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Zhou G, Yu J, Wang A, Liu SH, Sinnett-Smith J, Wu J, Sanchez R, Nemunaitis J, Ricordi C, Rozengurt E, Brunicardi FC. Metformin Restrains Pancreatic Duodenal Homeobox-1 (PDX-1) Function by Inhibiting ERK Signaling in Pancreatic Ductal Adenocarcinoma. Curr Mol Med 2016; 16:83-90. [PMID: 26695692 PMCID: PMC4994969 DOI: 10.2174/1566524016666151222145551] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 11/20/2015] [Accepted: 12/15/2015] [Indexed: 02/06/2023]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is one of the most potent and perilous diseases known, with a median survival rate of 3-5 months due to the combination of only advanced stage diagnosis and ineffective therapeutic options. Metformin (1,1-Dimethylbiguanide hydrochloride), the leading drug used for type 2 diabetes mellitus, emerges as a potential therapy for PDAC and other human cancers. Metformin exerts its anticancer action via a variety of adenosine monophosphate (AMP)-activated protein kinase (AMPK)- dependent and/or AMPK-independent mechanisms. We present data here showing that metformin downregulated pancreatic transcription factor pancreatic duodenal homeobox-1 (PDX-1), suggesting a potential novel mechanism by which metformin exerts its anticancer action. Metformin inhibited PDX-1 expression at both protein and mRNA levels and PDX-1 transactivity as well in PDAC cells. Extracellular signal-regulated kinase (ERK) was identified as a PDX-1-interacting protein by antibody array screening in GFP-PDX-1 stable HEK293 cells. Co-transfection of ERK1 with PDX-1 resulted in an enhanced PDX-1 expression in HEK293 cells in a dose-dependent manner. Immunoprecipitation/Western blotting analysis confirmed the ERK-PDX-1 interaction in PANC-1 cells stimulated by epidermal growth factor (EGF). EGF induced an enhanced PDX-1 expression in PANC-1 cells and this stimulation was inhibited by MEK inhibitor PD0325901. Metformin inhibited EGF-stimulated PDX-1 expression with an accompanied inhibition of ERK kinase activation in PANC- 1 cells. Taken together, our studies show that PDX-1 is a potential novel target for metformin in PDAC cells and that metformin may exert its anticancer action in PDAC by down-regulating PDX-1 via a mechanism involving inhibition of ERK signaling.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - F C Brunicardi
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA, USA.
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Zhou G, Sinnett-Smith J, Liu SH, Yu J, Wu J, Sanchez R, Pandol SJ, Abrol R, Nemunaitis J, Rozengurt E, Brunicardi FC. Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin. Front Physiol 2014; 5:226. [PMID: 25009500 PMCID: PMC4069483 DOI: 10.3389/fphys.2014.00226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 05/31/2014] [Indexed: 01/29/2023] Open
Abstract
Somatostatin (SST) is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. SST’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5). SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1) is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.
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Affiliation(s)
- Guisheng Zhou
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Jim Sinnett-Smith
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Shi-He Liu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Juehua Yu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - James Wu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Robbi Sanchez
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Stephen J Pandol
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine at Cedars Sinai Medical Center Los Angeles, CA, USA ; Veterans Affairs Los Angeles, CA, USA
| | - Ravinder Abrol
- Materials and Process Simulation Center, California Institute of Technology Pasadena, CA, USA
| | - John Nemunaitis
- Gradalis, Inc., Dallas, TX, USA ; Mary Crowley Cancer Research Centers Dallas, TX, USA
| | - Enrique Rozengurt
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - F Charles Brunicardi
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA
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Liu SH, Zhou G, Yu J, Wu J, Nemunaitis J, Senzer N, Dawson D, Li M, Fisher WE, Brunicardi FC. Notch1 activation up-regulates pancreatic and duodenal homeobox-1. Genes (Basel) 2013; 4:358-74. [PMID: 24705209 PMCID: PMC3924823 DOI: 10.3390/genes4030358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/02/2013] [Accepted: 07/11/2013] [Indexed: 12/28/2022] Open
Abstract
Transcription factor pancreatic and duodenal homeobox-1 (PDX-1) plays an essential role in pancreatic development, β-cell differentiation, maintenance of normal β-cell function and tumorigenesis. PDX-1 expression is tightly controlled through a variety of mechanisms under different cellular contexts. We report here that overexpression of Notch1 intracellular domain (NICD), an activated form of Notch1, enhanced PDX-1 expression in both PDX-1 stable HEK293 cells and mouse insulinoma β-TC-6 cells, while NICD shRNA inhibited the enhancing effect. NICD-enhanced PDX-1 expression was accompanied by increased insulin expression/secretion and cell proliferation in β-TC-6 cells, which was reversed by NICD shRNA. Cre activation-induced specific expression of NICD in islet β cells of transgenic βNICD+/+ mice induced increased expression of PDX-1, insulin and proliferating cell nuclear antigen (PCNA) and decreased expression of p27 with accompanied fasting hyperinsulinemia and hypoglycemia and altered responses to intraperitoneal glucose tolerance test. Systemically delivered NICD shRNA suppressed islet expression of PDX-1 and reversed the hypoglycemia and hyperinsulinemia. Moreover, expression levels of NICD were correlated with those of PDX-1 in human pancreatic neuroendocrine tumor. Thus, Notch1 acts as a positive regulator for PDX-1 expression, cooperates with PDX-1 in the development of insulin overexpression and islet cell neoplasia and represents a potential therapeutic target for islet neoplasia.
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Affiliation(s)
- Shi-He Liu
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
| | - Guisheng Zhou
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
| | - Juehua Yu
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
| | - James Wu
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
| | | | - Neil Senzer
- Mary Crowley Cancer Research Center, Dallas, TX 75230, USA.
| | - David Dawson
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
| | - Min Li
- Department of Neurosurgery, UT-Houston School of Medicine, Houston, TX 77030, USA.
| | - William E Fisher
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
| | - F Charles Brunicardi
- Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA.
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de Barros Reis MA, Arantes VC, Cunha DA, Latorraca MQ, Toyama MH, Carneiro EM, Boschero AC. Increased L-CPT-1 activity and altered gene expression in pancreatic islets of malnourished adult rats: a possible relationship between elevated free fatty acid levels and impaired insulin secretion. J Nutr Biochem 2007; 19:85-90. [PMID: 17531461 DOI: 10.1016/j.jnutbio.2007.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 12/29/2006] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
Intrauterine growth restriction is associated with chronically elevated levels of serum fatty acids and reduced glucose-stimulated insulin secretion. Lipid metabolism in pancreatic beta cells is critical for the regulation of insulin secretion, and the chronic exposure to fatty acids results in higher palmitate oxidation rates and an altered insulin response to glucose. Using a rat model of isocaloric protein restriction, we examined whether pre- and postnatal protein malnutrition influences the properties of pancreatic islet carnitine palmitoyltransferase-1 (liver isoform, L-CPT-1), a rate-limiting enzyme that regulates fatty acid oxidation in mitochondria. The activity of L-CPT-1 in pancreatic islets increased in the low protein (LP), although the L-CPT-1 mRNA levels were unaffected by malnutrition. The susceptibility of enzyme to inhibition by malonyl-CoA was unaltered and the content of malonyl-CoA was reduced in LP cells. Because the mitochondrial oxidation of fatty acids is related to the altered expression of a number of genes encoding proteins involved in insulin secretion, the levels of expression of insulin and GLUT-2 mRNA were assessed. A reduced expression of both genes was observed in malnourished rats. These results provide further evidence that increased L-CPT-1 activity and changes in gene expression in pancreatic islets may be involved in the reduced insulin secretion seen in malnourished rats.
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