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Virtual screening of novel CB2 ligands using a comparative model of the human cannabinoid CB2 receptor.

To identify novel selective CB2 lead compounds, a comparative model of the CB2 receptor was constructed using the high-resolution bovine rhodopsin X-ray structure as a template. The CB2 model was utilized both in building the database queries and in filtering the hit compounds by a docking and scoring method. In G-protein activation assays, 1-isoquinolyl[3-(trifluoromethyl)phenyl]methanone (40, NRB 04079) was found to act as a selective agonist at the human CB2 receptor.

Animals↗

Echinacea alkylamides modulate TNF-alpha gene expression via cannabinoid receptor CB2 and multiple signal transduction pathways.

Echinacea plant preparations are widely used in the prevention and treatment of common cold. However, so far no molecular mechanism of action has been proposed. We analyzed the standardized tincture Echinaforce and found that it induced de novo synthesis of tumor necrosis factor alpha (TNF-alpha) mRNA in primary human monocytes/macrophages, but not TNF-alpha protein. Moreover, LPS-stimulated TNF-alpha protein was potently inhibited in the early phase but prolonged in the late phase. A study of the main constituents of the extract showed that the alkylamides dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides (1/2), trienoic (3) and dienoic acid (4) derivatives are responsible for this effect. The upregulation of TNF-alpha mRNA was found to be mediated by CB2 receptors, increased cAMP, p38/MAPK and JNK signaling, as well as NF-kappaB and ATF-2/CREB-1 activation. This study is the first to report a possible molecular mechanism of action of Echinacea, highlighting the role of alkylamides as potent immunomodulators and potential ligands for CB2 receptors.

Cells, Cultured↗

In vitro pharmacological characterization of AM1241: a protean agonist at the cannabinoid CB2 receptor?

BACKGROUND AND PURPOSE: The CB2 receptor has been proposed as a novel target for the treatment of pain, and CB2 receptor agonists defined in in vitro assays have demonstrated analgesic activity in animal models. Based on its in vivo analgesic efficacy, AM1241 has been classified as a CB2-selective agonist. However, in vitro characterization of AM1241 in functional assays has not been reported. EXPERIMENTAL APPROACH: In this study, AM1241 was characterized across multiple in vitro assays employing heterologous recombinant receptor expression systems to assess its binding potencies at the human CB2 and CB1 receptors and its functional efficacies at the human CB2 receptor. KEY RESULTS: AM1241 exhibited distinct functional properties depending on the assay conditions employed, a unique profile in contrast to those of the agonist CP 55,940 and the inverse agonist SR144528. AM1241 displayed neutral antagonist activities in FLIPR and cyclase assays. However, when cyclase assays were performed using lower forskolin concentrations for stimulation, AM1241 exhibited partial agonist efficacy. In addition, it behaved as a partial agonist in ERK (or MAP) kinase assays. CONCLUSIONS AND IMPLICATIONS: The unusual phenomenon of inconsistent functional efficacies suggests that AM1241 is a protean agonist at the CB2 receptor. We postulate that functional efficacies displayed by protean agonists in various assay systems may depend on the levels of receptor constitutive activities exhibited in the assay systems, and therefore, efficacies observed in in vitro assays may not predict in vivo activities.

Cannabinoids↗

Identification and functional characterization of brainstem cannabinoid CB2 receptors.

The presence and function of CB2 receptors in central nervous system (CNS) neurons are controversial. We report the expression of CB2 receptor messenger RNA and protein localization on brainstem neurons. These functional CB2 receptors in the brainstem were activated by a CB2 receptor agonist, 2-arachidonoylglycerol, and by elevated endogenous levels of endocannabinoids, which also act at CB1 receptors. CB2 receptors represent an alternative site of action of endocannabinoids that opens the possibility of nonpsychotropic therapeutic interventions using enhanced endocannabinoid levels in localized brain areas.

Animals↗

Novel 4-oxo-1,4-dihydroquinoline-3-carboxamide derivatives as new CB2 cannabinoid receptors agonists: synthesis, pharmacological properties and molecular modeling.

Recent data indicated that the CB(2) cannabinoid receptor constitutes an attractive drug target due to its potential functional role in several physiological and pathological processes. A set of 4-oxo-1,4-dihydroquinoline-3-carboxamide derivatives, characterized by the presence of some important structural requirements exhibited by other classes of cannabinoid ligands, such as an aliphatic or aromatic carboxamide group in position 3, and an alkyl or benzyl group in position 1, was synthesized and assayed to measure their respective affinity for both human CB(1) and CB(2) cannabinoid receptors. The results indicate that these 3-carboxamido-quinolones derivatives exhibited a CB(2) receptor selectivity, particularly derivatives 28-30, and 32R. Moreover, in the [(35)S]-GTPgammaS binding assay, all the compounds behaved as CB(2) receptor agonists. Molecular modeling studies showed that compound 30 interacts with the CB(2) receptor through a combination of hydrogen bond and aromatic/hydrophobic interactions. In conclusion, 4-oxo-1,4-dihydroquinoline-3-carboxamide derivatives constitute a new class of potent and selective CB(2) cannabinoid receptors agonists.

Crystallography, X-Ray↗

CB1 and CB2 cannabinoid receptor binding studies based on modeling and mutagenesis approaches.

In absence of X ray crystal structures of G-protein coupled receptors (GPCRs)-ligand complexes, computer-aided molecular modeling together with site-directed mutagenesis studies become of great importance in order to provide in-silico predictions that facilitate the development of new ligands. In this context, the present review addresses the application of these strategies to the CB(1) and CB(2) cannabinoid receptors. The combination of these complementary approaches represents a tool of considerable value which has allowed to understand the specific ligand-receptor interactions.

Binding Sites↗

Cannabinoid CB2 receptor activation reduces mouse myocardial ischemia-reperfusion injury: involvement of cytokine/chemokines and PMN.

In this study, we have assessed the activation of the cannabinoid CB2 receptor (CB2-R) in a model of mouse myocardial ischemia/reperfusion (I/R). The results show that treatment of animals with WIN55212-2, a CB1/CB2-R agonist, given 30 min before induction of I/R, significantly reduced the extent of infarct size (IS) in the area at risk, as measured 2.5 h later, with almost a 51% inhibition observed at the dose tested of 3.5 mg/kg intraperitoneally (i.p.). The protective effect of WIN55212-2 was almost abolished by the selective CB2-R antagonist AM630 (1 mg/kg i.p.) and not affected by the selective CB1-R antagonist AM251 (3 mg/kg i.p.). The CB2-R antagonist administered alone produced a slight but significant (P<0.05) increase in IS compared with vehicle alone. The protection afforded by WIN55212-2 was paralleled by lower values of myeloperoxidase activity and interleukin-1beta and of the CXC chemokine ligand 8 into the injured tissue. In conclusion, we demonstrate for the first time that exogenous and endogenous CB2-R activation reduces the leukocyte-dependent myocardial damage associated with an I/R procedure.

Animals↗

Comparison of the pharmacology and signal transduction of the human cannabinoid CB1 and CB2 receptors.

The recently cloned CB2 cannabinoid receptor subtype was stably transfected into AtT-20 and Chinese hamster ovary cells to compare the binding and signal transduction properties of this receptor with those of the CB1 receptor subtype. The binding of [3H]CP 55,940 to both CB1 and CB2 was of similar high affinity (2.6 and 3.7 nM, respectively) and saturable. In competitive binding experiments, (-)-delta 9-tetrahydrocannabinol and CP 55,940 were equipotent at the CB1 and CB2 receptors, but WIN 55212-2 and cannabinol bound with higher affinity to the CB2 than the CB1 receptor. HU 210 had a higher affinity for the CB1 receptor. Anandamide, a recently identified endogenous cannabinoid agonist, was essentially equipotent at both receptor subtypes. The structurally related fatty acid ethanolamides dihomo-gamma-linolenylethanolamide and mead ethanolamide also bound with relatively equal affinity to both receptors, but adrenylethanolamide had a higher affinity for the CB1 receptor. The rank order of potency and efficacy for binding of the selected agonists to the CB1 and CB2 receptors was mimicked in functional inhibition of cAMP accumulation experiments for all compounds tested. Both CB1 and CB2 receptors couple to the inhibition of cAMP accumulation that was pertussis toxin sensitive. SR141716A, a CB1 receptor antagonist, was a poor antagonist at the CB2 receptor in both binding and functional inhibition of cAMP accumulation experiments. When expressed in AtT-20 cells, the CB1 receptor mediated an inhibition of Q-type calcium channels and an activation of inward rectifying potassium channels. In contrast, the CB2 receptor did not modulate the activity of either channel under identical assay conditions. Similar to results obtained for CB1 receptor, the CB2 receptor did not couple to the activation of phospholipases A2, C, or D or to the mobilization of intracellular Ca2+. Except for its inability to couple to the modulation of Q-type calcium channels or inwardly rectifying potassium channels, the CB1 and CB2 receptors display similar pharmacological and biochemical properties.

Adenylyl Cyclase Inhibitors↗

Agonist-inverse agonist characterization at CB1 and CB2 cannabinoid receptors of L759633, L759656, and AM630.

We have tested our prediction that AM630 is a CB2 cannabinoid receptor ligand and also investigated whether L759633 and L759656, are CB2 receptor agonists. Binding assays with membranes from CHO cells stably transfected with human CB1 or CB2 receptors using [3H]-CP55940, confirmed the CB2-selectivity of L759633 and L759656 (CB2/CB1 affinity ratios = 163 and 414 respectively) and showed AM630 to have a Ki at CB2 receptors of 31.2 nM and a CB2/CB1 affinity ratio of 165. In CB2-transfected cells, L759633 and L759656 were potent inhibitors of forskolin-stimulated cyclic AMP production, with EC50 values of 8.1 and 3.1 nM respectively and CB1/CB2 EC50 ratios of > 1000 and > 3000 respectively. AM630 inhibited [35S]-GTPgammaS binding to CB2 receptor membranes (EC50 = 76.6 nM), enhanced forskolin-stimulated cyclic AMP production in CB2-transfected cells (5.2 fold by 1 microM), and antagonized the inhibition of forskolin-stimulated cyclic AMP production in this cell line induced by CP55940. In CB1-transfected cells, forskolin-stimulated cyclic AMP production was significantly inhibited by AM630 (22.6% at 1 microM and 45.9% at 10 microM) and by L759633 at 10 microM (48%) but not 1 microM. L759656 (10 microM) was not inhibitory. AM630 also produced a slight decrease in the mean inhibitory effect of CP55940 on cyclic AMP production which was not statistically significant. We conclude that AM630 is a CB2-selective ligand that behaves as an inverse agonist at CB2 receptors and as a weak partial agonist at CB1 receptors. L759633 and L759656 are both potent CB2-selective agonists.

Animals↗

The cannabinoid CB2 receptor inverse agonist JTE-907 suppresses spontaneous itch-associated responses of NC mice, a model of atopic dermatitis.

JTE-907, N-(benzo[1,3]dioxol-5-ylmethyl)-7-methoxy-2-oxo-8-pentyloxy-1,2-dihydroquinoline-3-carboxamide, is a selective cannabinoid CB2 receptor antagonist/inverse agonist. The anti-pruritic activity of JTE-907 was studied in NC mice with chronic dermatitis, a model of atopic dermatitis. The oral dose of JTE-907 (1 and 10 mg/kg/day), an immunosuppressant agent tacrolimus (1 mg/kg/day) and a glucocorticoid betamethasone 17-valerate (1 mg/kg/day) for 20 days suppressed the spontaneous scratching and cutaneous nerve activity of NC mice. JTE-907 (10, but not 1, mg/kg) and tacrolimus, but not betamethasone, tended to alleviate the dermatitis. Betamethasone inhibited the body weight gain. These results suggest that JTE-907 suppresses spontaneous itch-associated responses of NC mice without adverse effects such as weight loss.

Administration, Oral↗

Regulation of peripheral cannabinoid receptor CB2 phosphorylation by the inverse agonist SR 144528. Implications for receptor biological responses.

We recently demonstrated that the selective cannabinoid receptor antagonist SR 144528 acts as an inverse agonist that blocks constitutive mitogen-activated protein kinase activity coupled to the spontaneous autoactivated peripheral cannabinoid receptor (CB2) in the Chinese hamster ovary cell line stably transfected with human CB2. In the present report, we studied the effect of SR 144528 on CB2 phosphorylation. The CB2 phosphorylation status was monitored by immunodetection using an antibody specific to the COOH-terminal CB2 which can discriminate between phosphorylated and non-phosphorylated CB2 isoforms at serine 352. We first showed that CB2 is constitutively active, phosphorylated, and internalized at the basal level. By blocking autoactivated receptors, inverse agonist SR 144528 treatment completely inhibited this phosphorylation state, leading to an up-regulated CB2 receptor level at the cell surface, and enhanced cannabinoid agonist sensitivity for mitogen-activated protein kinase activation of Chinese hamster ovary-CB2 cells. After acute agonist treatment, serine 352 was extensively phosphorylated and maintained in this phosphorylated state for more than 8 h after agonist treatment. The cellular responses to CP-55,940 were concomitantly abolished. Surprisingly, CP-55,940-induced CB2 phosphorylation was reversed by SR 144528, paradoxically leading to a non-phosphorylated CB2 which could then be fully activated by CP-55,940. The process of CP-55,940-induced receptor phosphorylation followed by SR 144528-induced receptor dephosphorylation kept recurring many times on the same cells, indicating that the agonist switches the system off but the inverse agonist switches the system back on. Finally, we showed that autophosphorylation and CP-55, 940-induced serine 352 CB2 phosphorylation involve an acidotropic GRK kinase, which does not use Gibetagamma. In contrast, SR 144528-induced CB2 dephosphorylation was found to involve an okadaic acid and calyculin A-sensitive type 2A phosphatase.

Amino Acid Sequence↗

Evidence for the presence of CB2-like cannabinoid receptors on peripheral nerve terminals.

We have investigated whether there are cannabinoid CB2 receptors that can mediate cannabinoid-induced inhibition of electrically evoked contractions in the mouse vas deferens or guinea-pig myenteric plexus-longitudinal muscle preparation. Our results showed that mouse vas deferens and guinea-pig whole gut contain cannabinoid CB1 and CB2-like mRNA whereas the myenteric plexus preparation seemed to contain only cannabinoid CB1 mRNA. JWH-015 (1-propyl-2-methyl-3-( -naphthoyl)indole) and JWH-051 (1-deoxy-11-hydroxy-delta8-tetrahydrocannabinol-dimethylheptyl+ ++), which have higher affinities for CB2 than CB1 cannabinoid binding sites, inhibited electrically evoked contractions of both tissues in a concentration related manner. This inhibition was attenuated by 31.62 nM of the cannabinoid CB1 receptor selective antagonist SR141716A [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-me thyl-1H-pyrazole-3-carboxamide hydrochloride] only in the myenteric plexus preparation. Vasa deferentia from delta9-tetrahydrocannabinol-pretreated mice (20 mg/kg i.p. once daily for two days) showed reduced sensitivity to JWH-015 and JWH-051. The results suggest that these compounds exert their inhibitory effects through cannabinoid CB1 receptors in the myenteric plexus preparation, but mainly through CB2-like cannabinoid receptors in the vas deferens.

Amino Acid Sequence↗

AM1241, a cannabinoid CB2 receptor selective compound, delays disease progression in a mouse model of amyotrophic lateral sclerosis.

Effective treatment for amyotrophic lateral sclerosis (ALS) remains elusive. Motor neuron degeneration is the primary pathology in ALS; however non-neuronal cells contribute to the disease process. In particular, inflammatory processes have been shown to play an important role. AM1241 is a cannabinoid CB2 receptor selective agonist that has been shown to be effective in models of inflammation and hyperalgesia. Here we report that treatment with AM1241 was effective at slowing signs of disease progression when administered after onset of signs in an ALS mouse model (hSOD1(G93A) transgenic mice). Administration at the onset of tremors delayed motor impairment in treated mice when compared to vehicle controls. Three conditions of ALS, the loss of motor function, paralysis scoring and weight loss, were analyzed using a mathematical model. Loss of motor function (as assessed by performance on a rotarod) was delayed by 12.5 days in male mice by AM1241. In female mice, AM1241 extended rotarod performance by 3 days, although this was not statistically significant. In male mice, AM1241 also extended by 5 days the time to reach the 50% point on a visually-assessed performance scale. AM1241 did not affect weight loss or survival (129.8+/-1.7 days, vehicle; 129.1+/-7.0 days, AM1241, n=16). As AM1241 was well tolerated by the animals, cannabinoid CB2 receptor-selective compounds may be the basis for developing new drugs for the treatment of ALS and other chronic neurodegenerative diseases.

Amino Acid Substitution↗

Targeting CB2 cannabinoid receptors as a novel therapy to treat malignant lymphoblastic disease.

In the current study, we examined whether ligation of CB2 receptors would lead to induction of apoptosis in tumors of immune origin and whether CB2 agonist could be used to treat such cancers. Exposure of murine tumors EL-4, LSA, and P815 to delta-9-tetrahydrocannabinol (THC) in vitro led to a significant reduction in cell viability and an increase in apoptosis. Exposure of EL-4 tumor cells to the synthetic cannabinoid HU-210 and the endogenous cannabinoid anandamide led to significant induction of apoptosis, whereas exposure to WIN55212 was not effective. Treatment of EL-4 tumor-bearing mice with THC in vivo led to a significant reduction in tumor load, increase in tumor-cell apoptosis, and increase in survival of tumor-bearing mice. Examination of a number of human leukemia and lymphoma cell lines, including Jurkat, Molt-4, and Sup-T1, revealed that they expressed CB2 receptors but not CB1. These human tumor cells were also susceptible to apoptosis induced by THC, HU-210, anandamide, and the CB2-selective agonist JWH-015. This effect was mediated at least in part through the CB2 receptors because pretreatment with the CB2 antagonist SR144528 partially reversed the THC-induced apoptosis. Culture of primary acute lymphoblastic leukemia cells with THC in vitro reduced cell viability and induced apoptosis. Together, the current data demonstrate that CB2 cannabinoid receptors expressed on malignancies of the immune system may serve as potential targets for the induction of apoptosis. Also, because CB2 agonists lack psychotropic effects, they may serve as novel anticancer agents to selectively target and kill tumors of immune origin.

Animals↗

Novel cannabinol probes for CB1 and CB2 cannabinoid receptors.

The observation that the phenolic hydroxyl of THCs was important for binding to the CB1 receptor but not as critical for binding to the CB2 receptor prompted us to extend this finding to the cannabinol (CBN) series. To study the SAR of CBN analogues, CBN derivatives with substitution at the C-1, C-3, and C-9 positions were chosen since these positions have played a key role in the SAR of THCs. CBN-3-(1',1'-dimethylheptyl) analogues were prepared by sulfur dehydrogenation of Delta(8)-THC-3-(1',1'-dimethylheptyl) analogues. 9-Substituted CBN analogues were prepared by the standard sulfur dehydrogenation of 9-substituted Delta(8)-THC analogues (Scheme 1), which in turn were prepared following our previous procedure using selenium dioxide oxidation of the corresponding Delta(8)-THCs followed by sodium chlorite oxidation to give the 9-carboxy-Delta(8)-THC derivatives. 11-Hydroxy-CBN analogues were prepared from the corresponding 9-carbomethoxy-CBN analogues by reduction with LiAlH(4). Deoxy-CBN analogue 14 was prepared from the corresponding Delta(8)-THC analogue 11 by conversion of the phenolic hydroxyl to the phosphate derivative 12, followed by lithium ammonia reduction to provide the deoxy-Delta(8)-THC analogue 13, which in turn was dehydrogenated with sulfur to provide the deoxy-CBN analogue 14 (Scheme 2). The various analogues were assayed for binding both to the brain and the peripheral cannabinoid receptors (CB1 and CB2). We have found that the binding profile differs widely between the CBN and the THC series. Specifically, in the CBN series the removal of the phenolic hydroxyl decreases binding affinity to both the CB1 and CB2 receptors, whereas in the THC series, CB1 affinity is selectively reduced. Thus, in the CBN series, the selectivity of binding observed with the removal of the hydroxy group is decreased severalfold as compared to what occurs in the THC series. Generally, high affinity for the CB2 receptor was found in analogues when the phenolic hydroxyl was present. The 3-(1', 1'-dimethylheptyl) derivatives were found to have much higher affinities than the CBN analogues, which is in complete agreement with previously reported work by Rhee et al.

Animals↗

The endocannabinoid noladin ether acts as a full agonist at human CB2 cannabinoid receptors.

Noladin ether (NE) is a putative endogenously occurring cannabinoid demonstrating agonist activity at CB1 receptors. Because of reported selective affinity for CB1 receptors, the pharmacological actions of NE at CB2 receptors have not been examined. Therefore, the purpose of this study was to characterize the binding and functional properties of NE at human CB2 receptors stably expressed in Chinese hamster ovary (CHO) cells as well as in HL-60 cells, which express CB2 receptors endogenously. Surprisingly, in transfected CHO cells, NE exhibits a relatively high nanomolar affinity for CB2 receptors (K(i) = 480 nM), comparable to that observed for the endocannabinoid 2-arachidonoyl glycerol (2-AG) (K(i) = 1016 nM). Furthermore, NE activates G proteins and inhibits the intracellular effector adenylyl cyclase with equivalent efficacy relative to the full cannabinoid agonists 2-AG and CP 55,940 (CP) [(-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl) cyclohexanol]. The rank order of potency for G protein activation and effector regulation by the three agonists is similar to their apparent affinity for CB2 receptors; CP > NE > or = 2-AG. Regulation of adenylyl cyclase activity by all agonists is inhibited by pertussis toxin pretreatment or by coincubation with AM630 [6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)-methanone], a CB2 antagonist. Chronic treatment with NE or CP results in CB2 receptor desensitization and down-regulation. All agonists also inhibit adenylyl cyclase activity in HL-60 cells. Together, these data indicate that NE acts as a full agonist at human CB2 receptors and thus might have important physiological functions at peripheral cannabinoid receptors.

Adenylyl Cyclase Inhibitors↗

Stereochemical selectivity of methanandamides for the CB1 and CB2 cannabinoid receptors and their metabolic stability.

Several chiral, analogues of the endogenous cannabinoid receptor ligand, arachidonylethanolamide (anandamide), methylated at the 2,1' and 2' positions using asymmetric synthesis were evaluated in order to study (a) stereoselectivity of binding to CB1 and CB2 cannabinoid receptors; and (b) metabolic stability with regard to anandamide amidase. Enantiomerically pure 2-methyl arachidonic acids were synthesized through diastereoselective methylation of the respective chiral 2-oxazolidinone enolate derivatives and CB1 and CB2 receptor affinities of the resulting chiral anandamides were evaluated using a standard receptor binding assay. Introduction of a single 2-methyl group increased affinity for CB1, led to limited enantioselectivity and only modestly improved metabolic stability. However, a high degree of enantio- and diastereoselectivity was observed for the 2,1'-dimethyl analogues. (R)-N-(1-methyl-2-hydroxyethyl)-2-(R)-methyl-arachidonamide (4) exhibited the highest CB1 receptor affinity in this series with a K(i) of 7.42 nM, an at least 10-fold improvement on anandamide (K(i)=78.2 nM). The introduction of two methyl groups at the 2-position of anandamide led to no change in affinity for CB1 but somewhat enhanced metabolic stability. Conversely, chiral headgroup methylation in the 2-gem-dimethyl series led to chiral analogues possessing a wide range of CB1 affinities. Of these the (S)-2,2,2'-trimethyl analogue (12) had the highest affinity for CB1 almost equal to that of anandamide. In agreement with our previous anandamide structure-activity relationship work, the analogues in this study showed high selectivity for the CB1 receptor over CB2. The results are evaluated in terms of stereochemical factors affecting the ligand's affinity for CB1 using receptor-essential volume mapping as an aid. Based on the results, a partial CB1 receptor site model is proposed, that bears two hydrophobic pockets capable of accommodating 1'- and 2-methyl groups

Arachidonic Acids↗

Identification, characterization, and function of a novel oncogene: the peripheral cannabinoid receptor Cb2.

By means of retroviral insertional mutagenesis, we identified a novel common virus integration site (cVIS) (Evi11) in murine leukemias, and demonstrated that Cb2, encoding the peripheral cannabinoid receptor, is the potential proto-oncogene located in that region. Cb2 is a 7-transmembrane G protein-coupled receptor (GPCR), which is normally expressed on B lymphocytes. Using transwell assays we observed strong migration of Cb2-expressing cells upon stimulation with 2-arachidonoylglycerol (2-AG), a potent endocannabinoid. Overexpression of Cb2 receptor on murine myeloid precursor cells causes a block of neutrophilic differentiation, a major characteristic of myeloid leukemia. Intriguingly, we could not detect functional Cb2 receptors on normal murine bone marrow precursor cells. Furthermore, analysis of human acute myeloid leukemia (AML) samples revealed the presence of CB2 mRNA transcripts in several cases. Furthermore, migration could be induced by 2-AG when analyzed in one of the patient samples. Our data suggest that the initially identified cVIS, Evi11, encodes for a murine onco-protein and that human CB2 may be involved in certain cases of human AML as well.

Animals↗