title: Digoxin and ouabain increase the synthesis of cholesterol in human liver cells.
abstract: Digoxin and ouabain are steroid drugs that inhibit the Na(+)/K(+)-ATPase, and are widely used in the treatment of heart diseases. They may also have additional effects, such as on metabolism of steroid hormones, although until now no evidence has been provided about the effects of these cardioactive glycosides on the synthesis of cholesterol. Here we report that digoxin and ouabain increased the synthesis of cholesterol in human liver HepG2 cells, enhancing the activity and the expression of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the rate-limiting enzyme of the cholesterol synthesis. This effect was mediated by the binding of the sterol regulatory element binding protein-2 (SREBP-2) to the HMGCR promoter, and was lost in cells silenced for SREBP-2 or loaded with increasing amounts of cholesterol. Digoxin and ouabain competed with cholesterol for binding to the SREBP-cleavage-activating protein, and are critical regulators of cholesterol synthesis in human liver cells.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Torino, and Research Center on Experimental Medicine (CeRMS), Via Santena, 5/bis, 10126, Torino, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Campia
authors.forename: E
authors.initials: E
authors.lastname: Gazzano
authors.forename: G
authors.initials: G
authors.lastname: Pescarmona
authors.forename: D
authors.initials: D
authors.lastname: Ghigo
authors.forename: A
authors.initials: A
authors.lastname: Bosia
authors.forename: C
authors.initials: C
authors.lastname: Riganti
mesh_terms: D002316:Cardiotonic Agents / Q000494:pharmacology*; D002784:Cholesterol / Q000096:biosynthesis*; D004077:Digoxin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects*; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D008148:Lovastatin / Q000031:analogs & derivatives / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology*; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics / Q000378:metabolism; D014451:Ubiquinone / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D004791:Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C497390:SREBF2 protein, human; D051782:Sterol Regulatory Element Binding Protein 2; D014451:Ubiquinone; C012258:mevastatin; D010042:Ouabain; D004077:Digoxin; D002784:Cholesterol; D008148:Lovastatin; D006903:Hydroxymethylglutaryl CoA Reductases