title: Zinc Ions Mediate Gastrin Expression, Proliferation, and Migration Downstream of the Cholecystokinin-2 Receptor.
abstract: Gastrin, acting via the cholecystokinin-2 receptor (CCK2R), activates its own promoter in a positive-feed-forward loop that may result in hypergastrinemia. Activity of the gastrin promoter is also stimulated by exogenous Zn2+ions. Here, the role of intracellular zinc and calcium signaling in the gastrin positive-feed-forward loop was investigated. Gastrin promoter activity was measured in the human gastric carcinoma cell line AGS-CCK2R and in Jurkat cells transfected with various gastrin promoter-luciferase constructs after treatment with gastrin in the presence and absence of zinc- and calcium-chelating agents. The free intracellular zinc ion concentrations were measured in the same cells with the fluorescent indicator FluoZin-3. Cell proliferation and migration/invasion were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cell proliferation assay and in Boyden chamber assays, respectively. The zinc chelator N,N,N,N-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN) abolished gastrin-stimulated gastrin promoter activity, and the inhibition was completely reversed by exogenous Zn2+ions. In contrast, the calcium chelator 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM) potentiated gastrin-stimulated gastrin promoter activity. Treatment with gastrin increased the intracellular concentration of free Zn2+ions, and the increase was blocked by TPEN, but not by BAPTA-AM. TPEN also inhibited the stimulation of cell proliferation and migration/invasion by gastrin, but BAPTA-AM had no effect. These results, which are the first report of the existence of Zn2+signaling downstream of CCK2R activation, suggest that zinc chelation therapies may be effective in counteracting gastrin-dependent tumor growth.
authors: Department of Surgery, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
authors: Mike
authors: M
authors: Chang
authors: Department of Surgery, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
authors: Lin
authors: L
authors: Xiao
authors: Department of Surgery, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
authors: Arthur
authors: A
authors: Shulkes
authors: Department of Surgery, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
authors: Graham S
authors: GS
authors: Baldwin
authors: Department of Surgery, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
authors: Oneel
authors: O
authors: Patel
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005029:Ethylenediamines / Q000494:pharmacology; D005755:Gastrins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D011401:Promoter Regions, Genetic; D043887:Receptor, Cholecystokinin B / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D002614:Chelating Agents; D005029:Ethylenediamines; D005755:Gastrins; D043887:Receptor, Cholecystokinin B; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D015032:Zinc; C044387:N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine