Her-2/neu overexpression induces NF-kappaB via a PI3-kinase/Akt pathway involving calpain-mediated degradation of IkappaB-alpha that can be inhibited by the tumor suppressor PTEN

Oncogene. 2001 Mar 15;20(11):1287-99. doi: 10.1038/sj.onc.1204257.


The Nuclear Factor (NF)-kappaB family of transcription factors controls expression of genes which promote cell growth, survival, and neoplastic transformation. Recently we demonstrated aberrant constitutive activation of NF-kappaB in primary human and rat breast cancer specimens and in cell lines. Overexpression of the epidermal growth factor receptor (EGFR) family member Her-2/neu, seen in approximately 30% of breast cancers, is associated with poor prognosis. Previously, Her-2/neu has been shown to signal via a phosphatidylinositol 3 (PI3)-kinase to Akt/protein kinase B (PKB) pathway. Since this signaling pathway was recently shown to activate NF-kappaB, here we have tested the hypothesis that Her-2/neu can activate NF-kappaB in breast cancer. Overexpression of Her-2/neu and EGFR-4 in Ba/F3 cells led to constitutive PI3- and Akt kinase activities, and induction of classical NF-kappaB (p50/p65). Similarly, a tumor cell line and tumors derived from MMTV-Her-2/neu transgenic mice displayed elevated levels of classical NF-kappaB. Engagement of Her-2/neu receptor downregulated the level of NF-kappaB. NF-kappaB binding and activity in the cultured cells was reduced upon inhibition of the PI3- to Akt kinase signaling pathway via ectopic expression of kinase inactive mutants, incubation with wortmannin, or expression of the tumor suppressor phosphatase PTEN. Inhibitors of calpain, but not the proteasome, blocked IkappaB-alpha degradation. Inhibition of Akt did not affect IKK activity. These results indicate that Her-2/neu activates NF-kappaB via a PI3- to Akt kinase signaling pathway that can be inhibited via the tumor suppressor PTEN, and is mediated by calpain rather than the IkappaB kinase complex.

Publication types

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

MeSH terms

  • Animals
  • Breast Neoplasms / metabolism*
  • Calpain / metabolism
  • DNA-Binding Proteins / metabolism
  • Female
  • Genes, Tumor Suppressor*
  • Humans
  • I-kappa B Proteins*
  • Mammary Neoplasms, Animal / metabolism
  • Mice
  • Mice, Transgenic
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / metabolism
  • PTEN Phosphohydrolase
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoric Monoester Hydrolases / metabolism*
  • Protein Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Receptor, ErbB-2 / metabolism*
  • Signal Transduction*
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins*


  • DNA-Binding Proteins
  • I-kappa B Proteins
  • NF-kappa B
  • NFKBIA protein, human
  • Nfkbia protein, mouse
  • Nfkbia protein, rat
  • Proto-Oncogene Proteins
  • Tumor Suppressor Proteins
  • NF-KappaB Inhibitor alpha
  • Receptor, ErbB-2
  • AKT1 protein, human
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Phosphoric Monoester Hydrolases
  • PTEN Phosphohydrolase
  • PTEN protein, human
  • Calpain