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Mukherjee M, Mukherjee C, Ghosh V, Jain A, Sadhukhan S, Dagar S, Sahu BS. Endoplasmic reticulum stress impedes regulated secretion by governing key exocytotic and granulogenic molecular switches. J Cell Sci 2024; 137:jcs261257. [PMID: 38348894 DOI: 10.1242/jcs.261257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 02/05/2024] [Indexed: 03/20/2024] Open
Abstract
Dense core vesicles (DCVs) and synaptic vesicles are specialised secretory vesicles in neurons and neuroendocrine cells, and abnormal release of their cargo is associated with various pathophysiologies. Endoplasmic reticulum (ER) stress and inter-organellar communication are also associated with disease biology. To investigate the functional status of regulated exocytosis arising from the crosstalk of a stressed ER and DCVs, ER stress was modelled in PC12 neuroendocrine cells using thapsigargin. DCV exocytosis was severely compromised in ER-stressed PC12 cells and was reversed to varying magnitudes by ER stress attenuators. Experiments with tunicamycin, an independent ER stressor, yielded similar results. Concurrently, ER stress also caused impaired DCV exocytosis in insulin-secreting INS-1 cells. Molecular analysis revealed blunted SNAP25 expression, potentially attributed to augmented levels of ATF4, an inhibitor of CREB that binds to the CREB-binding site. The effects of loss of function of ATF4 in ER-stressed cells substantiated this attribution. Our studies revealed severe defects in DCV exocytosis in ER-stressed cells for the first time, mediated by reduced levels of key exocytotic and granulogenic switches regulated via the eIF2α (EIF2A)-ATF4 axis.
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Affiliation(s)
- Mohima Mukherjee
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122052, India
| | | | - Vinayak Ghosh
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122052, India
| | - Aamna Jain
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122052, India
| | - Souren Sadhukhan
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122052, India
| | - Sushma Dagar
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122052, India
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Sheng W, Malagola E, Nienhüser H, Zhang Z, Kim W, Zamechek L, Sepulveda A, Hata M, Hayakawa Y, Zhao CM, Chen D, Wang TC. Hypergastrinemia Expands Gastric ECL Cells Through CCK2R + Progenitor Cells via ERK Activation. Cell Mol Gastroenterol Hepatol 2020; 10:434-449.e1. [PMID: 32330731 PMCID: PMC7371950 DOI: 10.1016/j.jcmgh.2020.04.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Enterochromaffin-like (ECL) cells in the stomach express gastrin/cholecystokinin 2 receptor CCK2R and are known to expand under hypergastrinemia, but whether this results from expansion of existing ECL cells or increased production from progenitors has not been clarified. METHODS We used mice with green fluorescent protein fluorescent reporter expression in ECL cells (histidine decarboxylase [Hdc]-green fluorescent protein), as well as Cck2r- and Hdc-driven Tamoxifen inducible recombinase Cre (Cck2r-CreERT2, Hdc-CreERT2) mice combined with Rosa26Sor-tdTomato (R26-tdTomato) mice, and studied their expression and cell fate in the gastric corpus by using models of hypergastrinemia (gastrin infusion, omeprazole treatment). RESULTS Hdc-GFP marked the majority of ECL cells, located in the lower third of the gastric glands. Hypergastrinemia led to expansion of ECL cells that was not restricted to the gland base, and promoted cellular proliferation (Ki67) in the gastric isthmus but not in basal ECL cells. Cck2r-CreERT2 mice marked most ECL cells, as well as scattered cell types located higher up in the glands, whose number was increased during hypergastrinemia. Cck2r-CreERT2+ isthmus progenitors, but not Hdc+ mature ECL cells, were the source of ECL cell hyperplasia during hypergastrinemia and could grow as 3-dimensional spheroids in vitro. Moreover, gastrin treatment in vitro promoted sphere formation from sorted Cck2r+Hdc- cells, and increased chromogranin A and phosphorylated- extracellular signal-regulated kinase expression in CCK2R-derived organoids. Gastrin activates extracellular signal-regulated kinase pathways in vivo and in vitro, and treatment with the Mitogen-activated protein kinase kinase 1 inhibitor U0126 blocked hypergastrinemia-mediated changes, including CCK2R-derived ECL cell hyperplasia in vivo as well as sphere formation and chromogranin A expression in vitro. CONCLUSIONS We show here that hypergastrinemia induces ECL cell hyperplasia that is derived primarily from CCK2R+ progenitors in the corpus. Gastrin-dependent function of CCK2R+ progenitors is regulated by the extracellular signal-regulated kinase pathway.
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Affiliation(s)
- Weiwei Sheng
- Division of Digestive and Liver Diseases, Department of Medicine,Department of Gastrointestinal Surgery, the First Hospital, China Medical University, Shenyang, China
| | - Ermanno Malagola
- Division of Digestive and Liver Diseases, Department of Medicine
| | - Henrik Nienhüser
- Division of Digestive and Liver Diseases, Department of Medicine
| | - Zhengyu Zhang
- Division of Digestive and Liver Diseases, Department of Medicine
| | - Woosook Kim
- Division of Digestive and Liver Diseases, Department of Medicine
| | - Leah Zamechek
- Division of Digestive and Liver Diseases, Department of Medicine
| | - Antonia Sepulveda
- Department of Pathology, Columbia University, College of Physicians and Surgeons, New York, New York
| | - Masahiro Hata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yoku Hayakawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Chun-Mei Zhao
- Department of Clinical and Molecular Medicine (Institutt for klinisk og molekylær medisin), Norwegian University of Science and Technology (Norges teknisk-naturvitenskaplige universitet), Trondheim, Norway
| | - Duan Chen
- Department of Clinical and Molecular Medicine (Institutt for klinisk og molekylær medisin), Norwegian University of Science and Technology (Norges teknisk-naturvitenskaplige universitet), Trondheim, Norway
| | - Timothy C. Wang
- Division of Digestive and Liver Diseases, Department of Medicine,Correspondence Address correspondence to: Timothy C. Wang, MD, Division of Digestive and Liver Disease, Department of Medicine, Columbia University Medical Center, New York, New York; fax: (212) 851-4590.
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Keller S, Kneissl J, Grabher-Meier V, Heindl S, Hasenauer J, Maier D, Mattes J, Winter P, Luber B. Evaluation of epidermal growth factor receptor signaling effects in gastric cancer cell lines by detailed motility-focused phenotypic characterization linked with molecular analysis. BMC Cancer 2017; 17:845. [PMID: 29237412 PMCID: PMC5729506 DOI: 10.1186/s12885-017-3822-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/22/2017] [Indexed: 12/21/2022] Open
Abstract
Background Gastric cancers frequently overexpress the epidermal growth factor receptor (EGFR), which has been implicated in pathological processes including tumor cell motility, invasion and metastasis. Targeting EGFR with the inhibitory antibody cetuximab may affect the motile and invasive behavior of tumor cells. Here, we evaluated the effects of EGFR signaling in gastric cancer cell lines to link the phenotypic behavior of the cells with their molecular characteristics. Methods Phenotypic effects were analyzed in four gastric cancer cell lines (AGS, Hs746T, LMSU and MKN1) by time-lapse microscopy and transwell invasion assay. Effects on EGFR signaling were detected using Western blot and proteome profiler analyses. A network was constructed linking EGFR signaling to the regulation of cellular motility. Results The analysis of the effects of treatment with epidermal growth factor (EGF) and cetuximab revealed that only one cell line (MKN1) was sensitive to cetuximab treatment in all phenotypic assays, whereas the other cell lines were either not responsive (Hs746T, LMSU) or sensitive only in certain tests (AGS). Cetuximab inhibited EGFR, MAPK and AKT activity and associated components of the EGFR signaling pathway to different degrees in cetuximab-sensitive MKN1 cells. In contrast, no such changes were observed in Hs746T cells. Thus, the different phenotypic behaviors of the cells were linked to their molecular response to treatment. Genetic alterations had different associations with response to treatment: while PIK3CA mutations and KRAS mutation or amplification were not obstructive, the MET mutation was associated with non-response. Conclusion These results identify components of the EGFR signaling network as important regulators of the phenotypic and molecular response to cetuximab treatment. Electronic supplementary material The online version of this article (10.1186/s12885-017-3822-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Simone Keller
- Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, München, Germany
| | - Julia Kneissl
- Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, München, Germany
| | - Verena Grabher-Meier
- Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, München, Germany
| | - Stefan Heindl
- Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, München, Germany
| | - Jan Hasenauer
- Institute of Computational Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764, Neuherberg, Germany.,Technische Universität München, Center for Mathematics, Chair of Mathematical Modelling of Biological Systems, Boltzmannstraße 3, 85748, Garching, Germany
| | - Dieter Maier
- Biomax Informatics AG, Robert-Koch-Str. 2, 82152, Planegg, Germany
| | - Julian Mattes
- Knowledge-Based Vision Systems, Software Competence Center Hagenberg GmbH, Softwarepark 21, 4232, Hagenberg, Austria.,Present Address: MATTES Medical Imaging GmbH, Softwarepark 21, 4232, Hagenberg, Austria
| | - Peter Winter
- GenXPro GmbH, Altenhöferallee 3, 60438, Frankfurt am Main, Germany
| | - Birgit Luber
- Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, München, Germany.
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Al Menhali A, Keeley TM, Demitrack ES, Samuelson LC. Gastrin induces parathyroid hormone-like hormone expression in gastric parietal cells. Am J Physiol Gastrointest Liver Physiol 2017; 312:G649-G657. [PMID: 28408643 PMCID: PMC5495916 DOI: 10.1152/ajpgi.00366.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/29/2017] [Accepted: 04/01/2017] [Indexed: 01/31/2023]
Abstract
Parietal cells play a fundamental role in stomach maintenance, not only by creating a pathogen-free environment through the production of gastric acid, but also by secreting growth factors important for homeostasis of the gastric epithelium. The gastrointestinal hormone gastrin is known to be a central regulator of both parietal cell function and gastric epithelial cell proliferation and differentiation. Our previous gene expression profiling studies of mouse stomach identified parathyroid hormone-like hormone (PTHLH) as a potential gastrin-regulated gastric growth factor. Although PTHLH is commonly overexpressed in gastric tumors, its normal expression, function, and regulation in the stomach are poorly understood. In this study we used pharmacologic and genetic mouse models as well as human gastric cancer cell lines to determine the cellular localization and regulation of this growth factor by the hormone gastrin. Analysis of PthlhLacZ/+ knock-in reporter mice localized Pthlh expression to parietal cells in the gastric corpus. Regulation by gastrin was demonstrated by increased Pthlh mRNA abundance after acute gastrin treatment in wild-type mice and reduced expression in gastrin-deficient mice. PTHLH transcripts were also observed in normal human stomach as well as in human gastric cancer cell lines. Gastrin treatment of AGS-E gastric cancer cells induced a rapid and robust increase in numerous PTHLH mRNA isoforms. This induction was largely due to increased transcriptional initiation, although analysis of mRNA half-life showed that gastrin treatment also extended the half-life of PTHLH mRNA, suggesting that gastrin regulates expression by both transcriptional and posttranscriptional mechanisms.NEW & NOTEWORTHY We show that the growth factor parathyroid hormone-like hormone (PTHLH) is expressed in acid-secreting parietal cells of the mouse stomach. We define the specific PTHLH mRNA isoforms expressed in human stomach and in human gastric cancer cell lines and show that gastrin induces PTHLH expression via transcription activation and mRNA stabilization. Our findings suggest that PTHLH is a gastrin-regulated growth factor that might contribute to gastric epithelial cell homeostasis.
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Affiliation(s)
- Asma Al Menhali
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Theresa M. Keeley
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Elise S. Demitrack
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Linda C. Samuelson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
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Abstract
Gastric cancer is the third leading cause of cancer-related mortality worldwide. Despite progress in understanding its development, challenges with treatment remain. Gastrin, a peptide hormone, is trophic for normal gastrointestinal epithelium. Gastrin also has been shown to play an important role in the stimulation of growth of several gastrointestinal cancers including gastric cancer. We sought to review the role of gastrin and its pathway in gastric cancer and its potential as a therapeutic target in the management of gastric cancer. In the normal adult stomach, gastrin is synthesized in the G cells of the antrum; however, gastrin expression also is found in many gastric adenocarcinomas of the stomach corpus. Gastrin's actions are mediated through the G-protein-coupled receptor cholecystokinin-B (CCK-B) on parietal and enterochromaffin cells of the gastric body. Gastrin blood levels are increased in subjects with type A atrophic gastritis and in those taking high doses of daily proton pump inhibitors for acid reflux disease. In experimental models, proton pump inhibitor-induced hypergastrinemia and infection with Helicobacter pylori increase the risk of gastric cancer. Understanding the gastrin:CCK-B signaling pathway has led to therapeutic strategies to treat gastric cancer by either targeting the CCK-B receptor with small-molecule antagonists or targeting the peptide with immune-based therapies. In this review, we discuss the role of gastrin in gastric adenocarcinoma, and strategies to block its effects to treat those with unresectable gastric cancer.
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Rohwer N, Bindel F, Grimm C, Lin SJ, Wappler J, Klinger B, Blüthgen N, Du Bois I, Schmeck B, Lehrach H, de Graauw M, Goncalves E, Saez-Rodriguez J, Tan P, Grabsch HI, Prigione A, Kempa S, Cramer T. Annexin A1 sustains tumor metabolism and cellular proliferation upon stable loss of HIF1A. Oncotarget 2017; 7:6693-710. [PMID: 26760764 PMCID: PMC4872743 DOI: 10.18632/oncotarget.6793] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 12/08/2015] [Indexed: 12/27/2022] Open
Abstract
Despite the approval of numerous molecular targeted drugs, long-term antiproliferative efficacy is rarely achieved and therapy resistance remains a central obstacle of cancer care. Combined inhibition of multiple cancer-driving pathways promises to improve antiproliferative efficacy. HIF-1 is a driver of gastric cancer and considered to be an attractive target for therapy. We noted that gastric cancer cells are able to functionally compensate the stable loss of HIF-1α. Via transcriptomics we identified a group of upregulated genes in HIF-1α-deficient cells and hypothesized that these genes confer survival upon HIF-1α loss. Strikingly, simultaneous knock-down of HIF-1α and Annexin A1 (ANXA1), one of the identified genes, resulted in complete cessation of proliferation. Using stable isotope-resolved metabolomics, oxidative and reductive glutamine metabolism was found to be significantly impaired in HIF-1α/ANXA1-deficient cells, potentially explaining the proliferation defect. In summary, we present a conceptually novel application of stable gene inactivation enabling in-depth deconstruction of resistance mechanisms. In theory, this experimental approach is applicable to any cancer-driving gene or pathway and promises to identify various new targets for combination therapies.
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Affiliation(s)
- Nadine Rohwer
- Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité, Berlin, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Fabian Bindel
- Berlin Institute for Medical Systems Biology, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | | | | | - Jessica Wappler
- GROW School of Oncology and Developmental Biology and Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Bertram Klinger
- Institute of Pathology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Integrative Research Institute (IRI) for The Life Sciences and Institute for Theoretical Biology, Humboldt-Universität Berlin, Berlin, Germany
| | - Nils Blüthgen
- Institute of Pathology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Integrative Research Institute (IRI) for The Life Sciences and Institute for Theoretical Biology, Humboldt-Universität Berlin, Berlin, Germany
| | - Ilona Du Bois
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University, Marburg, Germany
| | - Bernd Schmeck
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University, Marburg, Germany
| | - Hans Lehrach
- Max-Planck-Institut for Molecular Genetics, Berlin, Germany
| | - Marjo de Graauw
- Division of Toxicology, Leiden/Amsterdam Center for Drug Research, Leiden University, Amsterdam, The Netherlands
| | - Emanuel Goncalves
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Cambridge, United Kingdom
| | - Julio Saez-Rodriguez
- Joint Research Centre for Computational Biomedicine (JRC-COMBINE), RWTH Aachen University, Faculty of Medicine, Aachen, Germany
| | | | - Heike I Grabsch
- GROW School of Oncology and Developmental Biology and Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Stefan Kempa
- Berlin Institute for Medical Systems Biology, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Thorsten Cramer
- Molecular Tumor Biology, Department of General, Visceral and Transplantation Surgery, RWTH University Hospital, Aachen, Germany
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Baidal DA, Garber JR. Proton Pump Inhibitor–induced Hyperhidrosis: Important but Not Recognized. AACE Clin Case Rep 2016. [DOI: 10.4158/ep151167.cr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Sampurno S, Bijenhof A, Cheasley D, Xu H, Robine S, Hilton D, Alexander WS, Pereira L, Mantamadiotis T, Malaterre J, Ramsay RG. The Myb-p300-CREB axis modulates intestine homeostasis, radiosensitivity and tumorigenesis. Cell Death Dis 2013; 4:e605. [PMID: 23618903 PMCID: PMC3641342 DOI: 10.1038/cddis.2013.119] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The gastrointestinal (GI) epithelium is constantly renewing, depending upon the intestinal stem cells (ISC) regulated by a spectrum of transcription factors (TFs), including Myb. We noted previously in mice with a p300 mutation (plt6) within the Myb-interaction-domain phenocopied Myb hypomorphic mutant mice with regard to thrombopoiesis, and here, changes in GI homeostasis. p300 is a transcriptional coactivator for many TFs, most prominently cyclic-AMP response element-binding protein (CREB), and also Myb. Studies have highlighted the importance of CREB in proliferation and radiosensitivity, but not in the GI. This prompted us to directly investigate the p300–Myb–CREB axis in the GI. Here, the role of CREB has been defined by generating GI-specific inducible creb knockout (KO) mice. KO mice show efficient and specific deletion of CREB, with no evident compensation by CREM and ATF1. Despite complete KO, only modest effects on proliferation, radiosensitivity and differentiation in the GI under homeostatic or stress conditions were evident, even though CREB target gene pcna (proliferating cell nuclear antigen) was downregulated. creb and p300 mutant lines show increased goblet cells, whereas a reduction in enteroendocrine cells was apparent only in the p300 line, further resembling the Myb hypomorphs. When propagated in vitro, crebKO ISC were defective in organoid formation, suggesting that the GI stroma compensates for CREB loss in vivo, unlike in MybKO studies. Thus, it appears that p300 regulates GI differentiation primarily through Myb, rather than CREB. Finally, active pCREB is elevated in colorectal cancer (CRC) cells and adenomas, and is required for the expression of drug transporter, MRP2, associated with resistance to Oxaliplatin as well as several chromatin cohesion protein that are relevant to CRC therapy. These data raise the prospect that CREB may have a role in GI malignancy as it does in other cancer types, but unlike Myb, is not critical for GI homeostasis.
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Affiliation(s)
- S Sampurno
- Differentiation and Transcription Laboratory, Peter MacCallum Cancer Center,East Melbourne, Victoria, Australia
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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Liu T, Jose PA. Gastrin induces sodium-hydrogen exchanger 3 phosphorylation and mTOR activation via a phosphoinositide 3-kinase-/protein kinase C-dependent but AKT-independent pathway in renal proximal tubule cells derived from a normotensive male human. Endocrinology 2013; 154:865-75. [PMID: 23275470 PMCID: PMC3548178 DOI: 10.1210/en.2012-1813] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Gastrin is natriuretic, but its renal molecular targets and signal transduction pathways are not fully known. In this study, we confirmed the existence of CCKBR (a gastrin receptor) in male human renal proximal tubule cells and discovered that gastrin induced S6 phosphorylation, a downstream component of the phosphatidylinositol 3 kinase (PI3 kinase)-mammalian target of rapamycin pathway. Gastrin also increased the phosphorylation of sodium-hydrogen exchanger 3 (NHE3) at serine 552, caused its internalization, and decreased its expression at the cell surface and NHE activity. The phosphorylation of NHE3 and S6 was dependent on PI3 kinases because it was blocked by 2 different PI3-kinase inhibitors, wortmannin and LY294,002. The phosphorylation of NHE3 and S6 was not affected by the protein kinase A inhibitor H-89 but was blocked by a pan-PKC (chelerythrine) and a conventional PKC (cPKC) inhibitor (Gö6976) (10 μM) and an intracellular calcium chelator, 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester, suggesting the importance of cPKC and intracellular calcium in the gastrin signaling pathway. The cPKC involved was probably PKCα because it was phosphorylated by gastrin. The gastrin-mediated phosphorylation of NHE3, S6, and PKCα was via phospholipase C because it was blocked by a phospholipase C inhibitor, U73122 (10 μM). The phosphorylation (activation) of AKT, which is usually upstream of mammalian target of rapamycin in the classic PI3 kinase-AKT-p70S6K signaling pathway, was not affected, suggesting that the gastrin-induced phosphorylation of NHE3 and S6 is dependent on both PI3 kinase and PKCα but not AKT.
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Affiliation(s)
- Tianbing Liu
- Center for Molecular Physiology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue, Washington, DC 20010, USA.
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Abstract
When cellular reducing enzymes fail to shield the cell from increased amounts of reactive oxygen species (ROS), oxidative stress arises. The redox state is misbalanced, DNA and proteins are damaged and cellular transcription networks are activated. This condition can lead to the initiation and/or to the progression of atherosclerosis, tumors or pulmonary hypertension; diseases that are decisively furthered by the presence of oxidizing agents. Redox sensitive genes, like the zinc finger transcription factor early growth response 1 (Egr-1), play a pivotal role in the pathophysiology of these diseases. Apart from inducing apoptosis, signaling partners like the MEK/ERK pathway or the protein kinase C (PKC) can activate salvage programs such as cell proliferation that do not ameliorate, but rather worsen their outcome. Here, we review the currently available data on Egr-1 related signal transduction cascades in response to oxidative stress in the progression of epidemiologically significant diseases. Knowing the molecular pathways behind the pathology will greatly enhance our ability to identify possible targets for the development of new therapeutic strategies.
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12
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Mosli HH, Dennis A, Kocha W, Asher LJ, Van Uum SHM. Effect of short-term proton pump inhibitor treatment and its discontinuation on chromogranin A in healthy subjects. J Clin Endocrinol Metab 2012; 97:E1731-5. [PMID: 22723311 DOI: 10.1210/jc.2012-1548] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
CONTEXT Chromogranin A (CgA) is used as a generic tumor marker for neuroendocrine tumors. Proton pump inhibitors (PPI) are known to increase CgA, but it is not clear to what extent, and there is little information on how long PPI need to be discontinued before the effect of PPI has disappeared. Furthermore, is it not known whether this PPI effect is dependent on the CgA assay used. OBJECTIVE The aim of the study was to determine the effect of 7-d treatment with a PPI and its discontinuation on CgA in serum and plasma comparing four CgA assays. DESIGN AND PARTICIPANTS Seventeen healthy subjects took lansoprazole 30 mg at bedtime for 7 d, and blood samples for CgA were obtained at baseline, d 7 of PPI use, and 1, 2, 4, and 7 d after discontinuation of the PPI. In all samples, CgA was measured using the following assays: Alpco (serum and plasma), Cis-Bio (serum and plasma), DAKO, and Cis-Bio radioisotope assay. RESULTS When using the same assay, CgA was higher in plasma than in serum. Treatment with a PPI for 1 wk resulted in a significant (about 2.5-fold) increase in CgA with significant interindividual variation. After discontinuation of PPI, serum CgA gradually declined, with a half-life of 4-5 d. CONCLUSION Short-term PPI use results in a significant increase of CgA in serum and plasma, an effect that is largely independent of the assay used. PPI need to be discontinued for 2 wk to fully eliminate their effect on CgA. This effect of PPI needs to be considered when interpreting results of CgA measurements.
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Affiliation(s)
- Hala H Mosli
- 1. Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada N6A 3K7. 2. Department of
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Stress Triggered Changes in Expression of Genes for Neurosecretory Granules in Adrenal Medulla. Cell Mol Neurobiol 2011; 32:795-800. [DOI: 10.1007/s10571-011-9785-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/10/2011] [Indexed: 10/14/2022]
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Nørsett KG, Steele I, Duval C, Sammut SJ, Murugesan SVM, Kenny S, Rainbow L, Dimaline R, Dockray GJ, Pritchard DM, Varro A. Gastrin stimulates expression of plasminogen activator inhibitor-1 in gastric epithelial cells. Am J Physiol Gastrointest Liver Physiol 2011; 301:G446-53. [PMID: 21193525 PMCID: PMC3174540 DOI: 10.1152/ajpgi.00527.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Plasminogen activator inhibitor (PAI)-1 is associated with cancer progression, fibrosis and thrombosis. It is expressed in the stomach but the mechanisms controlling its expression there, and its biological role, are uncertain. We sought to define the role of gastrin in regulating PAI-1 expression and to determine the relevance for gastrin-stimulated cell migration and invasion. In gastric biopsies from subjects with elevated plasma gastrin, the abundances of PAI-1, urokinase plasminogen activator (uPA), and uPA receptor (uPAR) mRNAs measured by quantitative PCR were increased compared with subjects with plasma concentrations in the reference range. In patients with hypergastrinemia due to autoimmune chronic atrophic gastritis, there was increased abundance of PAI-1, uPA, and uPAR mRNAs that was reduced by octreotide or antrectomy. Immunohistochemistry revealed localization of PAI-1 to parietal cells and enterochromaffin-like cells in micronodular neuroendocrine tumors in hypergastrinemic subjects. Transcriptional mechanisms were studied by using a PAI-1-luciferase promoter-reporter construct transfected into AGS-G(R) cells. There was time- and concentration-dependent increase of PAI-1-luciferase expression in response to gastrin that was reversed by inhibitors of the PKC and MAPK pathways. In Boyden chamber assays, recombinant PAI-1 inhibited gastrin-stimulated AGS-G(R) cell migration and invasion, and small interfering RNA treatment increased responses to gastrin. We conclude that elevated plasma gastrin concentrations are associated with increased expression of gastric PAI-1, which may act to restrain gastrin-stimulated cell migration and invasion.
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Affiliation(s)
| | | | | | | | - Senthil V. M. Murugesan
- 1Physiological Laboratory and ,2Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | | | | | | | | | - D. Mark Pritchard
- 2Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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15
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Adler A, Park YD, Larsen P, Nagarajan V, Wollenberg K, Qiu J, Myers TG, Williamson PR. A novel specificity protein 1 (SP1)-like gene regulating protein kinase C-1 (Pkc1)-dependent cell wall integrity and virulence factors in Cryptococcus neoformans. J Biol Chem 2011; 286:20977-90. [PMID: 21487010 DOI: 10.1074/jbc.m111.230268] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Eukaryotic cells utilize complex signaling systems to detect their environments, responding and adapting as new conditions arise during evolution. The basidiomycete fungus Cryptococcus neoformans is a leading cause of AIDS-related death worldwide and utilizes the calcineurin and protein kinase C-1 (Pkc1) signaling pathways for host adaptation and expression of virulence. In the present studies, a C-terminal zinc finger transcription factor, homologous both to the calcineurin-responsive zinc fingers (Crz1) of ascomycetes and to the Pkc1-dependent specificity protein-1 (Sp1) transcription factors of metazoans, was identified and named SP1 because of its greater similarity to the metazoan factors. Structurally, the Cryptococcus neoformans Sp1 (Cn Sp1) protein was found to have acquired an additional zinc finger motif from that of Crz1 and showed Pkc1-dependent phosphorylation, nuclear localization, and whole genome epistatic associations under starvation conditions. Transcriptional targets of Cn Sp1 shared functional similarities with Crz1 factors, such as cell wall synthesis, but gained the regulation of processes involved in carbohydrate metabolism, including trehalose metabolism, and lost others, such as the induction of autophagy. In addition, overexpression of Cn Sp1 in a pkc1Δ mutant showed restoration of altered phenotypes involved in virulence, including cell wall stability, nitrosative stress, and extracellular capsule production. Cn Sp1 was also found to be important for virulence of the fungus using a mouse model. In summary, these data suggest an evolutionary shift in C-terminal zinc finger proteins during fungal evolution, transforming them from calcineurin-dependent to PKC1-dependent transcription factors, helping to shape the role of fungal pathogenesis of C. neoformans.
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Affiliation(s)
- Amos Adler
- Section of Pediatric Infectious Disease, Department of Pediatrics, University of Chicago, Chicago, Illinois 60637, USA
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16
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Creb and Sp/Krüppel response elements cooperate to control rat TRH gene transcription in response to cAMP. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:191-9. [PMID: 21266205 DOI: 10.1016/j.bbagrm.2011.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 01/18/2011] [Accepted: 01/20/2011] [Indexed: 12/17/2022]
Abstract
Expression of hypophysiotropic TRH, that controls thyroid axis activity, is increased by cold exposure; this effect is mimicked in rat hypothalamic cells incubated with norepinephrine or cAMP analogs. TRH proximal promoter contains three putative CRE: Site-4 or CRE-1 that overlaps an element recognized by thyroid hormone receptors, CRE-2 with adjacent sequences GC box or CACCC recognized by Sp/Krüppel factors (extended CRE-2), and AP-1 sites flanking a GRE(1/2). To evaluate the role of each element in the cAMP response, these sites were mutated or deleted in rat TRH promoter linked to luciferase gene (TRH-luc) and co-transfected with β-gal expression vector in various cell lines; C6 cells gave the highest response to forskolin. Basal activity was most affected by mutations or deletion of CRE-2 site, or CACCC (50-75% of wild type-WT). Forskolin-induced 3× stimulation in WT which decreased 25% with CRE-1 or AP-1 deletions, but 50% when CRE-2 or its 5' adjacent GC box was altered. SH-SY5Y cells co-transfected with CREB-expression vector increased dB-cAMP response in the wild type but not in the CRE-2 mutated plasmid; cotransfecting CREB-A (a dominant negative expression vector) strongly diminished basal or cAMP response. Primary cultures of hypothalamic cells transfected with plasmids containing deletions of CRE-1, CRE-2, or extended CRE-2 failed to respond to forskolin when CRE-2 was modified. These results corroborate the CRE-2 site as the main cAMP-response element of rat TRH promoter, not exclusive of transcription factors of hypothalamic cells, and stress the relevance of adjacent Sp-1 sites, important mediators of some metabolic hormones.
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Rohwer N, Dame C, Haugstetter A, Wiedenmann B, Detjen K, Schmitt CA, Cramer T. Hypoxia-inducible factor 1alpha determines gastric cancer chemosensitivity via modulation of p53 and NF-kappaB. PLoS One 2010; 5:e12038. [PMID: 20706634 PMCID: PMC2919384 DOI: 10.1371/journal.pone.0012038] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 07/19/2010] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Reduced chemosensitivity of solid cancer cells represents a pivotal obstacle in clinical oncology. Hence, the molecular characterization of pathways regulating chemosensitivity is a central prerequisite to improve cancer therapy. The hypoxia-inducible factor HIF-1alpha has been linked to chemosensitivity while the underlying molecular mechanisms remain largely elusive. Therefore, we comprehensively analysed HIF-1alpha's role in determining chemosensitivity focussing on responsible molecular pathways. METHODOLOGY AND PRINCIPAL FINDINGS RNA interference was applied to inactivate HIF-1alpha or p53 in the human gastric cancer cell lines AGS and MKN28. The chemotherapeutic agents 5-fluorouracil and cisplatin were used and chemosensitivity was assessed by cell proliferation assays as well as determination of cell cycle distribution and apoptosis. Expression of p53 and p53 target proteins was analyzed by western blot. NF-kappaB activity was characterized by means of electrophoretic mobility shift assay. Inactivation of HIF-1alpha in gastric cancer cells resulted in robust elevation of chemosensitivity. Accordingly, HIF-1alpha-competent cells displayed a significant reduction of chemotherapy-induced senescence and apoptosis. Remarkably, this phenotype was completely absent in p53 mutant cells while inactivation of p53 per se did not affect chemosensitivity. HIF-1alpha markedly suppressed chemotherapy-induced activation of p53 and p21 as well as the retinoblastoma protein, eventually resulting in cell cycle arrest. Reduced formation of reactive oxygen species in HIF-1alpha-competent cells was identified as the molecular mechanism of HIF-1alpha-mediated inhibition of p53. Furthermore, loss of HIF-1alpha abrogated, in a p53-dependent manner, chemotherapy-induced DNA-binding of NF-kappaB and expression of anti-apoptotic NF-kappaB target genes. Accordingly, reconstitution of the NF-kappaB subunit p65 reversed the increased chemosensitivity of HIF-1alpha-deficient cells. CONCLUSION AND SIGNIFICANCE In summary, we identified HIF-1alpha as a potent regulator of p53 and NF-kappaB activity under conditions of genotoxic stress. We conclude that p53 mutations in human tumors hold the potential to confound the efficacy of HIF-1-inhibitors in cancer therapy.
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Affiliation(s)
- Nadine Rohwer
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin, Berlin, Germany
- Molekulares Krebsforschungszentrum, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Christof Dame
- Klinik für Neonatologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Anja Haugstetter
- Molekulares Krebsforschungszentrum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Bertram Wiedenmann
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Katharina Detjen
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Molekulares Krebsforschungszentrum, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Clemens A. Schmitt
- Molekulares Krebsforschungszentrum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Thorsten Cramer
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Molekulares Krebsforschungszentrum, Charité - Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Blocking gastrin and CCK-B autocrine loop affects cell proliferation and apoptosis in vitro. Mol Cell Biochem 2010; 343:133-41. [PMID: 20559691 DOI: 10.1007/s11010-010-0507-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 06/02/2010] [Indexed: 01/15/2023]
Abstract
Gastrin and cholecystokinin-B receptor (CCK-B) were co-expressed in human gastric carcinoma tissues, suggesting that a functional autocrine loop, the gastrin and CCK-B receptor loop, may be presented in gastric cancer cells and play an important role in the pathogenesis and progression of gastric carcinomas. The present study was aimed at studying the effects of blocking the gastrin and CCK-B receptor loop on cell proliferation and apoptosis in gastric cancer cell line SGC-7901 cells (SGC-7901 cells). First, the expression of gastrin and CCK-B receptor mRNAs and gastrin protein in SGC-7901 cells were measured by RT-PCR and immunocytochemistry, respectively. Radioimmunoassay (RIA) was used to detect the concentrations of gastrin in culture medium. The gastrin-CCK-B receptor axis was blocked by using a specific neutralizing antibody against human gastrin and siRNA specifically targeting human CCK-B receptors, respectively. Flow cytometry was used to measure the cell cycle and apoptotic cells, and western blotting was used to measure the expression of CCK-B receptor, caspase-3, and matrix metalloproteinase-2 (MMP-2) in cells. The results showed that SGC-7901 cells not only coexpressed gastrin and CCK-B receptor mRNAs, but also endogenously secreted gastrin protein into the culture medium, thus forming gastrin-CCK-B receptor autocrine loop. Biologically, disrupting gastrin-CCK-B receptor autocrine loop by neutralizing the endogenous gastrin or by knocking down CCK-B receptor expression significantly inhibited the cell proliferation and decreased the percentage of cells residing in the S-phase of the cell cycle, and meanwhile promoted cell apoptosis and increased caspase-3 expression as well as decreased MMP-2 expression. An autocrine loop between endogenously secreted gastrin and CCK-B receptors may play a key role in the regulation of cell proliferation and apoptosis in SGC-7901 cells.
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Daskalow K, Rohwer N, Raskopf E, Dupuy E, Kühl A, Loddenkemper C, Wiedenmann B, Schmitz V, Cramer T. Role of hypoxia-inducible transcription factor 1alpha for progression and chemosensitivity of murine hepatocellular carcinoma. J Mol Med (Berl) 2010; 88:817-27. [PMID: 20383692 DOI: 10.1007/s00109-010-0623-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 02/10/2010] [Accepted: 03/15/2010] [Indexed: 12/13/2022]
Abstract
Hepatocellular carcinoma (HCC) is a hypervascularized tumor entity with association of arterial vessel density with poor prognosis. The hypoxia-inducible transcription factor HIF-1alpha represents a pivotal regulator of angiogenesis and is thought to determine the angiogenic nature of HCC. However, the precise role of HIF-1alpha during the pathogenesis of HCC remains elusive. We established a functional inactivation of HIF-1alpha in vitro and in vivo via RNAi and Cre/loxP-mediated recombination, respectively, to determine HIF-1alpha's role for tumor growth and chemosensitivity in transgenic and orthotopic murine HCC models. HIF-1alpha-deficient HCC cells displayed significantly reduced anchorage-independent growth and enhanced sensitivity toward etoposide, while basic cellular proliferation was unaffected. Analysis of gross tumor growth failed to detect reduced growth of HIF-1alpha-deficient tumors in the orthotopic and the transgenic HCC model, respectively. In line with the in vitro data, treatment of HIF-1alpha-deficient tumors with etoposide resulted in greater antiproliferative efficacy when compared to wild-type mice. Taken together, our study does not support a pivotal role of HIF-1alpha for tumor growth and angiogenesis in two murine HCC models. However, our data point toward a significant function of HIF-1alpha in determining chemosensitivity of HCC and therefore warrant validation of HIF-1alpha-inhibitors as adjuvant therapeutic agents in clinical studies of human HCC.
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Affiliation(s)
- Katjana Daskalow
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany
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20
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Jeon SJ, Bak HR, Seo JE, Kwon KJ, Kang YS, Kim HJ, Cheong JH, Ryu JH, Ko KH, Shin CY. Synergistic Increase of BDNF Release from Rat Primary Cortical Neuron by Combination of Several Medicinal Plant-Derived Compounds. Biomol Ther (Seoul) 2010. [DOI: 10.4062/biomolther.2010.18.1.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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21
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Chen YQ, Xie X. Podophyllotoxin induces CREB phosphorylation and CRE-driven gene expression via PKA but not MAPKs. Mol Cells 2010; 29:41-50. [PMID: 20033853 DOI: 10.1007/s10059-010-0015-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 10/15/2009] [Accepted: 10/20/2009] [Indexed: 12/11/2022] Open
Abstract
CRE-driven luciferase reporter is commonly used in drug screening systems involving G protein-coupled receptors (GPCRs). In a screen campaign designed to search for melanocortin-4 receptor (MC4R) agonists, podophyllotoxin, a microtubules disruptor, was found to induce cAMP-responsive element (CRE)-driven reporter expression. MC4R was not involved because podophyllotoxin induced CREB activation and CRE-driven transcription in cells not expressing MC4R. Previous studies indicated that intracellular calcium, PKA, and MAPKs are involved in CREB phosphorylation and activation. Our studies revealed that podophyllotoxin did not affect intracellular calcium level and the phosphorylation state of p38. Podophyllotoxin induced JNK and ERK activation, but blockade of JNK and ERK activation with specific inhibitors had no effect on podophyllotoxin-induced CREB activation and CRE-regulated gene expression. Further experiments revealed that H89, a specific inhibitor of PKA, significantly inhibited podophyllotoxin-induced CREB activation. Podophyllotoxin itself did not alter intracellular cAMP level. Taken together, podophyllotoxin induces CREB activation and CRE-driven gene expression via PKA activation by a cAMP-independent mechanism.
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Affiliation(s)
- Ya Qiong Chen
- State Key Laboratory of Drug Research, National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
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Abstract
Gastric adenocarcinoma is characterised by rapid emergence of systemic metastases, resulting in poor prognosis due to vanished curative treatment options. Better understanding of the molecular basis of gastric cancer spread is needed to design innovative treatments. The transcription factor HIF-1α (hypoxia-inducible factor 1α) is frequently overexpressed in human gastric cancer, and inhibition of HIF-1α has proven antitumour efficacy in rodent models, whereas the relevance of HIF-1α for the metastatic phenotype of gastric adenocarcinoma remains elusive. Therefore, we have conducted a comprehensive analysis of the role of HIF-1α for pivotal metastasis-associated processes of human gastric cancer. Immunhistochemistry for HIF-1α showed specific staining at the invading tumour edge in 90% of human gastric cancer samples, whereas normal gastric tissue was negative and only a minority of early gastric cancers (T1 tumours) showed specific staining. Hypoxia-inducible factor 1α-deficient cells showed a significant reduction of migratory, invasive and adhesive properties in vitro. Furthermore, the HIF-1α-inhibitor 2-methoxy-estradiol significantly reduced metastatic properties of gastric cancer cells. The accentuated expression at the invading edge together with the in vitro requirement of HIF-1α for migration, invasion and adherence argues for a pivotal role of HIF-1α in local invasion and, ultimately, systemic tumour spread. These results warrant the exploration of HIF-1α-inhibiting substances in clinical treatment studies of advanced gastric cancer.
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Rohwer N, Welzel M, Daskalow K, Pfander D, Wiedenmann B, Detjen K, Cramer T. Hypoxia-inducible factor 1alpha mediates anoikis resistance via suppression of alpha5 integrin. Cancer Res 2009; 68:10113-20. [PMID: 19074877 DOI: 10.1158/0008-5472.can-08-1839] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The transcription factor hypoxia-inducible factor 1 (HIF-1) alpha is abundantly expressed in the majority of human carcinomas and their metastases. HIF-1alpha controls central metastasis-associated pathways such as glycolysis, angiogenesis, and invasion. Functional inhibition of HIF-1alpha leads to impaired metastasis formation in murine tumor models. However, the precise molecular mechanisms underlying the metastasis-promoting role of HIF-1alpha have not been fully characterized. The ability of transformed epithelial cells to initiate the metastatic cascade relies on their ability to escape anoikis, a default program of apoptosis induction following loss of integrin anchoring to the extracellular matrix. Therefore, we addressed the function of HIF-1alpha in anoikis resistance and anchorage-independent growth. Inhibition of HIF-1alpha via RNA interference resulted in up-regulation of alpha5 integrin on the cell surface of human gastric cancer cells, whereas other integrins remained unaffected. Integrin alpha5 induction occurred at the level of transcription and was dependent on elevated intracellular superoxide in HIF-1alpha-knockdown cells. HIF-1alpha-deficient cells displayed significantly increased anoikis susceptibility due to up-regulated alpha5 integrin. Finally, colony formation in soft agar was shown to be dependent on HIF-1alpha as HIF-1alpha-deficient cells displayed a 70% reduction in anchorage-independent proliferation. Results obtained by RNA interference could be entirely confirmed by application of the pharmacologic HIF-1alpha-inhibitor 2-methoxyestradiol. Hence, our data argue for a pivotal role for HIF-1alpha in anoikis control via suppression of alpha5 integrin. HIF-1alpha-inhibiting drugs might therefore offer an innovative strategy for antimetastatic cancer therapy.
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Affiliation(s)
- Nadine Rohwer
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum and Freie Universität Berlin, Fachbereich Biologie, Pharmazie, Berlin, Germany
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Saha A, Hammond CE, Gooz M, Smolka AJ. The role of Sp1 in IL-1beta and H. pylori-mediated regulation of H,K-ATPase gene transcription. Am J Physiol Gastrointest Liver Physiol 2008; 295:G977-86. [PMID: 18772363 PMCID: PMC2584829 DOI: 10.1152/ajpgi.90338.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Helicobacter pylori infection of the gastric body induces transient hypochlorhydria and contributes to mucosal progression toward gastric carcinoma. Acid secretion is mediated by parietal cell H,K-ATPase, in which the catalytic alpha-subunit (HKalpha) promoter activity in transfected gastric epithelial [gastric adenocarcinoma (AGS)] cells is repressed by H. pylori through NF-kappaB p50 homodimer binding to the promoter. IL-1beta, an acid secretory inhibitor whose mucosal level is increased by H. pylori, upregulates HKalpha promoter activity in AGS cells. Because IL-1beta also activates NF-kappaB signaling, we investigated disparate HKalpha regulation by H. pylori and IL-1beta, testing the hypothesis that IL-1beta-induced HKalpha promoter activation is mediated by the transcription factor Sp1. DNase I footprinting revealed Sp1 binding to the HKalpha promoter at -56 to -39 bp. IL-1beta stimulated the activity of three HKalpha promoter constructs containing NF-kappaB and Sp1 sites transfected into AGS cells and also stimulated a construct containing only an Sp1 site. This stimulation was abrogated by mutating the HKalpha promoter Sp1 binding site. Gelshift assays showed that IL-1beta increased Sp1 but not p50 binding to cognate HKalpha probes and that Sp1 also interacts with an HKalpha NF-kappaB site when bound to its cognate HKalpha cis-response element. H. pylori did not augment Sp1 binding to an HKalpha Sp1 probe, and small interfering RNA-mediated knockdown of Sp1 expression abrogated IL-1beta-induced HKalpha promoter stimulation. We conclude that IL-1beta upregulates HKalpha gene transcription by inducing Sp1 binding to HKalpha Sp1 and NF-kappaB sites and that the H. pylori perturbation of HKalpha gene expression is independent of Sp1-mediated basal HKalpha transcription.
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Affiliation(s)
- Arindam Saha
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Charles E. Hammond
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Monika Gooz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Adam J. Smolka
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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