“In the past decades, a vast amount of data accumulated on the role of lipid signaling pathways in the progression of malignant melanoma, the most metastatic/aggressive human cancer type. Genomic studies identified that PTEN loss is the leading factor behind the activation of the PI3K-signaling pathway in melanoma, mutations of which are one of the main resistance mechanisms behind target therapy failures. On the other hand, illegitimate expressions of megakaryocytic genes p12-lipoxyganse, cyclooxygenase-2, and phosphodiestherase-2/autotaxin (ATX) are mostly involved in the regulation of motility signaling in melanoma through various G-protein-coupled bioactive lipid receptors. Furthermore, endocannabinoid signaling can also be a novel paracrine survival factor in melanoma. Last but not least, prenylation inhibitors acting even on mutated small GTP-ases, such as NRAS of melanoma may offer novel therapeutic opportunities. As regards melanoma, the most effective therapy nowadays is immunotherapy, with the resistance mechanisms also possibly involving the lipid signaling activities of melanoma cells, which further supports the idea of their being therapeutic targets.”
Tag Archives: G-Protein coupled receptors
Computational investigation on the binding modes of Rimonabant analogues with CB1 and CB2.
“The human cannabinoid G protein coupled receptor 1 (CB1) is highly expressed in central nervous system. CB1-selective antagonists show therapeutic promise in a wide range of disorders, such as obesity-related metabolic disorders, dyslipidemia, drug abuse and type 2 diabetes.
Rimonabant (SR141716A), MJ08 and MJ15 are selective CB1 antagonists with selectivity >1000 folds over CB2 despite of 42% sequence identity between CB1 and CB2. The integration of homology modeling, automated molecular docking and molecular dynamics simulation were used to investigate the binding modes of these selective inverse agonists/antagonists with CB1 and CB2 and their selectivity.
Our analyses showed that the hydrophobic interactions between ligands and hydrophobic pockets of CB1 account for the main binding affinity. In addition, instead of interacting with ligands directly as previously reported, the Lys1923.28in CB1 was engaged in indirect interactions with ligands to keep inactive-state CB1 stable by forming the salt bridge with Asp1762.63 . Lastly, our analyses indicated that the selectivity of these antagonists came from the difference in geometry shapes of binding pockets of CB1 and CB2.
The present study could guide future experimental works on these receptors and has the guiding significance for the design of functionally selective drugs targeting CB1 or CB2 receptors.”
Is Cannabidiol a Promising Substance for New Drug Development? A Review of its Potential Therapeutic Applications.
“The pharmacological importance of cannabidiol (CBD) has been in study for several years.
CBD is the major nonpsychoactive constituent of plant Cannabis sativa and its administration is associated with reduced side effects.
Currently, CBD is undergoing a lot of research which suggests that it has no addictive effects, good safety profile and has exhibited powerful therapeutic potential in several vital areas.
It has wide spectrum of action because it acts through endocannabinoid receptors; CB1 and CB2 and it also acts on other receptors, such as GPR18, GPR55, GPR 119, 5HT1A, and TRPV2.
This indicates its therapeutic value for numerous medical conditions because of its neuroprotective and immunomodulatory properties.
Potential therapeutic applications of CBD include, analgesic, anti-inflammatory, anxiolytic, anti-arthritic, anti-depressant, anti-Alzheimer disease, anti-ischemic, neuroprotective, and anti-fibrotic.
More promising areas appear to include diabetes and cancer where CBD exhibits lesser side effects and more therapeutic benefits as compared to recent available medical therapies.
Hence, CBD is a promising substance for the development of new drug. However further research and clinical studies are required to explore its complete potential.”
Effects of CB2 and TRPV1 receptors’ stimulation in pediatric acute T-lymphoblastic leukemia
“T-Acute Lymphoblastic Leukemia (T-ALL) is less frequent than B-ALL, but it has poorer outcome. For this reason new therapeutic approaches are needed to treat this malignancy.
The Endocannabinoid/Endovanilloid (EC/EV) system has been proposed as possible target to treat several malignancies, including lymphoblastic diseases. The EC/EV system is composed of two G-Protein Coupled Receptors (CB1 and CB2), the Transient Potential Vanilloid 1 (TRPV1) channel, their endogenous and exogenous ligands and enzymes. CB1 is expressed mainly in central nervous system while CB2 predominantly on immune and peripheral cells, therefore we chose to selectively stimulate CB2 and TRPV1.
We treated T-ALL lymphoblasts derived from 4 patients and Jurkat cells with a selective agonist at CB2 receptor: JWH-133 [100 nM] and an agonist at TRPV1 calcium channel: RTX [5 uM] at 6, 12 and 24 hours. We analyzed the effect on apoptosis and Cell Cycle Progression by a cytofluorimetric assays and evaluated the expression level of several target genes (Caspase 3, Bax, Bcl-2, AKT, ERK, PTEN, Notch-1, CDK2, p53) involved in cell survival and apoptosis, by Real-Time PCR and Western Blotting.
We observed a pro-apoptotic, anti-proliferative effect of these compounds in both primary lymphoblasts obtained from patients with T-ALL and in Jurkat cell line. Our results show that both CB2 stimulation and TRPV1 activation, can increase the apoptosis in vitro, interfere with cell cycle progression and reduce cell proliferation, indicating that a new therapeutic approach to T-cell ALL might be possible by modulating CB2 and TRPV1 receptors.”
http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path%5B%5D=25052
Synergistic interactions between cannabinoid and opioid analgesics.
“Cannabinoids and opioids both produce analgesia through a G-protein-coupled mechanism that blocks the release of pain-propagating neurotransmitters in the brain and spinal cord. However, high doses of these drugs, which may be required to treat chronic, severe pain, are accompanied by undesirable side effects.
Thus, a search for a better analgesic strategy led to the discovery that delta 9-tetrahydrocannabinol (THC), the major psychoactive constituent of marijuana, enhances the potency of opioids such as morphine in animal models.
In addition, studies have determined that the analgesic effect of THC is, at least in part, mediated through delta and kappa opioid receptors, indicating an intimate connection between cannabinoid and opioid signaling pathways in the modulation of pain perception.
A host of behavioral and molecular experiments have been performed to elucidate the role of opioid receptors in cannabinoid-induced analgesia. The aim of such studies is to develop a novel analgesic regimen using low dose combinations of cannabinoids and opioids to effectively treat acute and chronic pain, especially pain that may be resistant to opioids alone.”
Cannabinoid receptor 2: a potential novel therapeutic target for sepsis?
“Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. It is the most common cause of death among critically ill patients in non-coronary intensive care units and the incidence continues to rise. Although advanced management was applied, the prognosis of sepsis patients remains poor.
As a G-protein coupled receptor, cannabinoid receptor 2 (CB2R) was implicated in a wide variety of diseases. In this study, we aimed to investigate the role of CB2R in sepsis.
With the anti-inflammatory and immunomodulatory effects, CB2R is a novel and promising therapeutic target in the management of sepsis. Indeed, specific CB2R agonists have been reported to attenuate leukocyte recruitment, oxidative burst, systemic inflammatory mediator release, bacteremia, and lung tissue damage, while improving survival in different sepsis models.
In addition, autophagy has also been implicated in the protective role of CB2R activation in sepsis. However, almost all of the current outcomes result from animal studies or in vitro cultured cells. Due to the lack of clinical evidence and the ambiguous mechanisms underlying, the clinical application of CB2R stimulation in sepsis is limited. Further studies are needed to delineate the therapeutic effect and the related-pathways of CB2R agonists in sepsis.”
https://www.ncbi.nlm.nih.gov/pubmed/29694303
https://www.tandfonline.com/doi/abs/10.1080/17843286.2018.1461754?journalCode=yacb20
Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System.
“The biological effects of cannabinoids, the major constituents of the ancient medicinal plant Cannabis sativa (marijuana) are mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 (CB1R) and 2. The CB1R is the prominent subtype in the central nervous system (CNS) and has drawn great attention as a potential therapeutic avenue in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Furthermore, cannabinoids also modulate signal transduction pathways and exert profound effects at peripheral sites. Although cannabinoids have therapeutic potential, their psychoactive effects have largely limited their use in clinical practice. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, focusing on the CB1R and the CNS, with emphasis on recent breakthroughs in the field. We aim to define several potential roles of cannabinoid receptors in the modulation of signaling pathways and in association with several pathophysiological conditions. We believe that the therapeutic significance of cannabinoids is masked by the adverse effects and here alternative strategies are discussed to take therapeutic advantage of cannabinoids.”
Absence of cannabinoid 1 receptor in beta cells protects against high-fat/high-sugar diet-induced beta cell dysfunction and inflammation in murine islets.
“The cannabinoid 1 receptor (CB1R) regulates insulin sensitivity and glucose metabolism in peripheral tissues. CB1R is expressed on pancreatic beta cells and is coupled to the G protein Gαi, suggesting a negative regulation of endogenous signalling in the beta cell.
To assess the direct contribution of beta cell CB1R to metabolism, we designed a mouse model that allows us to determine the role of CB1R specifically in beta cells in the context of whole-body metabolism.
CONCLUSIONS/INTERPRETATION:
Our data demonstrate CB1R to be a negative regulator of beta cell function and a mediator of islet inflammation under conditions of metabolic stress. Our findings point to beta cell CB1R as a therapeutic target, and broaden its potential to include anti-inflammatory effects in both major forms of diabetes.”
https://www.ncbi.nlm.nih.gov/pubmed/29497784
https://link.springer.com/article/10.1007%2Fs00125-018-4576-4
Targeting the endocannabinoid system as a potential anticancer approach.
“The endocannabinoid system is currently under intense investigation due to the therapeutic potential of cannabinoid-based drugs as treatment options for a broad variety of diseases including cancer.
Besides the canonical endocannabinoid system that includes the cannabinoid receptors CB1 and CB2 and the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol, recent investigations suggest that other fatty acid derivatives, receptors, enzymes, and lipid transporters likewise orchestrate this system as components of the endocannabinoid system when defined as an extended signaling network.
As such, fatty acids acting at cannabinoid receptors (e.g. 2-arachidonoyl glyceryl ether [noladin ether], N-arachidonoyldopamine) as well as endocannabinoid-like substances that do not elicit cannabinoid receptor activation (e.g. N-palmitoylethanolamine, N-oleoylethanolamine) have raised interest as anticancerogenic substances.
Furthermore, the endocannabinoid-degrading enzymes fatty acid amide hydrolase and monoacylglycerol lipase, lipid transport proteins of the fatty acid binding protein family, additional cannabinoid-activated G protein-coupled receptors, members of the transient receptor potential family as well as peroxisome proliferator-activated receptors have been considered as targets of antitumoral cannabinoid activity. Therefore, this review focused on the antitumorigenic effects induced upon modulation of this extended endocannabinoid network.” https://www.ncbi.nlm.nih.gov/pubmed/29390896 http://www.tandfonline.com/doi/abs/10.1080/03602532.2018.1428344?journalCode=idmr20
LH-21 and Abn-CBD improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling.
“CB1 and GPR55 are GPCRs expressed by islet β-cells. Pharmacological compounds have been used to investigate their function, but off-target effects of ligands have been reported.
This study examined the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and islets from GPR55-/- mice were used to determine signalling via GPR55.
RESULTS:
Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca2+ ]i in human islets and islets from both GPR55+/+ and GPR55-/- mice. LH-21 also increased insulin secretion and [Ca2+ ]i in human islets and GPR55+/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55-/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55+/+ mouse islets, and these effects were suppressed following GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55-/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets.
CONCLUSIONS:
This study demonstrated that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55-/- mice suggests that designation of Abn-CBD and LH-21 as GPR55 agonist and CB1 antagonist, should be revised.”
https://www.ncbi.nlm.nih.gov/pubmed/29205751
http://onlinelibrary.wiley.com/doi/10.1111/dom.13180/abstract