title: Inducible cAMP early repressor suppresses gastrin-mediated activation of cyclin D1 and c-fos gene expression.
abstract: The gastric hormone gastrin and its precursors promote proliferation in several gastrointestinal cell types. Here we show that gastrin induces transcription of cell cycle gene cyclin D1 and protooncogene c-fos in the neuroendocrine pancreatic cell line AR42J and that this gastrin response is inhibited by endogenous inducible cAMP early repressor (ICER). The transcriptional repressor ICER is known to downregulate both its own expression and the expression of other genes containing cAMP-responsive elements (CREs). Using siRNA, we also show that CRE promoter elements are the targets of endogenous ICER in AR42J cells as well as in the neuroendocrine cell line RIN5F. Our results suggest that ICER plays an important role in molecular mechanisms governing gastrin-mediated growth by modulating gastrin's transcriptional activation of growth-related genes. Our finding that ICER modulates pituitary adenylate cyclase-activating polypeptide-activated gene expression also indicates a regulatory effect of ICER in the responses of neuroendocrine cells to peptides other than gastrin.
authors.affiliation: Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
authors.forename: Tonje S
authors.initials: TS
authors.lastname: Steigedal
authors.forename: Torunn
authors.initials: T
authors.lastname: Bruland
authors.forename: Kristine
authors.initials: K
authors.lastname: Misund
authors.forename: Liv
authors.initials: L
authors.lastname: Thommesen
authors.forename: Astrid
authors.initials: A
authors.lastname: Laegreid
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D051786:Cyclic AMP Response Element Modulator / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D056741:Cyclin D; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D005755:Gastrins / Q000378:metabolism* / Q000494:pharmacology; D015870:Gene Expression; D017930:Genes, Reporter; D007700:Kinetics; D008156:Luciferases; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection
chemical_list: C497412:Crem protein, rat; D056741:Cyclin D; D016213:Cyclins; D005755:Gastrins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D020033:Protein Isoforms; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051786:Cyclic AMP Response Element Modulator; D005576:Colforsin; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases