title: Insulin, CCAAT/enhancer-binding proteins and lactate regulate the human 11β-hydroxysteroid dehydrogenase type 2 gene expression in colon cancer cell lines.
abstract: 11β-Hydroxysteroid dehydrogenases (11beta-HSD) modulate mineralocorticoid receptor transactivation by glucocorticoids and regulate access to the glucocorticoid receptor. The isozyme 11beta-HSD2 is selectively expressed in mineralocorticoid target tissues and its activity is reduced in various disease states with abnormal sodium retention and hypertension, including the apparent mineralocorticoid excess. As 50% of patients with essential hypertension are insulin resistant and hyperinsulinemic, we hypothesized that insulin downregulates the 11beta-HSD2 activity. In the present study we show that insulin reduced the 11beta-HSD2 activity in cancer colon cell lines (HCT116, SW620 and HT-29) at the transcriptional level, in a time and dose dependent manner. The downregulation was reversible and required new protein synthesis. Pathway analysis using mRNA profiling revealed that insulin treatment modified the expression of the transcription factor family C/EBPs (CCAAT/enhancer-binding proteins) but also of glycolysis related enzymes. Western blot and real time PCR confirmed an upregulation of C/EBP beta isoforms (LAP and LIP) with a more pronounced increase in the inhibitory isoform LIP. EMSA and reporter gene assays demonstrated the role of C/EBP beta isoforms in HSD11B2 gene expression regulation. In addition, secretion of lactate, a byproduct of glycolysis, was shown to mediate insulin-dependent HSD11B2 downregulation. In summary, we demonstrate that insulin downregulates HSD11B2 through increased LIP expression and augmented lactate secretion. Such mechanisms are of interest and potential significance for sodium reabsorption in the colon.
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Andrieu
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Pierre
authors.initials: P
authors.lastname: Fustier
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Rasoul
authors.initials: R
authors.lastname: Alikhani-Koupaei
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Irena D
authors.initials: ID
authors.lastname: Ignatova
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Guettinger
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Felix J
authors.initials: FJ
authors.lastname: Frey
authors.affiliation: Department of Nephrology & Hypertension and Clinical Pharmacology and Department of Clinical Research, University Hospital of Berne, Berne, Switzerland.
authors.forename: Brigitte M
authors.initials: BM
authors.lastname: Frey
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000235:genetics* / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D003106:Colon / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D007328:Insulin; D019344:Lactic Acid; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2