The involvement of VEGF receptors and MAPK in the cannabinoid potentiation of Ca2+ flux into N18TG2 neuroblastoma cells.
In addition to their inhibitory effects, cannabinoids also exert stimulatory activity which can be detected at the cellular level. In a previous study, we demonstrated a stimulatory effect of the synthetic cannabinoid receptor agonist desacetyllevonantradol (DALN) on Ca(2+) flux into N18TG2 neuroblastoma cells, and suggested a dual mechanism: one pathway mediated by PKA and the other one by protein kinase C (PKC). Here we studied the PKC-mediated effect of DALN on Ca(2+) influx. The stimulatory effect of DALN on Ca(2+) influx was partially blocked by the PKC inhibitor chelerythrine, by the metalloprotease inhibitor o-phenanthroline and by the MEK (mitogen-activated protein-kinase kinase, MAPK kinase) inhibitor PD98059. Immunobloting of ERK1/2 MAPK demonstrated phosphorylation by DALN, and indicated the involvement of vascular endothelial growth factor (VEGF) receptor tyrosin kinases (RTKs) in MAPK activation as it was blocked by oxindole-1. Transactivation of the VEGFR-MAPK cascade by DALN involved CB1 cannabinoid receptors coupled to Gi/Go GTP-binding proteins as it was blocked by SR141716A and by pertussis toxin (PTX). The pharmacological implications of this novel mechanism of cannabinoid activity are discussed.
Rubovitch
Vardit
V
The Mauerberger Chair in Neuropharmacology, Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 69978, Israel. sarney@post.tau.ac.il
Gafni
Mikhal
M
Sarne
Yosef
Y
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D063387:Cannabinoid Receptor Antagonists; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009447:Neuroblastoma; D037342:Pertussis Toxin / Q000494:pharmacology; D010617:Phenanthridines / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D063387:Cannabinoid Receptor Antagonists; D004791:Enzyme Inhibitors; D010617:Phenanthridines; C032426:desacetylnantradol; D037342:Pertussis Toxin; D040262:Receptors, Vascular Endothelial Growth Factor; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium