Identification of a novel pro-apopotic function of NF-kappaB in the DNA damage response

J Cell Mol Med. 2009 Oct;13(10):4239-56. doi: 10.1111/j.1582-4934.2009.00888.x. Epub 2009 Sep 1.

Abstract

NF-kappaB is activated by DNA-damaging anticancer drugs as part of the cellular stress response. However, the consequences of drug-induced NF-kappaB activation are still only partly understood. To investigate the impact of NF-kappaB on the cell's response to DNA damage, we engineered glioblastoma cells that stably express mutant IkappaBalpha superrepressor (IkappaBalpha-SR) to block NF-kappaB activation. Here, we identify a novel pro-apoptotic function of NF-kappaB in the DNA damage response in glioblastoma cells. Chemotherapeutic drugs that intercalate into DNA and inhibit topoisomerase II such as Doxorubicin, Daunorubicin and Mitoxantrone stimulate NF-kappaB DNA binding and transcriptional activity prior to induction of cell death. Importantly, specific inhibition of drug-induced NF-kappaB activation by IkappaBalpha-SR or RNA interference against p65 significantly reduces apoptosis upon treatment with Doxorubicin, Daunorubicin or Mitoxantrone. NF-kappaB exerts this pro-apoptotic function especially after pulse drug exposure as compared to continuous treatment indicating that the contribution of NF-kappaB becomes relevant during the recovery phase following the initial DNA damage. Mechanistic studies show that NF-kappaB inhibition does not alter Doxorubicin uptake and efflux or cell cycle alterations. Genetic silencing of p53 by RNA interference reveals that NF-kappaB promotes drug-induced apoptosis in a p53-independent manner. Intriguingly, drug-mediated NF-kappaB activation results in a significant increase in DNA damage prior to the induction of apoptosis. By demonstrating that NF-kappaB promotes DNA damage formation and apoptosis upon pulse treatment with DNA intercalators, our findings provide novel insights into the control of the DNA damage response by NF-kappaB in glioblastoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis* / drug effects
  • Cell Cycle / drug effects
  • Cell Line, Tumor
  • DNA Damage*
  • DNA, Neoplasm / metabolism
  • Doxorubicin / metabolism
  • Doxorubicin / pharmacology
  • Glioblastoma / metabolism
  • Glioblastoma / pathology
  • Humans
  • Intercalating Agents / pharmacology
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism*
  • Protein Binding / drug effects
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / genetics
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • DNA, Neoplasm
  • Intercalating Agents
  • NF-kappa B
  • Tumor Suppressor Protein p53
  • Doxorubicin