title: Opposing actions of endocannabinoids on cholangiocarcinoma growth: recruitment of Fas and Fas ligand to lipid rafts.
abstract: Cholangiocarcinomas are devastating cancers of biliary origin with limited treatment options. Modulation of the endocannabinoid system is being targeted to develop possible therapeutic strategies for a number of cancers; therefore, we evaluated the effects of the two major endocannabinoids, anandamide and 2-arachidonylglycerol, on numerous cholangiocarcinoma cell lines. Although anandamide was antiproliferative and proapoptotic, 2-arachidonylglycerol stimulated cholangiocarcinoma cell growth. Specific inhibitors for each of the cannabinoid receptors did not prevent either of these effects nor did pretreatment with pertussis toxin, a G(i/o) protein inhibitor, suggesting that anandamide and 2-arachidonylglycerol did not exert their diametric effects through any known cannabinoid receptor or through any other G(i/o) protein-coupled receptor. Using the lipid raft disruptors methyl-beta-cyclodextrin and filipin, we demonstrated that anandamide, but not 2-arachidonylglycerol, requires lipid raft-mediated events to inhibit cellular proliferation. Closer inspection of the lipid raft structures within the cell membrane revealed that although anandamide treatment had no observable effect 2-arachidonylglycerol treatment effectively dissipated the lipid raft structures and caused the lipid raft-associated proteins lyn and flotillin-1 to disperse into the surrounding membrane. In addition, anandamide, but not 2-arachidonylglycerol, induced an accumulation of ceramide, which was required for anandamide-induced suppression of cell growth. Finally we demonstrated that anandamide and ceramide treatment of cholangiocarcinoma cells recruited Fas and Fas ligand into the lipid rafts, subsequently activating death receptor pathways. These findings suggest that modulation of the endocannabinoid system may be a target for the development of possible therapeutic strategies for the treatment of this devastating cancer.
authors.affiliation: Division of Research and Education, Scott and White Hospital and Texas A&M University System Health Science Center College of Medicine, Temple, Texas 76504, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: DeMorrow
authors.forename: Shannon
authors.initials: S
authors.lastname: Glaser
authors.forename: Heather
authors.initials: H
authors.lastname: Francis
authors.forename: Julie
authors.initials: J
authors.lastname: Venter
authors.forename: Bradley
authors.initials: B
authors.lastname: Vaculin
authors.forename: Shelley
authors.initials: S
authors.lastname: Vaculin
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Alpini
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001095:Arachidonic Acids / Q000494:pharmacology* / Q000627:therapeutic use; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018281:Cholangiocarcinoma / Q000188:drug therapy / Q000378:metabolism*; D004354:Drug Screening Assays, Antitumor; D063388:Endocannabinoids; D053222:Fas Ligand Protein / Q000378:metabolism*; D005372:Filipin / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D005989:Glycerides / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology* / Q000627:therapeutic use; D047392:beta-Cyclodextrins / Q000494:pharmacology; D019014:fas Receptor / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D053222:Fas Ligand Protein; D005989:Glycerides; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D053284:Polyunsaturated Alkamides; D047392:beta-Cyclodextrins; D019014:fas Receptor; C106354:flotillins; C108732:methyl-beta-cyclodextrin; D005372:Filipin; C094503:glyceryl 2-arachidonate; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C078814:anandamide