KGF induces lipogenic genes through a PI3K and JNK/SREBP-1 pathway in H292 cells

J Lipid Res. 2005 Dec;46(12):2624-35. doi: 10.1194/jlr.M500154-JLR200. Epub 2005 Sep 14.

Abstract

Lipid synthesis is required for cell growth and is subject to pharmacologic regulation. Keratinocyte growth factor (KGF) stimulates proliferation and lipogenesis in H292 cells, a pulmonary epithelial cancer cell line, but the signaling pathways are not known. KGF stimulated the expression of the transcription factors sterol-regulatory element binding protein-1 (SREBP-1), CCAAT/enhancer binding protein alpha (C/EBPalpha), and C/EBPdelta and two key enzymes involved in lipogenesis, FAS and stearoyl coenzyme A desaturase-1 (SCD-1). We found that KGF induced rapid activation of Akt, p70 S6K, JNK, and extracellular signal-regulated (ERK). Induction of SREBP-1, SCD-1, and FAS by KGF was inhibited by the JNK inhibitor SP600125 and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 but not by the ERK inhibitor PD98059. Using FAS and SCD-1-luciferase promoter constructs, we observed that KGF stimulated the transcription of these promoters and that exogenous cholesterol inhibited the induction. Mutation of the SREBP-1 binding site in the SCD-1 promoter abolished the effect of KGF on SCD-1 transcription. In addition, overexpression of active SREBP-1 directly stimulated SCD-1 and FAS. Conversely, adenovirus-mediated overexpression of a dominant negative form of SREBP-1 inhibited the KGF effect on FAS and SCD-1 expression. In summary, we conclude that KGF requires both PI3K and JNK signaling pathways to induce SREBP-1, which in turn induces SCD-1 and FAS expression in H292 cells.

Publication types

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

MeSH terms

  • Adenoviridae / genetics
  • CCAAT-Enhancer-Binding Proteins / metabolism
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cholesterol / pharmacology
  • Fas Ligand Protein
  • Fibroblast Growth Factor 7 / pharmacology*
  • Gene Expression Regulation / drug effects
  • Genes, Reporter / genetics
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • Lipids* / genetics
  • Membrane Glycoproteins / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Promoter Regions, Genetic / genetics
  • Signal Transduction / drug effects*
  • Stearoyl-CoA Desaturase / metabolism
  • Sterol Regulatory Element Binding Protein 1 / genetics
  • Sterol Regulatory Element Binding Protein 1 / metabolism*
  • Transcription, Genetic / genetics
  • Tumor Necrosis Factors / metabolism

Substances

  • CCAAT-Enhancer-Binding Proteins
  • FASLG protein, human
  • Fas Ligand Protein
  • Lipids
  • Membrane Glycoproteins
  • Sterol Regulatory Element Binding Protein 1
  • Tumor Necrosis Factors
  • Fibroblast Growth Factor 7
  • Cholesterol
  • Stearoyl-CoA Desaturase
  • Phosphatidylinositol 3-Kinases
  • JNK Mitogen-Activated Protein Kinases