BACKGROUND & AIMS: Induction of immediate early transcription factors (ITF) represents the first transcriptional program controlling mitogen-stimulated cell cycle progression in cancer. Here, we examined the transcriptional mechanisms regulating the ITF protein c-Myc and its role in pancreatic cancer growth in vitro and in vivo. METHODS: Expression of ITF proteins was examined by reverse-transcription polymerase chain reaction and immunoblotting, and its implications in cell cycle progression and growth was determined by flow cytometry and [(3)H]-thymidine incorporation. Intracellular Ca(2+) concentrations, calcineurin activity, and cellular nuclear factor of activated T cells (NFAT) distribution were analyzed. Transcription factor complex formations and promoter regulation were examined by immunoprecipitations, reporter gene assays, and chromatin immunoprecipitation. Using a combination of RNA interference knockdown technology and xenograft models, we analyzed the significance for pancreatic cancer tumor growth. RESULTS: Serum promotes pancreatic cancer growth through induction of the proproliferative NFAT/c-Myc axis. Mechanistically, serum increases intracellular Ca(2+) concentrations and activates the calcineurin/NFAT pathway to induce c-Myc transcription. NFAT binds to a serum responsive element within the proximal promoter, initiates p300-dependent histone acetylation, and creates a local chromatin structure permissive for the inducible recruitment of Ets-like gene (ELK)-1, a protein required for maximal activation of the c-Myc promoter. The functional significance of this novel pathway was emphasized by impaired c-Myc expression, G1 arrest, and reduced tumor growth upon NFAT depletion in vitro and in vivo. CONCLUSIONS: Our study uncovers a novel mechanism regulating cell growth and identifies the NFAT/ELK complex as modulators of early stages of mitogen-stimulated proliferation in pancreatic cancer cells. Copyright 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.
BACKGROUND & AIMS: Induction of immediate early transcription factors (ITF) represents the first transcriptional program controlling mitogen-stimulated cell cycle progression in cancer. Here, we examined the transcriptional mechanisms regulating the ITF protein c-Myc and its role in pancreatic cancer growth in vitro and in vivo. METHODS: Expression of ITF proteins was examined by reverse-transcription polymerase chain reaction and immunoblotting, and its implications in cell cycle progression and growth was determined by flow cytometry and [(3)H]-thymidine incorporation. Intracellular Ca(2+) concentrations, calcineurin activity, and cellular nuclear factor of activated T cells (NFAT) distribution were analyzed. Transcription factor complex formations and promoter regulation were examined by immunoprecipitations, reporter gene assays, and chromatin immunoprecipitation. Using a combination of RNA interference knockdown technology and xenograft models, we analyzed the significance for pancreatic cancer tumor growth. RESULTS: Serum promotes pancreatic cancer growth through induction of the proproliferative NFAT/c-Myc axis. Mechanistically, serum increases intracellular Ca(2+) concentrations and activates the calcineurin/NFAT pathway to induce c-Myc transcription. NFAT binds to a serum responsive element within the proximal promoter, initiates p300-dependent histone acetylation, and creates a local chromatin structure permissive for the inducible recruitment of Ets-like gene (ELK)-1, a protein required for maximal activation of the c-Myc promoter. The functional significance of this novel pathway was emphasized by impaired c-Myc expression, G1 arrest, and reduced tumor growth upon NFAT depletion in vitro and in vivo. CONCLUSIONS: Our study uncovers a novel mechanism regulating cell growth and identifies the NFAT/ELK complex as modulators of early stages of mitogen-stimulated proliferation in pancreatic cancer cells. Copyright 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.
Authors: Bruno K Robbs; Andre L S Cruz; Miriam B F Werneck; Giuliana P Mognol; João P B Viola Journal: Mol Cell Biol Date: 2008-09-22 Impact factor: 4.272
Authors: V Baubet; H Le Mouellic; A K Campbell; E Lucas-Meunier; P Fossier; P Brúlet Journal: Proc Natl Acad Sci U S A Date: 2000-06-20 Impact factor: 11.205
Authors: Sandra Baumgart; Elisabeth Glesel; Garima Singh; Nai-Ming Chen; Kristina Reutlinger; Jinsan Zhang; Daniel D Billadeau; Martin E Fernandez-Zapico; Thomas M Gress; Shiv K Singh; Volker Ellenrieder Journal: Gastroenterology Date: 2011-11-10 Impact factor: 22.682
Authors: Angela L McCleary-Wheeler; Gwen A Lomberk; Frank U Weiss; Günter Schneider; Muller Fabbri; Tara L Poshusta; Nelson J Dusetti; Sandra Baumgart; Juan L Iovanna; Volker Ellenrieder; Raul Urrutia; Martin E Fernandez-Zapico Journal: Cancer Lett Date: 2012-10-13 Impact factor: 8.679