(Endo)cannabinoids mediate different Ca2+ entry mechanisms in human bronchial epithelial cells.
In human bronchial epithelial (16HBE14o(-)) cells, CB(1) and CB(2) cannabinoid receptors are present, and their activation by the endocannabinoid virodhamine and the synthetic non-selective receptor agonist CP55,940 inhibits adenylyl cyclase and cellular interleukin-8 release. Here, we analyzed changes in intracellular calcium ([Ca2+](i)) evoked by Delta(9)-tetrahydrocannabinol (Delta(9)-THC), CP55,940, and virodhamine in 16HBE14o(-) cells. Delta(9)-THC induced [Ca2+](i) increase and a large transient [Ca2+](i) mobilization, the latter probably reflecting store-depletion-driven capacitative Ca2+ entry (CCE). In contrast, CP55,940 induced a rather moderate Ca2+ influx and a sustained [Ca2+](i) mobilization. CP55,940-induced Ca2+ influx was inhibited by Ni2+, indicating CCE, possibly mediated by transient receptor potential channel TRPC1, the mRNA of which is expressed in 16HBE14o(-) cells. CP55,940-induced calcium alterations were mimicked by virodhamine concentrations below 30 microM. Interestingly, higher virodhamine induced an additional Ca2+ entry, insensitive to Ni2+, but sensitive to the TRPV1 antagonist capsazepine, the TRPV1-TRPV4 inhibitor ruthenium red, and the non-CCE (NCCE) inhibitors La3+ and Gd3+. Such pharmacological profile is supported by the presence of TRPV1, TRPV4, and TRPC6 mRNAs as well as TRPV1 and TRPC6 proteins in 16HBE14o(-) cells. Cannabinoid receptor antagonists increased virodhamine-induced Ca2+ entry. Virodhamine also enhanced arachidonic acid release, which was insensitive to cannabinoid receptor antagonism, but sensitive to the phospholipase A(2) inhibitor quinacrine, and to capsazepine. Arachidonic acid induced [Ca2+](i) increase similar to virodhamine. Collectively, these observations suggest that [Ca2+](i) alterations induced by Delta(9)-THC, CP55,940 and by low concentrations of virodhamine involve mobilization and subsequent CCE mechanisms, whereas such responses by high virodhamine concentrations involve NCCE pathways.
Gkoumassi
Effimia
E
Department of Molecular Pharmacology, University Centre for Pharmacy, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands, e.gkoumassi@gmail.com
Dekkers
Bart G J
BG
Dröge
Melloney J
MJ
Elzinga
Carolina R S
CR
Hasenbosch
Rutger E
RE
Meurs
Herman
H
Nelemans
S Adriaan
SA
Schmidt
Martina
M
Zaagsma
Johan
J
D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000008:administration & dosage / Q000494:pharmacology; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D063385:Cannabinoid Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D002186:Cannabinoids / Q000008:administration & dosage / Q000494:pharmacology*; D002460:Cell Line; D003511:Cyclohexanols / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D050052:TRPC Cation Channels / Q000378:metabolism
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D003511:Cyclohexanols; D012333:RNA, Messenger; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; C456739:virodhamine; D016718:Arachidonic Acid; D013759:Dronabinol; C054649:3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol; D002118:Calcium