Abstract

Recent studies have suggested that cell migratory responses are often mediated by G_i protein-coupled receptors. Because it is known that CB1 cannabinoid receptors are coupled to pertussis toxin-sensitive G proteins, we proposed that CB1 may mediate cell migration. To test this hypothesis, modified Boyden chamber assays were used to investigate cell migration mediated by CB1 cannabinoid receptors. HU-210, WIN55212-2, and anandamide, three cannabinoid agonists with distinct chemical structures, induced migration of human embryonic kidney 293 cells stably transfected with humanCB1 gene, but not 293 cells transfected with an empty expression vector. These migratory responses were concentration-dependent. The EC₅₀ values for HU-210, WIN55212-2, and anandamide were 0.19 ± 0.04, 12.2 ± 1.4, and 39.9 ± 3.7 nM, respectively. The maximal migration index for HU-210, WIN55212-2, and anandamide were 8.9 ± 1.6, 9.5 ± 1.6, and 8.8 ± 1.3, respectively. Pretreating cells with 100 ng/ml pertussis toxin eliminated the cannabinoid agonist-induced cell migration. SR141716A, a selective antagonist for CB1, inhibited the cannabinoid agonist-induced migratory responses in a concentration-dependent manner. Checkerboard analysis demonstrated that anandamide-induced cell migrations are due to chemotaxis as well as chemokinesis. Furthermore, anandamide-induced migratory responses were inhibited, in a concentration-dependent manner, by PD098059, an inhibitor of mitogen-activated protein kinase activation, but not by 8-bromoadenosine-3′,5′-cyclic monophosphate, a cell-permeable cAMP analog. These data demonstrate that cannabinoid agonists are able to induce chemotaxis and chemokinesis, and that these migratory responses are mediated by G protein-coupled, CB1 cannabinoid receptors. In addition, these data suggest that activation of mitogen-activated protein kinase plays an important role, whereas inhibition of adenylate cyclase is probably not involved in the cell migration mediated by CB1.