cannabidiol and lysophosphatidylinositol

Non-alcoholic fatty liver disease is recognized as the leading cause of chronic liver disease. Overnutrition and obesity are associated with hepatic steatosis. G protein-coupled receptor 55 (GPR55) has not been extensively studied in hepatic steatosis, although its endogenous ligands have been implicated in liver disease progression. Therefore, the functions of GPR55 were investigated in Hep3B human hepatoma cells and mice fed high-fat diets. O-1602, the most potent agonist of GPR55, induced lipid accumulation in hepatocytes, which was reversed by treatment with CID16020046, an antagonist of GPR55. O-1602 also induced intracellular calcium rise in Hep3B cells in a GPR55-independent manner. O-1602-induced lipid accumulation was dependent on the PI3 kinase/Akt/SREBP-1c signaling cascade. Furthermore, we found increased levels of lysophosphatidylinositol species of 16:0, 18:0, 18:1, 18:2, 20:1, and 20:2 in the livers of mice fed a high-fat diet for 4 weeks. One-week treatment with CID16020046 suppressed high-fat diet-induced lipid accumulation and O-1602-induced increase of serum triglyceride levels in vivo. Therefore, the present data suggest the pro-steatotic function of GPR55 signaling in hepatocytes and provide a potential therapeutic target for non-alcoholic fatty liver disease.

Topics: Animals; Azabicyclo Compounds; Benzoates; Calcium; Cannabidiol; Diet, High-Fat; Hep G2 Cells; Humans; Intracellular Space; Lipids; Liver; Lysophospholipids; Mice; Models, Biological; Non-alcoholic Fatty Liver Disease; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Receptors, Cannabinoid; Signal Transduction; Sterol Regulatory Element Binding Protein 1; Triglycerides

Tumour cell migration and adhesion constitute essential features of metastasis. G-protein coupled receptor 55 (GPR55), a lysophospholipid receptor, has been shown to play an important role in carcinogenesis. Here, we investigated the involvement of GPR55 in migration and metastasis of colon cancer cells.. Adhesion and migration assays using the highly metastatic colon cancer cell line HCT116 and an in vivo assay of liver metastasis were performed. The GPR55 antagonist CID16020046, cannabidiol, a putative GPR55 antagonist and GPR55 siRNA were used to block GPR55 activity in HCT116 colon cancer cells.. HCT116 cells showed a significant decrease in adhesion to endothelial cells and in migration after blockade with CID16020046 or cannabidiol. The inhibitory effects of CID16020046 or cannabidiol were averted by GPR55 siRNA knock down in cancer cells. The integrity of endothelial cell monolayers was increased after pretreatment of HCT116 cells with the antagonists or after GPR55 siRNA knockdown while pretreatment with lysophosphatidylinositol (LPI), the endogenous ligand of GPR55, decreased integrity of the monolayers. LPI also induced migration in GPR55 overexpressing HCT116 cells that was blocked by GPR55 antagonists. In a mouse model of metastasis, the arrest of HCT116 cancer cells in the liver was reduced after treatment with CID16020046 or cannabidiol. Increased levels of LPI (18:0) were found in colon cancer patients when compared with healthy individuals.. GPR55 is involved in the migratory behaviour of colon carcinoma cells and may serve as a pharmacological target for the prevention of metastasis. © 2015 The British Pharmacological Society.

Topics: Animals; Azabicyclo Compounds; Benzoates; Cannabidiol; Cell Adhesion; Cell Line, Tumor; Cell Movement; Colonic Neoplasms; Humans; Liver Neoplasms; Lysophospholipids; Mice; Neoplasm Metastasis; Receptors, Cannabinoid; Receptors, G-Protein-Coupled; RNA, Small Interfering

The novel cannabinoid receptor GPR55 is expressed by rodent islets and it has been implicated in β-cell function in response to a range of ligands. This study evaluated the effects of GPR55 ligands on intracellular calcium ([Ca. GPR55 expression was determined by Western blotting and fluorescent immunohistochemistry. Changes in [Ca. Western blotting indicated that MIN6 β-cells, mouse and human islets express GPR55 and its localization on human β-cells was demonstrated by fluorescent immunohistochemistry. The pharmacological GPR55 agonist O-1602 (10 μM) significantly stimulated [Ca. Our results therefore suggest that GPR55 plays an important role in the regulation of mouse and human islet physiology, but LPI and CBD exert stimulatory effects on islet function by a GPR55-independent pathway(s).

Topics: Animals; Blotting, Western; Calcium; Cannabidiol; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Cell Line; Cyclohexanes; Cytophotometry; Electrophoresis, Polyacrylamide Gel; Humans; Immunohistochemistry; Insulin; Insulin Secretion; Insulin-Secreting Cells; Islets of Langerhans; Lysophospholipids; Mice; Mice, Knockout; Optical Imaging; Receptors, Cannabinoid; Receptors, G-Protein-Coupled; Resorcinols; rhoA GTP-Binding Protein; Single-Cell Analysis

GPR55 is a G protein-coupled receptor recently shown to be activated by certain cannabinoids and by lysophosphatidylinositol (LPI). However, the physiological role of GPR55 remains unknown. Given the recent finding that the cannabinoid receptors CB(1) and CB(2) affect bone metabolism, we examined the role of GPR55 in bone biology. GPR55 was expressed in human and mouse osteoclasts and osteoblasts; expression was higher in human osteoclasts than in macrophage progenitors. Although the GPR55 agonists O-1602 and LPI inhibited mouse osteoclast formation in vitro, these ligands stimulated mouse and human osteoclast polarization and resorption in vitro and caused activation of Rho and ERK1/2. These stimulatory effects on osteoclast function were attenuated in osteoclasts generated from GPR55(-/-) macrophages and by the GPR55 antagonist cannabidiol (CBD). Furthermore, treatment of mice with this non-psychoactive constituent of cannabis significantly reduced bone resorption in vivo. Consistent with the ability of GPR55 to suppress osteoclast formation but stimulate osteoclast function, histomorphometric and microcomputed tomographic analysis of the long bones from male GPR55(-/-) mice revealed increased numbers of morphologically inactive osteoclasts but a significant increase in the volume and thickness of trabecular bone and the presence of unresorbed cartilage. These data reveal a role of GPR55 in bone physiology by regulating osteoclast number and function. In addition, this study also brings to light an effect of both the endogenous ligand, LPI, on osteoclasts and of the cannabis constituent, CBD, on osteoclasts and bone turnover in vivo.

Topics: Animals; Animals, Newborn; Bone and Bones; Bone Density; Bone Resorption; Cannabidiol; Cell Line, Tumor; Cells, Cultured; Dose-Response Relationship, Drug; Female; Fluorescent Antibody Technique; Humans; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Osteoblasts; Osteoclasts; Osteogenesis; Receptors, Cannabinoid; Receptors, G-Protein-Coupled; Reverse Transcriptase Polymerase Chain Reaction