title: Δ-Tetrahydrocannabinol induces cytotoxicity in macrophage J774-1 cells: involvement of cannabinoid receptor 2 and p38 MAPK.
abstract: Tetrahydrocannabinol (THC), a psychoactive component of marijuana, is known to exert cytotoxicity in immune cells. In the present study, we examined the cytotoxicity of Δ⁸-THC in mouse macrophage J774-1 cells and a possible involvement of cannabinoid receptors and stress-responsive mitogen-activated protein kinases (MAPKs) in the cytotoxic process. J774-1 cells were treated with Δ⁸-THC (0-20 μM) for up to 6 h. As measured by the MTT and LDH assays, Δ⁸-THC induced cell death of J774-1 cells in a concentration- and/or exposure time-dependent manner. Δ⁸-THC-induced cell damage was associated with vacuole formation, cell swelling, chromatin condensation, and nuclear fragmentation. The cytotoxic effect of Δ⁸-THC was significantly prevented by a caspase-1 inhibitor Ac-YVAD-cmk but not a caspase-3 inhibitor z-DEVD-fmk. The pretreatment with SR144528, a CB₂ receptor-selective antagonist, effectively suppressed Δ⁸-THC-induced cytotoxicity in J774-1 cells, which exclusively expressed CB₂ receptors as indicated by real-time polymerase chain reaction analysis. In contrast, AM251, a CB₁ receptor-selective antagonist, did not affect the cytotoxicity. Pertussis toxin and α-tocopherol significantly attenuated Δ⁸-THC-induced cytotoxicity suggesting that G(i/o) protein coupling signal transduction and oxidative stress are responsible for the cytotoxicity. Δ⁸-THC stimulated the phosphorylation of p38 MAPK and c-Jun N-terminal kinase (JNK) in J774-1 cells, which were effectively antagonized by the pretreatment with SR144528. In addition, SB203580, a p38 MARK inhibitor, significantly attenuated the cytotoxic effect of Δ⁸-THC, whereas SP600125, a JNK inhibitor, significantly enhanced the cytotoxicity. These results suggest that the cytotoxicity of Δ⁸-THC to J774-1 cells is exerted mediated through the CB₂ receptor followed by the activation of p38 MAPK.
authors.affiliation: Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3, Kanagawa-machi, Kanazawa 920-1181, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaori
authors.forename: Hirosuke
authors.initials: H
authors.lastname: Ishii
authors.forename: Kenzo
authors.initials: K
authors.lastname: Chiba
authors.forename: Ikuo
authors.initials: I
authors.lastname: Yamamoto
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D011725:Pyridines / Q000494:pharmacology; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D043885:Receptor, Cannabinoid, CB2; D013759:Dronabinol; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580
keywords: 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide; CB(2) receptor; Cytotoxicity; DMSO; JNK; LDH; MAPK; MTT; Macrophage; PBS; PCR; ROS; THC; Tetrahydrocannabinol; c-Jun N-terminal kinase; dimethyl sulfoxide; lactate dehydrogenase; mitogen-activated protein kinase; p38 MAPK; phosphate-buffered saline; polymerase chain reaction; reactive oxygen species; tetrahydrocannabinol