2-Arachidonoylglycerol Induces the Migration of HL-60 Cells Differentiated into Macrophage-like Cells and Human Peripheral Blood Monocytes through the Cannabinoid CB2 Receptor-dependent Mechanism

Abstract

2-Arachidonoylglycerol is an endogenous ligand for the cannabinoid receptors (CB1 and CB2) and has been shown to exhibit a variety of cannabimimetic activities in vitro and in vivo. Recently, we proposed that 2-arachidonoylglycerol is the true endogenous ligand for the cannabinoid receptors, and both receptors (CB1 and CB2) are primarily 2-arachidonoylglycerol receptors. The CB1 receptor is assumed to be involved in the attenuation of neurotransmission. On the other hand, the physiological roles of the CB2 receptor, which is abundantly expressed in several types of leukocytes such as macrophages, still remain unknown. In this study, we examined the effects of 2-arachidonoylglycerol on the motility of HL-60 cells differentiated into macrophage-like cells. We found that 2-arachidonoylglycerol induces the migration of differentiated HL-60 cells. The migration induced by 2-arachidonoylglycerol was blocked by treatment of the cells with either SR144528, a CB2 receptor antagonist, or pertussis toxin, suggesting that the CB2 receptor and Gi/Go are involved in the 2-arachidonoylglycerol-induced migration. Several intracellular signaling molecules such as Rho kinase and mitogen-activated protein kinases were also suggested to be involved. In contrast to 2-arachidonoylglycerol, anandamide, another endogenous cannabinoid receptor ligand, failed to induce the migration. The 2-arachidonoylglycerol-induced migration was also observed for two other types of macrophage-like cells, the U937 cells and THP-1 cells, as well as human peripheral blood monocytes. These results strongly suggest that 2-arachidonoylglycerol induces the migration of several types of leukocytes such as macrophages/monocytes through a CB2 receptor-dependent mechanism thereby stimulating inflammatory reactions and immune responses. 2-Arachidonoylglycerol is an endogenous ligand for the cannabinoid receptors (CB1 and CB2) and has been shown to exhibit a variety of cannabimimetic activities in vitro and in vivo. Recently, we proposed that 2-arachidonoylglycerol is the true endogenous ligand for the cannabinoid receptors, and both receptors (CB1 and CB2) are primarily 2-arachidonoylglycerol receptors. The CB1 receptor is assumed to be involved in the attenuation of neurotransmission. On the other hand, the physiological roles of the CB2 receptor, which is abundantly expressed in several types of leukocytes such as macrophages, still remain unknown. In this study, we examined the effects of 2-arachidonoylglycerol on the motility of HL-60 cells differentiated into macrophage-like cells. We found that 2-arachidonoylglycerol induces the migration of differentiated HL-60 cells. The migration induced by 2-arachidonoylglycerol was blocked by treatment of the cells with either SR144528, a CB2 receptor antagonist, or pertussis toxin, suggesting that the CB2 receptor and Gi/Go are involved in the 2-arachidonoylglycerol-induced migration. Several intracellular signaling molecules such as Rho kinase and mitogen-activated protein kinases were also suggested to be involved. In contrast to 2-arachidonoylglycerol, anandamide, another endogenous cannabinoid receptor ligand, failed to induce the migration. The 2-arachidonoylglycerol-induced migration was also observed for two other types of macrophage-like cells, the U937 cells and THP-1 cells, as well as human peripheral blood monocytes. These results strongly suggest that 2-arachidonoylglycerol induces the migration of several types of leukocytes such as macrophages/monocytes through a CB2 receptor-dependent mechanism thereby stimulating inflammatory reactions and immune responses. Δ9-Tetrahydrocannabinol (Δ9-THC) 1The abbreviations used are: Δ9-THC, Δ9-tetrahydrocannabinol; 2-AG, 2-arachidonoylglycerol; NBT, nitroblue tetrazolium; PTX, pertussis toxin; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; MAP, mitogen-activated protein; MEK, MAP kinase/extracellular signal-regulated kinase kinase. 1The abbreviations used are: Δ9-THC, Δ9-tetrahydrocannabinol; 2-AG, 2-arachidonoylglycerol; NBT, nitroblue tetrazolium; PTX, pertussis toxin; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; MAP, mitogen-activated protein; MEK, MAP kinase/extracellular signal-regulated kinase kinase. is a major psychoactive constituent of marijuana and is known to exert a variety of biological effects in experimental animals and human such as altered perception, inhibition of memory, immobility, analgesia, and the inhibition of immune response, although the mechanism of these actions of Δ9-THC remained elusive until the late 1980's. In 1988, Devane et al. (1Devane W.A. Dysarz III, F.A. Johnson M.R. Melvin L.S. Howlett A.C. Mol. Pharmacol. 1998; 34: 605-613Google Scholar) demonstrated the presence of a specific binding site for cannabinoids in rat brain synaptosomes. Later, Matsuda et al. (2Matsuda L.A. Lolait S.J. Brownstein M.J. Young A.C. Bonner T.I. Nature. 1990; 346: 561-564Google Scholar) and Munro et al. (3Munro S. Thomas K.L. Abu-Shaar M. Nature. 1993; 365: 61-65Google Scholar) cloned the cDNAs for the cannabinoid receptors (CB1 and CB2). It has been assumed that the diverse actions of the cannabinoids are mediated in a large part through these receptors. In 1992, Devane et al. (4Devane W.A. Hanus L. Breuer A. Pertwee R.G. Stevenson L.A. Griffin G. Gibson D. Mandelbaum A. Etinger A. Mechoulam R. Science. 1992; 258: 1946-1949Google Scholar) isolated N-arachidonoylethanolamine (anandamide) from pig brain as an endogenous cannabinoid receptor ligand. This compound has been shown to exhibit various cannabimimetic activities in vitro and in vivo (5Di Marzo V. Biochim. Biophys. Acta. 1998; 1392: 153-175Google Scholar, 6Piomelli D. Beltramo M. Giuffrida A. Stella N. Neurobiol. Dis. 1998; 5: 462-473Google Scholar, 7Mechoulam R. Fride E. Di Marzo V. Eur. J. Pharmacol. 1998; 359: 1-18Google Scholar, 8Di Marzo V. De Petrocellis L. Bisogno T. Berger A. Mechoulam R. Onaivi E.S. Biology of Marijuana. Taylor & Francis, London2002: 125-174Google Scholar). However, the levels of anandamide in various living tissues were very low (9Hansen H.S. Moesgaard B. Hansen H.H. Petersen G. Chem. Phys. Lipids. 2000; 108: 135-150Google Scholar, 10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar). Furthermore, anandamide was found to act as a partial agonist at the cannabinoid receptors (10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar). These observations strongly suggested the existence of another endogenous ligand in mammalian tissues. In 1995, we (11Sugiura T. Kondo S. Sukagawa A. Nakane S. Shinoda A. Itoh K. Yamashita A. Waku K. Biochem. Biophys. Res. Commun. 1995; 215: 89-97Google Scholar) and Mechoulam et al. (12Mechoulam R. Ben-Shabat S. Hanus L. Ligumsky M. Kaminski N.E. Schatz A.R. Gopher A. Almog S. Martin B.R. Compton D.R. Pertwee R.G. Griffin G. Bayewitch M. Barg J. Vogel Z. Biochem. Pharmacol. 1995; 50: 83-90Google Scholar) reported that 2-arachidonoylglycerol (2-AG) is the second endogenous ligand for the cannabinoid receptors. 2-AG has been shown to exhibit a strong binding activity toward the cannabinoid receptors (11Sugiura T. Kondo S. Sukagawa A. Nakane S. Shinoda A. Itoh K. Yamashita A. Waku K. Biochem. Biophys. Res. Commun. 1995; 215: 89-97Google Scholar, 12Mechoulam R. Ben-Shabat S. Hanus L. Ligumsky M. Kaminski N.E. Schatz A.R. Gopher A. Almog S. Martin B.R. Compton D.R. Pertwee R.G. Griffin G. Bayewitch M. Barg J. Vogel Z. Biochem. Pharmacol. 1995; 50: 83-90Google Scholar) and a variety of cannabimimetic activities (5Di Marzo V. Biochim. Biophys. Acta. 1998; 1392: 153-175Google Scholar, 6Piomelli D. Beltramo M. Giuffrida A. Stella N. Neurobiol. Dis. 1998; 5: 462-473Google Scholar, 7Mechoulam R. Fride E. Di Marzo V. Eur. J. Pharmacol. 1998; 359: 1-18Google Scholar, 8Di Marzo V. De Petrocellis L. Bisogno T. Berger A. Mechoulam R. Onaivi E.S. Biology of Marijuana. Taylor & Francis, London2002: 125-174Google Scholar, 10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar, 13Sugiura T. Waku K. Chem. Phys. Lipids. 2000; 108: 89-106Google Scholar, 14Sugiura T. Waku K. J. Biochem. 2002; 132: 7-12Google Scholar). Importantly, 2-AG was found to act as a full agonist at the cannabinoid receptors (15Sugiura T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google Scholar, 16Sugiura T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar, 17Hillard C.J. Prostaglandins Lipid Mediators. 2000; 61: 3-18Google Scholar, 18Gonsiorek W. Lunn C. Fan X. Narula S. Lundell D. Hipkin R.W. Mol. Pharmacol. 2000; 57: 1045-1050Google Scholar, 19Savinainen J.R. Jarvinen T. Laine K. Laitinen J.T. Br. J. Pharmacol. 2001; 134: 664-672Google Scholar). Moreover, 2-AG can be rapidly formed from arachidonic acid-containing phospholipids, such as inositol phospholipids, through the combined actions of phospholipase C and diacylglycerol lipase or the combined actions of phospholipase A1 and phospholipase C in various types of tissues and cells upon stimulation (20Bisogno T. Sepe N. Melck D. Maurelli S. De Petrocellis L. Di Marzo V. Biochem. J. 1997; 322: 671-677Google Scholar, 21Stella N. Schweitzer P. Piomelli D. Nature. 1997; 388: 773-778Google Scholar, 22Sugiura T. Kodaka T. Nakane S. Kishimoto S. Kondo S. Waku K. Biochem. Biophys. Res. Commun. 1998; 243: 838-843Google Scholar, 23Varga K. Wagner J.A. Bridgen D.T. Kunos G. FASEB J. 1998; 12: 1035-1044Google Scholar, 24Di Marzo V. Bisogno T. De Petrocellis L. Melck D. Orlando P. Wagner J.A. Kunos G. Eur. J. Biochem. 1999; 264: 258-267Google Scholar, 25Berdyshev E.V. Schmid P.C. Krebsbach R.J. Schmid H.H.O. FASEB J. 2001; 15: 2171-2178Google Scholar, 26Basavarajappa B.S. Saito M. Cooper T.B. Hungund B.L. Biochim. Biophys. Acta. 2000; 1535: 78-86Google Scholar). Noticeably, the levels of 2-AG in various mammalian tissues are markedly higher than that of anandamide. Based on these results, we proposed that 2-AG, and not anandamide, is the intrinsic natural ligand for the cannabinoid receptors (15Sugiura T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google Scholar, 16Sugiura T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar, 27Sugiura T. Kodaka T. Kondo S. Nakane S. Kondo H. Waku K. Ishima Y. Watanabe K. Yamamoto I. J. Biochem. 1997; 122: 890-895Google Scholar). Despite their potential physiological and pathophysiological importance, the exact functions of the CB1 and CB2 receptors and their endogenous ligand 2-AG have not yet been fully elucidated. As for the CB1 receptor, several lines of evidence strongly suggested that 2-AG suppresses the neurotransmission through acting at the CB1 receptor expressed predominantly in the presynapse (10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar, 13Sugiura T. Waku K. Chem. Phys. Lipids. 2000; 108: 89-106Google Scholar, 14Sugiura T. Waku K. J. Biochem. 2002; 132: 7-12Google Scholar). It is becoming evident that 2-AG is a novel type of neuromodulator of profound physiological significance. On the other hand, the functions of the CB2 receptor, which is abundantly expressed in the immune system, still remain an enigma. Little is known concerning the biological activities of 2-AG toward inflammatory cells and immune competent cells. It is to in the functions of the CB2 receptor and 2-AG to the of inflammatory reactions and immune responses. In this study, we the biological activity of 2-AG toward HL-60 cells differentiated into macrophage-like cells. We found that 2-AG induces the migration of differentiated HL-60 cells through a cannabinoid CB2 receptor-dependent was also observed with human monocytes. The physiological and pathophysiological of the migration of macrophages/monocytes are and were from and were from was from was from and were from was from and were from was from was a from was as in T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google 2-AG and the other were from and as (15Sugiura T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google Scholar). of 2-AG was from and as (15Sugiura T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google Scholar). HL-60 cells, human U937 cells, and THP-1 cells were at in with in an of and HL-60 cells were differentiated into macrophage-like cells by treatment with for U937 cells and THP-1 cells were also differentiated by treatment with for were from the peripheral blood of as of in was to blood to the the was and at for the cells were with and the cells were and at for The was and with were from other leukocytes by a The of the was as by a migration of the differentiated HL-60 cells, U937 cells, THP-1 cells, and human was and the cells for the differentiated HL-60 cells, U937 cells, and THP-1 cells and for human in of were to the 2-AG was in and to of the in the well of the of was the at for HL-60 cells, U937 cells, and THP-1 cells and for human in an of and the of cells that from the to the was a was as S.J. J. Scholar) with were in and at for was to the at a of and the was for at the of to the the of cells was a activity was an from and differentiated HL-60 cells were in a and a The CB2 CB2 receptor and glyceraldehyde-3-phosphate were with the was at for in The was in and at and by a of the of 2-AG the with the cells differentiated into macrophage-like cells were in of The cells were with 2-AG for and the the was and the were by the of and J. Biochem. Scholar). was to and was as an The were by with in a with The to was the by from the by the of and J. Biochem. Scholar). The was in the presence of in an The were to their and with a with a and a at at The was and the was as S. Kondo H. Nakane S. Kodaka T. A. Waku K. T. 1998; Scholar). was the is known to induce the of HL-60 cells into macrophage-like cells R. A. J. Scholar). We examined the of on several of and the CB2 receptor in HL-60 cells. As shown in the of cells in HL-60 cells was low On the other hand, the of cells was to the with was observed for cells not We examined differentiated HL-60 cells the CB2 receptor As shown in differentiated HL-60 cells were found to a of the CB2 receptor The of the CB2 receptor in the differentiated HL-60 cells was the as that in the HL-60 cells of the CB2 receptor in the differentiated cells was of that in the We the of 2-AG on the motility of HL-60 cells. The of 2-AG the migration of HL-60 cells to although the of cells was the of the cells were and for the and cells, On the other hand, 2-AG effects on the migration of the HL-60 cells differentiated into macrophage-like cells by treatment with for The of cells was for the and for the cells. The of HL-60 cells differentiated into macrophage-like cells was with The of 2-AG markedly the migration The of cells also The was observed from 2-AG and a at The was We examined the cannabinoid receptors are involved in the migration of differentiated HL-60 cells. We found that the of SR144528, a cannabinoid CB2 antagonist, to the cells markedly the migration induced by 2-AG On the other hand, the treatment of the cells with a cannabinoid CB1 antagonist, a on the migration. These results that the migration is mediated the CB2 The of treatment on the migration of the differentiated HL-60 cells was As shown in of the cells with the migration by 2-AG, that Gi/Go is involved in the migration. We examined the effects of various of intracellular signaling on migration. As shown in MAP kinase/extracellular signal-regulated kinase kinase MAP kinase and Rho kinase the migration of differentiated HL-60 cells induced by On the other hand, and kinase not the migration We also that not the migration at not of various on migration of HL-60 cells differentiated into macrophage-like cells by treatment with HL-60 cells differentiated into macrophage-like cells were with various at for and to the was to the 2-AG was to the The migration of the cells from the to the was examined as The are the of with the We the activities of the various cannabinoid receptor to induce migration. As shown in the activity of 2-AG was the of the various cannabinoid receptor examined in the 2-AG a of 2-AG, although activity was than that of and were also found to However, anandamide was The activities of the various of the to induce migration were The activity was observed with 2-AG activities were also observed with and However, the activities of the other such as and were We examined the migration is of a or in specific The migration of the cells from the to the in the of 2-AG was The of cells was to 2-AG was to the The migration was 2-AG was to both the and the On the other hand, the presence of 2-AG in the not migration 2-AG is known to be rapidly by a variety of cells (10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar, 13Sugiura T. Waku K. Chem. Phys. Lipids. 2000; 108: 89-106Google we examined 2-AG as an the with the cells. We found that than of the 2-AG was of is to the migration is of or the experimental 2-AG as a this we 2-AG a of 2-AG, of 2-AG We found that the of cells 2-AG was to both the and the was than that observed 2-AG was to the the of cells in the to the of the We also found that the of 2-AG to the not the migration of cells from the to the These results strongly suggest that 2-AG than We 2-AG induces the migration of other types of macrophage-like cells. In this study, we two types of human cells, U937 cells and THP-1 cells, which were differentiated by treatment with as in the of the HL-60 cells. We found that 2-AG the migration of the differentiated U937 cells and THP-1 cells although the of was with the of the differentiated HL-60 cells. we examined human peripheral blood to As shown in 2-AG markedly the migration of human monocytes. The of 2-AG was by treatment of the cells with a CB2 antagonist, as in the of differentiated HL-60 cells. The cannabinoid CB2 receptor is a receptor and is expressed abundantly in various types of inflammatory cells and immune competent cells such as macrophages, natural cells, and E.V. Chem. Phys. Lipids. 2000; 108: Scholar, D. P. T. E. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: Scholar, Onaivi E.S. Biology of Marijuana. Taylor & Francis, London2002: Scholar). T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google we examined in the of a of CB2 receptor HL-60 cells, which the CB2 receptor and exhibit a with the CB2 receptor We found that the of 2-AG is by the CB2 receptor T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar). The activity of 2-AG was various Noticeably, 2-AG as a full agonist at the CB2 receptor anandamide as a partial et al. W. Lunn C. Fan X. Narula S. Lundell D. Hipkin R.W. Mol. Pharmacol. 2000; 57: 1045-1050Google Scholar) also demonstrated that 2-AG is a full and anandamide is a partial agonist the of cells with the human CB2 receptor We proposed that 2-AG, not anandamide, is the intrinsic natural ligand for the cannabinoid CB2 receptor, and the CB2 receptor is primarily a 2-AG receptor T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar). is concerning the biological activities of 2-AG toward inflammatory cells and immune competent cells. Kaminski and M. Kaminski N.E. J. Pharmacol. 1995; 275: Scholar) reported that 2-AG also demonstrated that 2-AG suppresses the in through of the Y. Kaminski N.E. Mol. Pharmacol. 1998; Scholar). In et al. J. Biochem. 2001; Scholar) demonstrated that 2-AG the of in macrophage-like cells. It these effects of 2-AG are mediated through the cannabinoid Recently, we found that 2-AG induces and of the MAP kinase in HL-60 cells Y. S. Waku K. T. J. Biochem. 2001; Scholar). of the MAP kinase was the cells were with either or PTX, that the was mediated through the CB2 receptor and We also found that of the MAP kinase and kinase in HL-60 cells. and Y. The of the MAP kinase and kinase has also been reported by several P. C. M. J.A. J. 2001; Scholar, D. I. A. M. Mol. Pharmacol. 2000; Scholar). These results strongly suggest that 2-AG in the and immune although the exact physiological functions of 2-AG in inflammatory cells and immune competent cells still remain In this study, we the of 2-AG on the motility of HL-60 cells. We found that 2-AG induces the migration of HL-60 cells differentiated into macrophage-like cells effects were observed with other macrophage-like cells of human such as U937 cells and THP-1 cells and human peripheral blood and suggesting that migration is a in human The migration of differentiated HL-60 cells was markedly the cells were with either or suggesting that the migration was mediated through the CB2 receptor and and not in the arachidonic was not of the migration not This was also by the that 2-AG was to induce the migration although activity was with that of On the other hand, the Rho and MAP were suggested to be involved in the migration of differentiated HL-60 cells, Rho kinase and MAP kinase the migration The inhibition of migration by T. R. S. S. R. H. J. J. 2001; Scholar, N. H. M. T. J. Biol. Chem. 2001; S. T. T. S. J.A. R. 2000; Scholar, M.J. Eur. J. 2002; Scholar, M. P. J. 1999; and N. H. M. T. J. Biol. Chem. 2001; Scholar, J. Biol. Chem. 1999; 274: Scholar) has been reported for several types of cells with various although are results as to the inhibition by N. H. M. T. J. Biol. Chem. 2001; Scholar, J. Biol. Chem. 1999; 274: Scholar). The Rho kinase and MAP as well as MEK, is known to be et al. N. H. M. T. J. Biol. Chem. 2001; Scholar) reported that Rho kinase is of MAP kinase in THP-1 cells. of the intracellular signaling for migration of HL-60 cells be in the The activity of 2-AG was of the various cannabinoid receptor This is in of the that 2-AG is the true endogenous ligand of the cannabinoid CB2 It has been shown that 2-AG is in in various mammalian tissues (10Sugiura T. Kobayashi Y. Oka S. Waku K. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: 173-192Google Scholar, 13Sugiura T. Waku K. Chem. Phys. Lipids. 2000; 108: 89-106Google Scholar). and not exhibit and induced the migration to These results are in with the results of the reported T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar). We have found that the presence of the at the is for of the molecules (15Sugiura T. Kodaka T. Nakane S. Miyashita T. Kondo S. Suhara Y. Takayama H. Waku K. Seki C. Baba N. Ishima Y. J. Biol. Chem. 1999; 274: 2794-2801Google Scholar, 16Sugiura T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar). The migration of HL-60 cells induced by 2-AG was assumed to than 2-AG This was also by the that the migration of HL-60 cells observed in the presence of 2-AG in both the and was markedly with the of the presence of 2-AG in the a lipase was to the of and for 2-AG in the and 2-AG in both of M. and T. We that 2-AG was rapidly the with the cells the lipase was not in the as It be that part of the migration induced by 2-AG was of the and the mechanism of the that 2-AG induces the migration of macrophage-like cells and is various types of molecules are known to induce the migration and of inflammatory cells. et al. V. M. A. B. R. 2002; Scholar) also demonstrated that 2-AG induces the migration of and cells, yet the of the mechanism of migration of these cells et al. R. Breuer A. Mechoulam R. Eur. J. Pharmacol. 2000; Scholar) reported that 2-AG suppresses the of in in vitro and in in although these effects of 2-AG are mediated through the CB2 receptor is On the other hand, we found that the of 2-AG to HL-60 cells the of such as and through a CB2 and Kishimoto and T. Based on the results of a on and the on we that 2-AG as a or than as a of reactions and immune responses. As for Δ9-THC, has been reported that Δ9-THC suppresses and immune in vivo E.V. Chem. Phys. Lipids. 2000; 108: Scholar, D. P. T. E. Prostaglandins Leukotrienes Essent. Fatty Acids. 2002; 66: Scholar, Onaivi E.S. Biology of Marijuana. Taylor & Francis, London2002: Scholar). The mechanism by which Δ9-THC suppresses the inflammatory reactions and immune has remained we demonstrated that Δ9-THC is a partial agonist of the cannabinoid CB2 receptor T. Kondo S. Kishimoto S. Miyashita T. Nakane S. Kodaka T. Suhara Y. Takayama H. Waku K. J. Biol. Chem. 2000; 275: 605-612Google Scholar). Bayewitch et al. M. T. Breuer A. Mechoulam R. J. Biol. Chem. Scholar) also reported that Δ9-THC as an toward the CB2 Noticeably, and CB2 receptor in vivo H. H. Y. T. T. J. Pharmacol. 2001; Scholar). It is that Δ9-THC the of the endogenous natural ligand of the CB2 receptor, that 2-AG, thereby the of inflammatory reactions and immune responses. In we found that 2-AG induces the migration of HL-60 cells differentiated into macrophage-like cells through the CB2 and several other signaling effects were observed with other macrophage-like cells and human monocytes. The migration induced by 2-AG was to than 2-AG is known to be from inflammatory cells and immune competent cells such as upon stimulation (20Bisogno T. Sepe N. Melck D. Maurelli S. De Petrocellis L. Di Marzo V. Biochem. J. 1997; 322: 671-677Google Scholar, 23Varga K. Wagner J.A. Bridgen D.T. Kunos G. FASEB J. 1998; 12: 1035-1044Google Scholar, 24Di Marzo V. Bisogno T. De Petrocellis L. Melck D. Orlando P. Wagner J.A. Kunos G. Eur. J. Biochem. 1999; 264: 258-267Google Scholar, 25Berdyshev E.V. Schmid P.C. Krebsbach R.J. Schmid H.H.O. FASEB J. 2001; 15: 2171-2178Google Scholar) through an such as inositol It is that 2-AG, from a variety of tissues and cells, and roles the of inflammatory reactions and immune responses.