R(+)-methanandamide-induced cyclooxygenase-2 expression in H4 human neuroglioma cells: possible involvement of membrane lipid rafts.
Cannabinoids induce the expression of the cyclooxygenase-2 (COX-2) isoenzyme in H4 human neuroglioma cells via a pathway independent of cannabinoid- or vanilloid receptor activation. The underlying mechanism was recently shown to involve increased synthesis of ceramide, which in turn leads to activation of p38 and p42/44 mitogen-activated protein kinases (MAPKs). The present study investigates a possible contribution of membrane lipid rafts to cannabinoid-induced COX-2 expression. To address this issue, we tested the influence of methyl-beta-cyclodextrin (MCD), a membrane cholesterol depletor, on COX-2 expression by the endocannabinoid analogue R(+)-methanandamide (R(+)-MA). Incubation of H4 cells with MCD was associated with a loss of lipid raft integrity and a substantial inhibition of R(+)-MA-induced COX-2 expression and subsequent formation of prostaglandin E2. Moreover, MCD was shown to suppress signal transduction steps upstream to COX-2 induction by R(+)-MA. Accordingly, the cholesterol depletor suppressed R(+)-MA-induced formation of ceramide as well as phosphorylation of p38 and p42/44 MAPKs. Together, our results suggest that R(+)-MA induces COX-2 expression in human neuroglioma cells via a pathway linked to lipid raft microdomains.
Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich Alexander University Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany. hinz@pharmakologie.uni-erlangen.de
Burkhard
B
Hinz
Robert
R
Ramer
Karin
K
Eichele
Ulrike
U
Weinzierl
Kay
K
Brune
D001095:Arachidonic Acids / Q000494:pharmacology*; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis*; D020935:MAP Kinase Signaling System; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011453:Prostaglandins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D047392:beta-Cyclodextrins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D001095:Arachidonic Acids; D002518:Ceramides; D007527:Isoenzymes; D008565:Membrane Proteins; D011453:Prostaglandins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C088155:methanandamide; C097760:N-palmitoylsphingosine; D002784:Cholesterol; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone