Monoacylglycerol lipase (MGL) is a serine hydrolase that plays a major role in the degradation of endogenous cannabinoid 2-arachidonoylglycerol. The role of MGL in some cancer cells has been confirmed, where inhibition of the MGL activity shows inhibition on cell proliferation. This makes MGL a promising drug target for the treatment of cancer. Recently, the development of covalent inhibitors of MGL has developed rapidly. These drugs have strong covalent binding ability, high affinity, long duration, low dose and low risk of drug resistance, so they have received increasing attention. This article introduces the structure and function of MGL, the characteristics, mechanisms and progress of covalent MGL inhibitors, providing reference for the development of novel covalent small molecule inhibitors of MGL.
Monoacylglycerol Lipases/metabolism* ; Endocannabinoids/metabolism*

Cannabinoid Receptor Modulators ; Endocannabinoids ; Humans ; Metabolic Syndrome ; metabolism

Being a great threaten for human health, obesity has become a pandemic chronic disease. There have been several therapeutic treatments for this social health issue, including diet and exercise therapy, medication and surgery, among which the diet is still the most common way. However, none of these therapeutic measures available is ideal, making it necessary to find an effective medical treatment. The endocannabinoid system, which is well known for its contributions in certain mental processes such as relaxation, amelioration of pain and anxiety, and sedation initiation, has been recently reported to play an essential role in regulating appetite and metabolism to maintain energy balance, leading to the belief that endocannabinoid system is closely related to obesity. This new discovery deepens our understanding of obesity, and provides us with a new direction for clinical obesity treatment. Rimonabant is an antagonist for CB1, and has entered the market in some countries. However, although effective as an anti-obesity drug, rimonabant also causes obviously adverse side-effects, thus is being doubted and denied for medical usage.
Animals ; Anti-Obesity Agents ; therapeutic use ; Cannabinoid Receptor Modulators ; antagonists & inhibitors ; metabolism ; Endocannabinoids ; Humans ; Obesity ; drug therapy ; metabolism ; Piperidines ; therapeutic use ; Pyrazoles ; therapeutic use ; Receptors, Cannabinoid ; metabolism

This study examined endogenous cannabinoid (ECB)-anandamide (AEA) and its cannabinoid receptors (CBR) in mice liver with the development of schistosoma japonicum. Mice were infected with schistosoma by means of pasting the cercaria onto their abdomens. Liver fibrosis was pathologically confirmed nine weeks after the infection. High performance liquid chromatography (HPLC) was employed to determine the concentration of AEA in the plasma of mice. Immunofluorescence was used to detect the expression of CBR1 and CBR2 in liver tissue. Morphological examination showed typical pathological changes, with worm tubercles of schistosoma deposited in the liver tissue, fibrosis around the worm tubercles and infiltration or soakage of inflammatory cells. Also, CBR1 and CBR2 were present in hepatocytes and hepatic sinusoids of the two groups, but they were obviously enhanced in the schistosoma-infected mice. However, the average optical density of CBR1 in the negative control and fibrosis group was 13.28+/-7.32 and 30.55+/-7.78, and CBR2 were 28.13+/-6.42 and 52.29+/-4.24 (P<0.05). The levels of AEA in the fibrosis group were significantly increased as compared with those of the control group. The concentrations of AEA were (0.37+/-0.07) and (5.67+/-1.34) ng/mL (P<0.05). It is concluded that the expression of endocannabinoids AEA and its cannabinoid receptor CBR were significantly increased in schistosoma-infected mice. Endogenous endocannabinoids may be involved in the development of schistosoma-induced liver fibrosis.
Arachidonic Acids/*metabolism ; Endocannabinoids/*metabolism ; Liver Cirrhosis/etiology ; Liver Cirrhosis/*metabolism ; Liver Cirrhosis/parasitology ; Polyunsaturated Alkamides/*metabolism ; Random Allocation ; Receptor, Cannabinoid, CB1/*metabolism ; Receptor, Cannabinoid, CB2/*metabolism ; Schistosomiasis japonica/*complications ; Schistosomiasis japonica/metabolism

OBJECTIVETo study the effects of endogenous cannabinoid anandamide (AEA) and its putative endocannabinoid receptors (CBR) on the activation and proliferation of hepatic stellate cells (HSC) and to study the role played by AEA during liver fibrosis.

METHODSBy using immunofluorescence and cell culture, the expression of CBR 1 and 2 in the PDGF-stimulated HSCs was investigated. By using PCR and Western-blot, the effects of 10, 20mumol/L AEA and CBR2 antagonist AM630 on the cultured and activated HSC were observed. Methyl thiazolyl tetrazolium and flow cytometry were used to investigate whether AEA induces growth inhibition or apoptosis in the activated HSCs.

RESULTSBoth CBR1 and CBR2 receptors were detectable in cultured HSCs with a higher level of CBR2 than CBR1 (F = 116.797, P less than 0.01). When HSCs were stimulated by PDGF, the expression of CBR2 receptors was significantly enhanced (F = 7.878, P less than 0.05). HSC proliferation was dose-dependently inhibited by 10, 20, and 50micromol/L AEA, with the rates of 7.12%+/-0.34%, 12.52%+/-0.78%, 80.13%+/-1.57% respectively (F = 533.41, P less than 0.01). However, it did not induce apoptosis, but necrosis. The expressions of alpha-SMA, TGFb1, a1(I), a1(III) and TIMP-1 were significantly suppressed by 20micromol/L AEA, but CBR2 antagonist AM630 reversed this suppressor action of AEA.

CONCLUSIONSAEA may inhibit activation and proliferation of HSCs; CBR2 receptors mediate AEA-induced inhibitory action on the activation of HSCs. This CBR2 receptor-mediated action and AEA on HSCs could be used as a therapeutic target against liver fibrosis.

Animals ; Arachidonic Acids ; pharmacology ; Cannabinoid Receptor Modulators ; pharmacology ; Cell Proliferation ; drug effects ; Cells, Cultured ; Endocannabinoids ; Hepatic Stellate Cells ; cytology ; drug effects ; metabolism ; Indoles ; pharmacology ; Polyunsaturated Alkamides ; pharmacology ; Rats ; Receptor, Cannabinoid, CB2 ; metabolism

OBJECTIVETo study the effect of anandamide (AEA) on necrosis in HepG2 cells and to explore the role of AEA in progression of liver cancer.

METHODSLocalization of the fatty acid hydrolytic enzyme (FAAH), cannabinoid receptors 1(CB1) and cannabinoid receptors 2 (CB2) proteins was detected in L02 and HepG2 cells using immunofluorescence. L02 and HepG2 cells were treated with different concentrations of AEA and methyl-beta-cyclodextrin, and the rates of cells necrosis were examined by PI stain. Meanwhile, the expression levels of FAAH, CB1 and CB2 receptor proteins, as well as P38 mitogen-activated protein kinase (p-P38 MAPK) and c-Jun-NH2-terminal kinase (p-JNK) proteins, were analyzed by Western blot.

RESULTSThe FAAH, CB1 and CB2 receptor proteins were observed both in cytoplasm and on membrane in L02 and HepG2 cells. The expression level of FAAH protein was higher in HepG2 than in L02 cells. The expression level of CB1 receptor protein was very low in both L02 and HepG2 cells. The expression level of CB2 receptor protein was high in both L02 and HepG2 cells. AEA treatment induced necrosis in HepG2 cells but not in L02 cells. Methyl-beta-cyclodextrin treatment prevented necrosis in HepG2 cells (t = 3.702; 5.274; 3.503, P less than 0.05). The expression patterns of FAAH, CB1 and CB2 receptor protein in L02 and HepG2 cells were confirmed by western blot, which were consistent with the immunofluorescence results. AEA treatment increased the levels of p-P38MAPK and p-JNK proteins in a dose-dependent manner in HepG2 cells (F = 11.908; 26.054, P less than 0.05) and the increase can be partially by prevented by MCD (t = 2.801; t = 12.829, P less than 0.05).

CONCLUSIONAEA treatment induces necrosis in HepG2 cells via CB1 and CB2 receptors and lipid rafts.

Amidohydrolases ; metabolism ; Arachidonic Acids ; pharmacology ; Cannabinoid Receptor Modulators ; pharmacology ; Cholesterol ; metabolism ; Endocannabinoids ; Hep G2 Cells ; Humans ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Necrosis ; Polyunsaturated Alkamides ; pharmacology ; Receptor, Cannabinoid, CB1 ; metabolism ; Receptor, Cannabinoid, CB2 ; metabolism ; Signal Transduction ; beta-Cyclodextrins ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; metabolism

To observe a PPAR-alpha agonist effect of N-oleoylethanolamine (OEA) on CB2 (cannabinoid receptor 2), an anti-inflammatory receptor in vascular endothelial cell, healthy HUVECs and TNF-alpha induced HUVECs were used to establish a human vascular endothelial cell inflammatory model. Different doses of OEA (10, 50 and 100 micromol x L(-1)) had been given to HUVECs, cultured at 37 degrees C for 7 h and then collected the total protein and total mRNA. CB2 protein expression was detected by Western blotting and CB2 mRNA expression was assayed by real-time PCR. As the results shown, OEA (10 and 50 micromol x L(-1)) could induce the CB2 protein and mRNA expression, but not 100 micromol x L(-1). To detect if anti-inflammation effect of OEA is partly through CB2, CB2 inhibitor AM630 was used to inhibit HUVEC CB2 expression, then the VCAM-1 expression induced by TNF-alpha was detected, or THP-1 adhere to TNF-alpha induced HUVECs was examined. OEA (50 micromol x L(-1)) could inhibit TNF-alpha induced VCAM-1 expression and THP-1 adhere to HUVECs, these effects could be partly inhibited by a CB2 inhibitor AM630. The anti-inflammation effect of OEA is induced by PPAR-alpha and CB2, suggesting that CB2 signaling could be a target for anti-atherosclerosis, OEA have wide effect in anti-inflammation, it may have better therapeutic potential in anti-inflammation in HUVECs, thus achieving anti-atherosclerosis effect.
Anti-Inflammatory Agents ; pharmacology ; Atherosclerosis ; pathology ; Cell Adhesion ; drug effects ; Cells, Cultured ; Endocannabinoids ; pharmacology ; Endothelial Cells ; cytology ; metabolism ; Ethanolamines ; pharmacology ; Humans ; Indoles ; pharmacology ; Monocytes ; drug effects ; Oleic Acids ; pharmacology ; PPAR alpha ; antagonists & inhibitors ; RNA, Messenger ; metabolism ; Receptor, Cannabinoid, CB2 ; antagonists & inhibitors ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; pharmacology ; Vascular Cell Adhesion Molecule-1 ; metabolism

OBJECTIVETo study the influences of endocannabinoid-anandamide (AEA) on the proliferation and apoptosis of the colorectal cancer cell line (CaCo-2) and to elucidate the effects of CB1 and lipid rafts, and to further elucidate the molecular mechanism and the effect of AEA on the generation and development of colorectal cancer.

METHODSHuman colorectal cancer cell line CaCo-2 was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum in 5% CO(2) atmosphere at 37°C. CaCo-2 cells were divided into different groups and treated with different concentrations of AEA, AEA + SR141716A, AEA + AM630 and AEA + methyl-β-cyclodextrin (MCD). MTT assay was used to determine the effects of AEA, its putative CB1, CB2 receptor antagonists (SR141716A and AM630) and MCD on the proliferation of CaCo-2 cells. Annexin V-PE/7AAD binding assay was used to detect apoptosis in the CaCo-2 cells. Western-blot was applied to check the expressions of CB1, CB2, p-AKT and caspase-3 proteins in different groups of CaCo-2 cells.

RESULTSAEA inhibited the proliferation of CaCo-2 cells in a concentration-dependent manner and the effect could be antagonized by SR141716A and MCD. The inhibiting rates were (21.52 ± 0.45)%, (42.16 ± 0.21)%, (73.64 ± 0.73)% and (83.28 ± 0.71)%, respectively, at different concentrations of AEA (5, 10, 20 and 40 µmol/L). The three groups (20 µmol/L AEA, 20 µmol/L AEA + 10 µmol/L SR141716A and 20 µmol/L AEA + 1 mmol/L MCD) showed different inhibiting rates [(73.64 ± 0.73)%, (16.15 ± 0.75)% and (12.58 ± 0.63)%], respectively. Annexin V-PE/7AAD binding assay showed that AEA induced apoptosis in the CaCo-2 cells and MCD could antagonize this effect. The apoptosis rates of the three groups (control, 20 µmol/L AEA and 20 µmol/L AEA + 1 mmol/L MCD) were (2.95 ± 0.73)%, (39.61 ± 0.73)% and (14.10 ± 0.64)%, respectively. The expressions of CB1, CB2, p-AKT and Caspase-3 proteins were all observed in the CaCo-2 cells. AEA inhibited p-AKT protein expression and induced caspase-3 protein expression. The two actions were also antagonized by MCD.

CONCLUSIONSAEA can strongly suppress the proliferation of colorectal cancer CaCo-2 cells via the CB1 receptor and membrane cholesterol-LRs and induce apoptosis via lipid rafts. Anandamide plays a very important role in the carcinogenesis and development of colorectal cancer. MCD is a critical member in this system.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Arachidonic Acids ; antagonists & inhibitors ; pharmacology ; Caco-2 Cells ; Cannabinoid Receptor Modulators ; antagonists & inhibitors ; pharmacology ; Caspase 3 ; metabolism ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Endocannabinoids ; Humans ; Indoles ; pharmacology ; Membrane Microdomains ; metabolism ; Piperidines ; pharmacology ; Polyunsaturated Alkamides ; antagonists & inhibitors ; pharmacology ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrazoles ; pharmacology ; Receptor, Cannabinoid, CB1 ; antagonists & inhibitors ; metabolism ; Receptor, Cannabinoid, CB2 ; antagonists & inhibitors ; metabolism ; beta-Cyclodextrins ; metabolism

Endocannabinoid anandamide (AEA) has protective effect on the heart against ischemia/reperfusion injury and arrhythmia, but the electrophysiological mechanism is unclear yet. In this study, the sinoatrial node (SAN) samples from New Zealand rabbits were prepared, and intracellular recording technique was used to elucidate the effect of AEA on the action potential (AP) of SAN pacemaker cells of rabbits and the mechanism. Different concentrations of AEA (1, 10, 100, 200, 500 nmol/L) were applied cumulatively. For some SAN samples, cannabinoid type 1 (CB1) receptor antagonist AM251, cannabinoid type 2 (CB2) receptor antagonist AM630, potassium channel blocker tetraethylammonium (TEA) and nitric oxide (NO) synthase inhibitor L-nitro-arginine methylester (L-NAME) were used before AEA treatment, respectively. We found that: (1) AEA (100, 200 and 500 nmol/L) not only shortened AP duration (APD), but also decreased AP amplitude (APA) (P < 0.05). (2) AM251, but not AM630, abolished the effect of AEA on APD shortening. (3) TEA and L-NAME had no influence on the AEA effect. These findings suggest that anandamide can decrease APA and shorten APD in SAN pacemaker cells of rabbits, which may be mediated by activation of CB1 receptors, and is related to blockade of calcium channels but not potassium channels and NO.
Action Potentials ; Animals ; Arachidonic Acids ; pharmacology ; Cannabinoid Receptor Antagonists ; pharmacology ; Endocannabinoids ; pharmacology ; Indoles ; pharmacology ; Myocytes, Cardiac ; drug effects ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; metabolism ; Piperidines ; pharmacology ; Polyunsaturated Alkamides ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Pyrazoles ; pharmacology ; Rabbits ; Sinoatrial Node ; cytology