Antagonistic effect of YM022, an antiulcer agent in rats, on human cholecystokinin (CCK)B/gastrin receptor.
We recently isolated a cDNA clone for the human cholecystokinin (CCK)B/gastrin receptor and permanently expressed this receptor cDNA in NIH-3T3 cells. [125I]CCK-8 specifically bound to the membrane of the transfectant, and this binding was displaced by unlabeled CCK-8 with an IC50 of 0.32 nM. Treatment of these cells with CCK-8 increased the intracellular Ca2+ concentration with an EC50 of 0.30 nM. Using these cells expressing functional human CCKB/gastrin receptors, we investigated the pharmacological properties of (R)-1-[2,3-dihydro-1-(2'-methylphenacyl)-2-oxo-5-phenyl-1H-1, 4-benzodiazepin-3-yl]-3-(3-methylphenyl) urea (YM022), a potent and selective CCKB/gastrin receptor antagonist in rats. YM022 potently inhibited [125I]CCK-8 binding to the membrane with an IC50 of 55 pM and CCK-8-induced Ca2+ mobilization with that of 7.4 nM. On the other hand, its racemate and enantiomer more weakly inhibited this binding (IC50 of 110 pM and 11 nM, respectively) and Ca2+ mobilization (IC50 of 18 nM and 94 nM, respectively). These results indicate that YM022 stereoselectively recognizes the human CCKB/gastrin receptor as a potent antagonist and that the established transfectant is useful for characterization of human CCKB/gastrin-receptor ligands.
Koizumi
T
T
Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Ibaraki, Japan.
Saita
Y
Y
Miyake
A
A
Nishida
A
A
Yazawa
H
H
Honda
K
K
D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006727:Hormone Antagonists / Q000494:pharmacology*; D006801:Humans; D051381:Rats; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors* / Q000502:physiology; D012844:Sincalide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013045:Species Specificity; D013237:Stereoisomerism
D006727:Hormone Antagonists; D011949:Receptors, Cholecystokinin; D001569:Benzodiazepines; C087260:YM 022; D012844:Sincalide; D002118:Calcium