Glucocorticoid (GC)-mediated down-regulation of urokinase plasminogen activator expression via the serum and GC regulated kinase-1/forkhead box O3a pathway

Endocrinology. 2008 May;149(5):2637-45. doi: 10.1210/en.2007-1096. Epub 2008 Jan 31.

Abstract

The glucocorticoid receptor (GR) and its ligand, cortisol, play a central role in human physiology. The exact mechanisms by which GR activation regulates these processes are the subject of intensive investigation. We and others have shown that GR activation can indirectly down-regulate specific genes via serum and glucocorticoid (GC) regulated kinase-1-mediated inhibition of forkhead box O3a (FOXO3a) transcriptional activity. We previously used gene expression microarrays, together with bioinformatic analyses, to identify putative FOXO3a target genes in breast epithelial cells. In this paper we refine our analysis through the use of FOXO3a chromatin immunoprecipitation (ChIP) microarrays. ChIP microarray results reveal urokinase plasminogen activator (uPA) as a putative novel target of FOXO3a in breast epithelial and breast cancer cell lines. We further show that uPA down-regulation after GC treatment requires serum and GC regulated kinase-1-mediated inactivation of FOXO3a activity. ChIP and luciferase assays confirm that FOXO3a can both occupy and transactivate the uPA promoter. Our data suggest that inactivation of FOXO3a after GR activation is an important mechanism contributing to GC-mediated repression of uPA gene expression in breast epithelial and cancer cells.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Binding Sites
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Cells, Cultured
  • Chromatin Immunoprecipitation
  • Conserved Sequence
  • Dexamethasone / pharmacology
  • Down-Regulation / drug effects
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / metabolism
  • Forkhead Transcription Factors / physiology*
  • Glucocorticoids / pharmacology*
  • Humans
  • Immediate-Early Proteins / physiology*
  • Mammary Glands, Human / metabolism
  • Models, Biological
  • Promoter Regions, Genetic
  • Protein Serine-Threonine Kinases / physiology*
  • RNA, Messenger / metabolism
  • Receptors, Glucocorticoid / metabolism
  • Signal Transduction / drug effects
  • Transfection
  • Urokinase-Type Plasminogen Activator / genetics*
  • Urokinase-Type Plasminogen Activator / metabolism

Substances

  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • Glucocorticoids
  • Immediate-Early Proteins
  • RNA, Messenger
  • Receptors, Glucocorticoid
  • Dexamethasone
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase
  • Urokinase-Type Plasminogen Activator