:E1837. [PMID: 31013934 PMCID: PMC6515405 DOI: 10.3390/ijms20081837] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/21/2022] Open
Abstract
The endocannabinoid system has emerged as a promising target for the treatment of numerous diseases, including cancer, neurodegenerative disorders, and metabolic syndromes. Thus far, two cannabinoid receptors, CB1 and CB2, have been discovered, which are found predominantly in the central nervous system (CB1) or the immune system (CB2), among other organs and tissues. CB1 receptor ligands have been shown to induce a complex pattern of intracellular effects. The binding of a ligand induces distinct conformational changes in the receptor, which will eventually translate into distinct intracellular signaling pathways through coupling to specific intracellular effector proteins. These proteins can mediate receptor desensitization, trafficking, or signaling. Ligand specificity and selectivity, complex cellular components, and the concomitant expression of other proteins (which either regulate the CB1 receptor or are regulated by the CB1 receptor) will affect the therapeutic outcome of its targeting. With an increased interest in G protein-coupled receptors (GPCR) research, in-depth studies using mutations, biological assays, and spectroscopic techniques (such as NMR, EPR, MS, FRET, and X-ray crystallography), as well as computational modelling, have begun to reveal a set of concerted structural features in Class A GPCRs which relate to signaling pathways and the mechanisms of ligand-induced activation, deactivation, or activity modulation. This review will focus on the structural features of the CB1 receptor, mutations known to bias its signaling, and reported studies of CB1 receptor ligands to control its specific signaling.
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Affiliation(s)
- Rufaida Al-Zoubi
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science & Technology, P.O.BOX 3030, Irbid 22110, Jordan.
| | - Paula Morales
- Departamento de Química-Física Biológica, Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
| | - Patricia H Reggio
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, NC 27412, USA.
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Ford BM, Cabanlong CV, Tai S, Franks LN, Penthala NR, Crooks PA, Prather PL, Fantegrossi WE. Reduced Tolerance and Asymmetrical Crosstolerance to Effects of the Indole Quinuclidinone Analog PNR-4-20, a G Protein-Biased Cannabinoid 1 Receptor Agonist in Mice: Comparisons with Δ 9-Tetrahydrocannabinol and JWH-018. J Pharmacol Exp Ther 2019; 369:259-269. [PMID: 30833484 DOI: 10.1124/jpet.118.252965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 02/11/2019] [Indexed: 01/01/2023] Open
Abstract
Most cannabinoid 1 receptor (CB1R) agonists will signal through both G protein-dependent and -independent pathways in an unbiased manner. Recruitment of β-arrestin 2 desensitizes and internalizes receptors, producing tolerance that limits therapeutic utility of cannabinoids for chronic conditions. We developed the indole quinuclidinone (IQD) analog (Z)-2-((1-(4-fluorobenzyl)-1H-indol-3-yl)methylene)quinuclidin-3-one (PNR-4-20) as a novel G protein-biased agonist at CB1Rs, and the present studies determine if repeated administration of PNR-4-20 produces lesser tolerance to in vivo effects compared with unbiased CB1R agonists Δ9-tetrahydrocannabinol (Δ9-THC) and 1-pentyl-3-(1-naphthoyl)indole (JWH-018). Adult male National Institutes of Health Swiss mice were administered comparable doses of PNR-4-20 (100 mg/kg), Δ9-THC (30 mg/kg), or JWH-018 (3 mg/kg) once per day for five consecutive days to determine tolerance development to hypothermic, antinociceptive, and cataleptic effects. Persistence of tolerance was then determined after a drug abstinence period. We found that unbiased CB1R agonists Δ9-THC and JWH-018 produced similar tolerance to these effects, but lesser tolerance was observed with PNR-4-20 for hypothermic and cataleptic effects. Tolerance to the effects of PNR-4-20 completely recovered after drug abstinence, while residual tolerance was always observed with unbiased CB1R agonists. Repeated treatment with PNR-4-20 and Δ9-THC produced asymmetric crosstolerance to hypothermic effects. Importantly, binding studies suggest PNR-4-20 produced significantly less downregulation of CB1Rs relative to Δ9-THC in hypothalamus and thalamus of chronically treated mice. These studies suggest that the G protein-biased CB1R agonist PNR-4-20 produces significantly less tolerance than unbiased cannabinoid agonists, and that the IQD analogs should be investigated further as a novel molecular scaffold for development of new therapeutics.
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Affiliation(s)
- Benjamin M Ford
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Christian V Cabanlong
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Sherrica Tai
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Lirit N Franks
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Narsimha R Penthala
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Peter A Crooks
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Paul L Prather
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine (B.M.F., C.V.C., S.T., L.N.F., P.L.P., W.E.F.), and Department of Pharmaceutical Sciences, College of Pharmacy (N.R.P., P.A.C.), University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Khurana L, Mackie K, Piomelli D, Kendall DA. Modulation of CB1 cannabinoid receptor by allosteric ligands: Pharmacology and therapeutic opportunities. Neuropharmacology 2017; 124:3-12. [PMID: 28527758 PMCID: PMC5540789 DOI: 10.1016/j.neuropharm.2017.05.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/12/2017] [Accepted: 05/16/2017] [Indexed: 02/03/2023]
Abstract
Cannabinoid pharmacology has been intensely studied because of cannabis' pervasive medicinal and non-medicinal uses as well as for the therapeutic potential of cannabinoid-based drugs for the treatment of pain, anxiety, substance abuse, obesity, cancer and neurodegenerative disorders. The identification of allosteric modulators of the cannabinoid receptor 1 (CB1) has given a new direction to the development of cannabinoid-based therapeutics due to the many advantages offered by targeting allosteric site(s). Allosteric receptor modulators hold potential to develop subtype-specific and pathway-specific therapeutics. Here we briefly discuss the first-generation of allosteric modulators of CB1 receptor, their structure-activity relationships, signaling pathways and the allosteric binding site(s) on the CB1 receptor. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Affiliation(s)
- Leepakshi Khurana
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States
| | - Ken Mackie
- Gill Center and Departmental of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, United States
| | - Daniele Piomelli
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, United States; Department of Biological Chemistry, University of California, Irvine, CA 92697, United States
| | - Debra A Kendall
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States.
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Ford BM, Franks LN, Tai S, Fantegrossi WE, Stahl EL, Berquist MD, Cabanlong CV, Wilson CD, Penthala NR, Crooks PA, Prather PL. Characterization of structurally novel G protein biased CB 1 agonists: Implications for drug development. Pharmacol Res 2017; 125:161-177. [PMID: 28838808 DOI: 10.1016/j.phrs.2017.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 08/11/2017] [Accepted: 08/12/2017] [Indexed: 01/08/2023]
Abstract
The human cannabinoid subtype 1 receptor (hCB1R) is highly expressed in the CNS and serves as a therapeutic target for endogenous ligands as well as plant-derived and synthetic cannabinoids. Unfortunately, acute use of hCB1R agonists produces unwanted psychotropic effects and chronic administration results in development of tolerance and dependence, limiting the potential clinical use of these ligands. Studies in β-arrestin knockout mice suggest that interaction of certain GPCRs, including μ-, δ-, κ-opioid and hCB1Rs, with β-arrestins might be responsible for several adverse effects produced by agonists acting at these receptors. Indeed, agonists that bias opioid receptor activation toward G-protein, relative to β-arrestin signaling, produce less severe adverse effects. These observations indicate that therapeutic utility of agonists acting at hCB1Rs might be improved by development of G-protein biased hCB1R agonists. Our laboratory recently reported a novel class of indole quinulidinone (IQD) compounds that bind cannabinoid receptors with relatively high affinity and act with varying efficacy. The purpose of this study was to determine whether agonists in this novel cannabinoid class exhibit ligand bias at hCB1 receptors. Our studies found that a novel IQD-derived hCB1 receptor agonist PNR-4-20 elicits robust G protein-dependent signaling, with transduction ratios similar to the non-biased hCB1R agonist CP-55,940. In marked contrast to CP-55,940, PNR-4-20 produces little to no β-arrestin 2 recruitment. Quantitative calculation of bias factors indicates that PNR-4-20 exhibits from 5.4-fold to 29.5-fold bias for G protein, relative to β-arrestin 2 signaling (when compared to G protein activation or inhibition of forskolin-stimulated cAMP accumulation, respectively). Importantly, as expected due to reduced β-arrestin 2 recruitment, chronic exposure of cells to PNR-4-20 results in significantly less desensitization and down-regulation of hCB1Rs compared to similar treatment with CP-55,940. PNR-4-20 (i.p.) is active in the cannabinoid tetrad in mice and chronic treatment results in development of less persistent tolerance and no significant withdrawal signs when compared to animals repeatedly exposed to the non-biased full agoinst JWH-018 or Δ9-THC. Finally, studies of a structurally similar analog PNR- 4-02 show that it is also a G protein biased hCB1R agonist. It is predicted that cannabinoid agonists that bias hCB1R activation toward G protein, relative to β-arrestin 2 signaling, will produce fewer and less severe adverse effects both acutely and chronically.
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Affiliation(s)
- Benjamin M Ford
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Lirit N Franks
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Sherrica Tai
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Edward L Stahl
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA.
| | - Michael D Berquist
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Christian V Cabanlong
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Catheryn D Wilson
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Narsimha R Penthala
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Peter A Crooks
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Paul L Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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9
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Seltzman HH, Maitra R, Bortoff K, Henson J, Reggio PH, Wesley D, Tam J. Metabolic Profiling of CB1 Neutral Antagonists. Methods Enzymol 2017; 593:199-215. [PMID: 28750803 DOI: 10.1016/bs.mie.2017.06.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PIMSR is among the first neutral antagonists for the CB1R and was demonstrated pharmacologically to bind to the CB1R, yet not alter calcium flux. It was further shown computationally to be able to stabilize both the active and inactive states of CB1R revealing the molecular interactions that mechanistically afford the property of neutral antagonism. PIMSR shows dramatic positive effects in reducing weight, food intake, and adiposity as well as in improving glycemic control and lipid homeostasis in high-fat diet-induced obese mice, but also shows increased ALT and liver weight as markers of liver injury with chronic administration. Further, in a separate study, 3-day administration of PIMSR in C57BL/6J mice, hepatic steatosis from an acute administration of high of ethanol was significantly reduced. Also, it partially prevented alcohol-induced increases in ALT, AST, and LDH. The differences in ALT levels in obese and nonobese mice under different test paradigms are unlikely to be due to neutral antagonism itself since other neutral antagonists (AM6545) do not exhibit liver injury. The brain levels of low micromolar would support significant brain CB1 receptor occupancy (re: Ki=17nM), thus potentially including both CNS and peripheral influences on the observed weight loss. Overall, these studies suggest that marked improvements in aspects of metabolic disease and alcoholic steatosis can be realized with CB1R neutral antagonists and hence warrants the exploration of further members of this class of cannabinoid ligands.
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Affiliation(s)
- Herbert H Seltzman
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, United States.
| | - Rangan Maitra
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, United States
| | | | | | - Patricia H Reggio
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Daniel Wesley
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, United States
| | - Joseph Tam
- Obesity and Metabolism Laboratory, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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Franks LN, Ford BM, Prather PL. Selective Estrogen Receptor Modulators: Cannabinoid Receptor Inverse Agonists with Differential CB1 and CB2 Selectivity. Front Pharmacol 2016; 7:503. [PMID: 28066250 PMCID: PMC5177629 DOI: 10.3389/fphar.2016.00503] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/07/2016] [Indexed: 12/16/2022] Open
Abstract
Selective estrogen receptor modulators (SERMs) are used to treat estrogen receptor (ER)-positive breast cancer and osteoporosis. Interestingly, tamoxifen and newer classes of SERMs also exhibit cytotoxic effects in cancers devoid of ERs, indicating a non-estrogenic mechanism of action. Indicative of a potential ER-independent target, reports demonstrate that tamoxifen binds to cannabinoid receptors (CBRs) with affinity in the low μM range and acts as an inverse agonist. To identify cannabinoids with improved pharmacological properties relative to tamoxifen, and further investigate the use of different SERM scaffolds for future cannabinoid drug development, this study characterized the affinity and activity of SERMs in newer structural classes at CBRs. Fourteen SERMs from five structurally distinct classes were screened for binding to human CBRs. Compounds from four of five SERM classes examined bound to CBRs. Subsequent studies fully characterized CBR affinity and activity of one compound from each class. Ospemifine (a triphenylethylene) selectively bound to CB1Rs, while bazedoxifine (an indole) bound to CB2Rs with highest affinity. Nafoxidine (a tetrahydronaphthalene) and raloxifene (RAL; a benzothiaphene) bound to CB1 and CB2Rs non-selectively. All four compounds acted as inverse agonists at CB1 and CB2Rs, reducing basal G-protein activity with IC50 values in the nM to low μM range. Ospemifine, bazedoxifene and RAL also acted as inverse agonists to elevate basal intracellular cAMP levels in intact CHO-hCB2 cells. The four SERMs examined also acted as CB1 and CB2R antagonists in the cAMP assay, producing rightward shifts in the concentration-effect curve of the CBR agonist CP-55,940. In conclusion, newer classes of SERMs exhibit improved pharmacological characteristics (e.g., in CBR affinity and selectivity) relative to initial studies with tamoxifen, and thus suggest that different SERM scaffolds may be useful for development of safe and selective drugs acting via CBRs.
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Affiliation(s)
- Lirit N Franks
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock AR, USA
| | - Benjamin M Ford
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock AR, USA
| | - Paul L Prather
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock AR, USA
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Ford BM, Franks LN, Radominska-Pandya A, Prather PL. Tamoxifen Isomers and Metabolites Exhibit Distinct Affinity and Activity at Cannabinoid Receptors: Potential Scaffold for Drug Development. PLoS One 2016; 11:e0167240. [PMID: 27936172 PMCID: PMC5147891 DOI: 10.1371/journal.pone.0167240] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/10/2016] [Indexed: 01/29/2023] Open
Abstract
Tamoxifen (Tam) is a selective estrogen receptor (ER) modulator (SERM) that is an essential drug to treat ER-positive breast cancer. Aside from known actions at ERs, recent studies have suggested that some SERMs like Tam also exhibit novel activity at cannabinoid subtype 1 and 2 receptors (CB1R and CB2Rs). Interestingly, cis- (E-Tam) and trans- (Z-Tam) isomers of Tam exhibit over a 100-fold difference in affinity for ERs. Therefore, the current study assessed individual isomers of Tam and subsequent cytochrome P450 metabolic products, 4-hydroxytamoxifen (4OHT) and 4-hydroxy-N-desmethyl tamoxifen (End) for affinity and activity at CBRs. Results showed that Z-4OHT, but not Z-Tam or Z-End, exhibits higher affinity for both CB1 and CB2Rs relative to the E-isomer. Furthermore, Z- and E-isomers of Tam and 4OHT show slightly higher affinity for CB2Rs, while both End isomers are relatively CB1R-selective. When functional activity was assessed by G-protein activation and regulation of the downstream effector adenylyl cyclase, all isomers examined act as full CB1 and CB2R inverse agonists. Interestingly, Z-Tam appears to be more efficacious than the full inverse agonist AM630 at CB2Rs, while both Z-Tam and Z-End exhibit characteristics of insurmountable antagonism at CB1 and CB2Rs, respectively. Collectively, these results suggest that the SERMs Tam, 4OHT and End elicit ER-independent actions via CBRs in an isomer-specific manner. As such, this novel structural scaffold might be used to develop therapeutically useful drugs for treatment of a variety of diseases mediated via CBRs.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Binding, Competitive
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- CHO Cells
- Cannabinoid Receptor Agonists/metabolism
- Cannabinoid Receptor Agonists/pharmacology
- Cannabinoid Receptor Antagonists/metabolism
- Cannabinoid Receptor Antagonists/pharmacology
- Colforsin/metabolism
- Colforsin/pharmacology
- Cricetinae
- Cricetulus
- Cyclic AMP/metabolism
- Cyclohexanols/metabolism
- Cyclohexanols/pharmacology
- Female
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Indoles/metabolism
- Indoles/pharmacology
- Isomerism
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/metabolism
- Selective Estrogen Receptor Modulators/chemistry
- Selective Estrogen Receptor Modulators/metabolism
- Selective Estrogen Receptor Modulators/pharmacology
- Tamoxifen/analogs & derivatives
- Tamoxifen/chemistry
- Tamoxifen/metabolism
- Tamoxifen/pharmacology
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Affiliation(s)
- Benjamin M. Ford
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lirit N. Franks
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Paul L. Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
- * E-mail:
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