2-Arachidonoylglycerol stimulates activator protein-1-dependent transcriptional activity and enhances epidermal growth factor-induced cell transformation in JB6 P+ cells.
2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid, and it plays a critical role in cannabinoid receptor-mediated cell signaling. Although 2-AG was shown to induce ERK activation via the cannabinoid receptor 1 (CB1), only a nonspecific CB receptor agonist and antagonist was used in those studies. Whether cannabinoid receptor 2 (CB2) is involved in 2-AG-induced ERK activation is still unclear. Moreover, whether 2-AG is involved in mediation of AP-1 activity and cell transformation is also not known. In the present study, we show that 2-AG stimulates AP-1-dependent transcriptional activity and enhances epidermal growth factor-induced cell transformation in mouse epidermal JB6 P+ Cl41 cells. Using JB6 P+ C141 cells, stably transfected with an AP-1 luciferase reporter, we found that 10 microm 2-AG induced up to a 3-fold stimulation of AP-1 transcriptional activity. The AP-1 stimulation appeared to be mediated by ERK but not JNK or p38 kinase. PD98059, a specific inhibitor of MEK1, almost completely blocked 2-AG-induced ERK phosphorylation and AP-1 activation. Using CB1/2-/- murine embryonic fibroblasts, we present the first direct evidence that both cannabinoid receptors 1 and 2 (CB1/2) are involved in 2-AG-induced ERK activation. 2-AG could not stimulate ERK phosphorylation or Fyn kinase activity in dominant negative Fyn. In addition, the Fyn inhibitor PP2 blocked 2-AG-induced Fyn kinase activity and ERK phosphorylation and activity. Small interfering RNA Fyn also suppressed 2-AG-induced ERK phosphorylation. Interestingly, 2-AG enhanced epidermal growth factor-induced AP-1 DNA binding and cell transformation. Taken together, our data provide direct evidence suggesting that 2-AG may have a novel role in cell transformation and carcinogenesis in a signaling pathway involving CB1/2 and activation of Fyn, ERKs, and AP-1.
Zhao
Qing
Q
Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA.
He
Zhiwei
Z
Chen
Nanyue
N
Cho
Yong-Yeon
YY
Zhu
Feng
F
Lu
Chengrong
C
Ma
Wei-Ya
WY
Bode
Ann M
AM
Dong
Zigang
Z
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D004357:Drug Synergism; D063388:Endocannabinoids; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005989:Glycerides / Q000494:pharmacology*; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D043884:Receptor, Cannabinoid, CB1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000187:drug effects*; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism
D001095:Arachidonic Acids; D063388:Endocannabinoids; D005989:Glycerides; D011518:Proto-Oncogene Proteins; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D018808:Transcription Factor AP-1; D004815:Epidermal Growth Factor; C094503:glyceryl 2-arachidonate; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases