NF-κB is activated in response to temozolomide in an AKT-dependent manner and confers protection against the growth suppressive effect of the drug

J Transl Med. 2012 Dec 21:10:252. doi: 10.1186/1479-5876-10-252.


Background: Most DNA-damaging chemotherapeutic agents activate the transcription factor nuclear factor κB (NF-κB). However, NF-κB activation can either protect from or contribute to the growth suppressive effects of the agent. We previously showed that the DNA-methylating drug temozolomide (TMZ) activates AKT, a positive modulator of NF-κB, in a mismatch repair (MMR) system-dependent manner. Here we investigated whether NF-κB is activated by TMZ and whether AKT is involved in this molecular event. We also evaluated the functional consequence of inhibiting NF-κB on tumor cell response to TMZ.

Methods: AKT phosphorylation, NF-κB transcriptional activity, IκB-α degradation, NF-κB2/p52 generation, and RelA and NF-κB2/p52 nuclear translocation were investigated in TMZ-treated MMR-deficient (HCT116, 293TLα-) and/or MMR-proficient (HCT116/3-6, 293TLα+, M10) cells. AKT involvement in TMZ-induced activation of NF-κB was addressed in HCT116/3-6 and M10 cells transiently transfected with AKT1-targeting siRNA or using the isogenic MMR-proficient cell lines pUSE2 and KD12, expressing wild type or kinase-dead mutant AKT1. The effects of inhibiting NF-κB on sensitivity to TMZ were investigated in HCT116/3-6 and M10 cells using the NF-κB inhibitor NEMO-binding domain (NBD) peptide or an anti-RelA siRNA.

Results: TMZ enhanced NF-κB transcriptional activity, activated AKT, induced IκB-α degradation and RelA nuclear translocation in HCT116/3-6 and M10 but not in HCT116 cells. In M10 cells, TMZ promoted NF-κB2/p52 generation and nuclear translocation and enhanced the secretion of IL-8 and MCP-1. TMZ induced RelA nuclear translocation also in 293TLα+ but not in 293TLα- cells. AKT1 silencing inhibited TMZ-induced IκB-α degradation and NF-κB2/p52 generation. Up-regulation of NF-κB transcriptional activity and nuclear translocation of RelA and NF-κB2/p52 in response to TMZ were impaired in KD12 cells. RelA silencing in HCT116/3-6 and M10 cells increased TMZ-induced growth suppression. In M10 cells NBD peptide reduced basal NF-κB activity, abrogated TMZ-induced up-regulation of NF-κB activity and increased sensitivity to TMZ. In HCT116/3-6 cells, the combined treatment with NBD peptide and TMZ produced additive growth inhibitory effects.

Conclusion: NF-κB is activated in response to TMZ in a MMR- and AKT-dependent manner and confers protection against drug-induced cell growth inhibition. Our findings suggest that a clinical benefit could be obtained by combining TMZ with NF-κB inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • Cell Proliferation / drug effects
  • Cellular Senescence / drug effects
  • Cytoprotection / drug effects*
  • DNA Mismatch Repair / drug effects
  • Dacarbazine / analogs & derivatives*
  • Dacarbazine / pharmacology
  • Drug Screening Assays, Antitumor
  • HCT116 Cells
  • HEK293 Cells
  • Humans
  • I-kappa B Proteins / metabolism
  • MCF-7 Cells
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Peptides / pharmacology
  • Phosphorylation / drug effects
  • Protein Transport / drug effects
  • Proteolysis / drug effects
  • Proto-Oncogene Proteins c-akt / metabolism*
  • RNA Interference / drug effects
  • Temozolomide
  • Transcription Factor RelA / metabolism
  • Transcription, Genetic / drug effects


  • I-kappa B Proteins
  • NF-kappa B
  • NFKBIA protein, human
  • Peptides
  • Transcription Factor RelA
  • NF-KappaB Inhibitor alpha
  • Dacarbazine
  • Proto-Oncogene Proteins c-akt
  • Temozolomide