Study of cannabinoid receptor 2 Q63R gene polymorphism in Lebanese patients with rheumatoid arthritis.

 

“The cannabinoid (CB) receptor 2, primarily expressed in immune cells, was shown to play important immune-regulatory functions. In particular, the CB2-R63 functional variant has been shown to alter the ability of the CB2 receptor to exert its inhibitory function on T lymphocytes.

The aim of this study was to investigate the association between a common dinucleotide polymorphism, Q63R, in the cannabinoid receptor 2 gene (CNR2) and rheumatoid arthritis (RA) in the Lebanese population.

One hundred five unrelated Lebanese RA patients and one hundred five controls from different Lebanese governorates were recruited in this study. Genomic DNA was extracted, polymerase chain reaction was performed, and CNR2 was genotyped in a blinded fashion. The χ2 test was used to determine the differences in genotypes and allele frequencies. CNR2 genotyping showed significantly higher frequencies of the CB2-R63 variant (allele frequencies, P < 0.00001; genotype distribution, P < 0.00001) in RA patients when compared with healthy controls. Moreover, RR carriers had more than 10-fold risk for developing RA (OR = 10.8444, 95% CI = 5.0950-23.0818; P < 0.0001), and QR carriers had more than 3-fold risk (OR = 3.8667, 95% CI = 1.7886-8.3591; P = 0.0006) as compared with QQ carriers.

Our preliminary results suggest a role of CB2-Q63R gene polymorphism in the etiology of RA, thus supporting its potential use as a pharmacological target for selective agonists in clinical practice.”

https://www.ncbi.nlm.nih.gov/pubmed/30032418

https://link.springer.com/article/10.1007%2Fs10067-018-4217-9

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Cannabinoid receptor 1/2 double-knockout mice develop epilepsy.

Epilepsia

“The endocannabinoid system has gained attention as an important modulator of activity in the central nervous system. Initial studies focused on cannabinoid receptor 1 (CB1), which is widely expressed in the brain, but recent work also implicates cannabinoidreceptor 2 (CB2) in modulating neuronal activity.

Both receptors are capable of reducing neuronal activity, generating interest in cannabinoid receptor agonists as potential anticonvulsants.

CB1 (Cnr1) and CB2 (Cnr2) single-knockout mice have been generated, with the former showing heightened seizure sensitivity, but not overt seizures. Given overlapping and complementary functions of CB1 and CB2 receptors, we queried whether double-knockout mice would show an exacerbated neurological phenotype.

Strikingly, 30% of double-knockout mice exhibited provoked behavioral seizures, and 80% were found to be epileptic following 24/7 video-electroencephalographic monitoring. Single-knockout animals did not exhibit seizures. These findings highlight the importance of the endocannabinoid system for maintaining network stability.”

https://www.ncbi.nlm.nih.gov/pubmed/29105060

http://onlinelibrary.wiley.com/doi/10.1111/epi.13930/abstract

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Polymorphism rs3123554 in the cannabinoid receptor gene type 2 (CNR2) reveals effects on body weight and insulin resistance in obese subjects.

Endocrinología, Diabetes y Nutrición

“Few studies assessing the relationship between single nucleotide polymorphisms in CNR2 and obesity or its related metabolic parameters are available.

OBJECTIVE:

To investigate the influence of polymorphism rs3123554 in the CNR2 receptor gene on obesity anthropometric parameters, insulin resistance, and adipokines in subjects with obesity.

DESIGN:

The study population consisted of 1027 obese subjects, who were performed bioelectrical impedance analyses, blood pressure measurements, serial assessments of dietary intake during three days, and biochemical tests.

RESULTS:

Genotypes GG, GA, and AA were found in 339 (33.0%), 467 (45.5%), and 221 (21.5%) respectively. Body mass index, weight, fat mass, waist circumference, insulin, HOMA-IR, and triglyceride and leptin levels were higher in A-allele carriers as compared to non A-allele carriers. No differences were seen in these parameters between the GA and AA genotypes. There were no statistical differences in dietary intake.

CONCLUSION:

The main study finding was the association of the minor allele of the SNP rs3123554 in the CNR2 gene with body weight and triglyceride, HOMA-IR, insulin, and leptin levels.”

https://www.ncbi.nlm.nih.gov/pubmed/28895540

http://www.sciencedirect.com/science/article/pii/S2530016417301799?via%3Dihub

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Combined deficiency of the Cnr1 and Cnr2 receptors protects against age-related bone loss by osteoclast inhibition.

Aging Cell

“The endocannabinoid system plays a role in regulating bone mass and bone cell activity and inactivation of the type 1 (Cnr1) or type 2 (Cnr2) cannabinoid receptors influences peak bone mass and age-related bone loss. As the Cnr1 and Cnr2 receptors have limited homology and are activated by different ligands, we have evaluated the effects of combined deficiency of Cnr1 and 2 receptors (Cnr1/2-/- ) on bone development from birth to old age and studied ovariectomy induced bone loss in female mice. The Cnr1/2-/- mice had accelerated bone accrual at birth when compared with wild type littermates, and by 3 months of age, they had higher trabecular bone mass. They were also significantly protected against ovariectomy-induced bone loss due to a reduction in osteoclast number. The Cnr1/2-/- mice had reduced age-related bone loss when compared with wild-type due to a reduction in osteoclast number. Although bone formation was reduced and bone marrow adiposity increased in Cnr1/2-/- mice, the osteoclast defect outweighed the reduction in bone formation causing preservation of bone mass with aging. This contrasts with the situation previously reported in mice with inactivation of the Cnr1 or Cnr2 receptors individually where aged-related bone loss was greater than in wild-type. We conclude that the Cnr1 and Cnr2 receptors have overlapping but nonredundant roles in regulating osteoclast and osteoblast activities. These observations indicate that combined inhibition of Cnr1 and Cnr2 receptors may be beneficial in preventing age-related bone loss, whereas blockade of individual receptors may be detrimental.”

https://www.ncbi.nlm.nih.gov/pubmed/28752643

http://onlinelibrary.wiley.com/doi/10.1111/acel.12638/abstract

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Sativex® effects on promoter methylation and on CNR1/CNR2 expression in peripheral blood mononuclear cells of progressive multiple sclerosis patients.

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“Multiple sclerosis (MS) is a chronic demyelinating central nervous system (CNS) disease that involve oligodendrocyte loss and failure to remyelinate damaged brain areas causing a progressive neurological disability.

Studies in MS mouse model suggest that cannabinoids ameliorate symptoms as spasticity, tremor and pain reducing inflammation via cannabinoid-mediated system.

The aim of our study is to investigate the changes in cannabinoid type 1 (CNR1) and 2 (CNR2) receptors mRNA expression levels and promoter methylation in peripheral blood mononuclear cells (PBMCs) of MS secondary progressive (MSS-SP) patients treated with Sativex®.

These results suggest that the different expression of cannabinoid receptors by Sativex® treatment in leukocytes might be regulated through a molecular mechanism that involve interferon modulation.”

https://www.ncbi.nlm.nih.gov/pubmed/28716266

http://www.jns-journal.com/article/S0022-510X(17)30392-1/fulltext

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Emerging therapeutic targets in cancer induced bone disease: A focus on the peripheral type 2 cannabinoid receptor.

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“Skeletal complications are a common cause of morbidity in patients with primary bone cancer and bone metastases. The type 2 cannabinoid (Cnr2) receptor is implicated in cancer, bone metabolism and pain perception. Emerging data have uncovered the role of Cnr2 in the regulation of tumour-bone cell interactions and suggest that agents that target Cnr2 in the skeleton have potential efficacy in the reduction of skeletal complications associated with cancer.

This review aims to provide an overview of findings relating to the role of Cnr2 receptor in the regulation of skeletal tumour growth, osteolysis and bone pain, and highlights the many unanswered questions and unmet needs.

This review argues that development and testing of peripherally-acting, tumour-, Cnr2-selective ligands in preclinical models of metastatic cancer will pave the way for future research that will advance our knowledge about the basic mechanism(s) by which the endocannabinoid system regulate cancer metastasis, stimulate the development of a safer cannabis-based therapy for the treatment of cancer and provide policy makers with powerful tools to assess the science and therapeutic potential of cannabinoid-based therapy.

Thus, offering the prospect of identifying selective Cnr2 ligands, as novel, alternative to cannabis herbal extracts for the treatment of advanced cancer patients.”

https://www.ncbi.nlm.nih.gov/pubmed/28274851

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[The endocannabinoid system and bone].

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“Recent studies suggest an important role for the skeletal endocannabinoid system in the regulation of bone mass in both physiological and pathological conditions. Both major endocannabinoids (anandamid and 2-arachidonoylglycerol), endocannabinoid receptors – CB1-receptor (CB1R) a CB2-receptor (CB2R) and the endocannabinoid metabolizing enzymes are present or expressed in osteoblasts and osteoclasts. Previous studies identified multiple risk and protective variants of CNR2 gene dealing with the relationship to bone density and/or osteoporosis. Selective CB1R/ CB2R-inverse agonists/antagonists and CB2R-inverse agonists/antagonists are candidates for prevention of bone mass loss and combined antiresorptive and anabolic therapy for osteoporosis.”

https://www.ncbi.nlm.nih.gov/pubmed/27734700

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Mechanical and material properties of cortical and trabecular bone from cannabinoid receptor-1-null (Cnr1-/-) mice.

“The endocannabinoid system is known for its regulatory effects on bone metabolism through the cannabinoid receptors, Cnr1 and Cnr2. In this study we analysed the mechanical and material properties of long bones from Cnr1-/- mice on a C57BL/6 background. Tibiae and femora from 5- and 12-week-old mice were subjected to three-point bending to measure bending stiffness and yield strength. Elastic modulus, density and mineral content were measured in the diaphysis. Second moment of area (MOA2), inner and outer perimeters of the cortical shaft and trabecular fractional bone volume (BV/TV) were measured using micro-CT. In Cnr1-/- males and females at both ages the bending stiffness was reduced due to a smaller MOA2. Bone from Cnr1-/- females had a greater modulus than wild-type controls, although no differences were observed in males. BV/TV of 12-week-old Cnr1-/- females was greater than controls, although no difference was seen at 5-weeks. On the contrary, Cnr1-/- males had the same BV/TV as controls at 12-weeks while they had significantly lower values at 5-weeks. This study shows that deleting Cnr1 decreases the amount of cortical bone in both males and females at 12-weeks, but increases the amount of trabecular bone only in females.”

http://www.ncbi.nlm.nih.gov/pubmed/27401043

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Cannabinoid Receptors Are Overexpressed in CLL but of Limited Potential for Therapeutic Exploitation.

“The cannabinoid receptors 1 and 2 (CNR1&2) are overexpressed in a variety of malignant diseases and cannabinoids can have noteworthy impact on tumor cell viability and tumor growth.

Patients diagnosed with chronic lymphocytic leukemia (CLL) present with very heterogeneous disease characteristics translating into highly differential risk properties.

To meet the urgent need for refinement in risk stratification at diagnosis and the search for novel therapies we studied CNR expression and response to cannabinoid treatment in CLL.

Expression levels of CNR1&2 were determined in 107 CLL patients by real-time PCR and analyzed with regard to prognostic markers and survival.

In contrast to other tumor entities, our data suggest a limited usability of cannabinoids for CLL therapy. Nonetheless, we could define CNR1 mRNA expression as novel prognostic marker.”

http://www.ncbi.nlm.nih.gov/pubmed/27248492

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Novel role of cannabinoid receptor 2 in inhibiting EGF/EGFR and IGF-I/IGF-IR pathways in breast cancer.

Image result for Oncotarget.“Breast cancer is the second leading cause of cancer deaths among women.

Cannabinoid receptor 2 (CNR2 or CB2) is an integral part of the endocannabinoid system.

Although CNR2 is highly expressed in the breast cancer tissues as well as breast cancer cell lines, its functional role in breast tumorigenesis is not well understood.

We observed that estrogen receptor-α negative (ERα-) breast cancer cells highly express epidermal growth factor receptor (EGFR) as well as insulin-like growth factor-I receptor (IGF-IR). We also observed IGF-IR upregulation in ERα+ breast cancer cells.

In addition, we found that higher CNR2 expression correlates with better recurrence free survival in ERα- and ERα+ breast cancer patients.

Our studies showed that CNR2 activation inhibited EGF and IGF-I-induced migration and invasion of ERα+ and ERα- breast cancer cells.

In conclusion, we show that CNR2 activation suppresses breast cancer through novel mechanisms by inhibiting EGF/EGFR and IGF-I/IGF-IR signaling axes.”

http://www.ncbi.nlm.nih.gov/pubmed/27213582

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