Activation of NF-kappaB binding in HT-29 colon cancer cells by inhibition of phosphatidylinositol 3-kinase

Biochem Biophys Res Commun. 2000 Jul 14;273(3):853-8. doi: 10.1006/bbrc.2000.3034.

Abstract

The ubiquitous transcription factor NF-kappaB, which is activated in cells by diverse stimuli including phosphatidylinositol 3-kinase (PI3-kinase), is a critical factor for cell survival and growth. Inhibition of PI3-kinase enhances enterocyte-like differentiation of the human colon cancer cell line HT-29. The purpose of our study was to determine whether PI3-kinase alters NF-kappaB in HT-29 cells. Wortmannin, a specific PI3-kinase inhibitor, stimulated NF-kappaB binding activity in HT-29 cells by 4 h after treatment. Activation of NF-kappaB occurred without degradation of IkappaBalpha, a protein that sequesters NF-kappaB in the cytosol. In addition to increasing NF-kappaB binding, either wortmannin or cotransfection with a dominant negative mutant of the p85 regulatory subunit of PI3-kinase (Deltap85) induced NF-kappaB transactivation. Taken together, these results suggest that inhibition of PI3-kinase in HT-29 cells results in induction of NF-kappaB binding activity and transactivation which is independent of IkappaBalpha degradation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Colonic Neoplasms / metabolism*
  • Colonic Neoplasms / pathology
  • DNA-Binding Proteins / metabolism
  • Enzyme Inhibitors / pharmacology*
  • HT29 Cells
  • Humans
  • Hydrolysis
  • I-kappa B Proteins*
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors*
  • Protein Binding
  • Transfection

Substances

  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • I-kappa B Proteins
  • NF-kappa B
  • NFKBIA protein, human
  • Phosphoinositide-3 Kinase Inhibitors
  • NF-KappaB Inhibitor alpha