Inhibitory role of E2F-1 in the regulation of tumor suppressor p53 during DNA damage response

Biochem Biophys Res Commun. 2012 Apr 27;421(1):57-63. doi: 10.1016/j.bbrc.2012.03.108. Epub 2012 Mar 29.

Abstract

Appropriate regulation of DNA damage response is pivotal for maintaining genome stability. p53 as well as E2F-1 plays a critical role during DNA damage response, however, the physiological significance of their interaction has been elusive. In the present study, we found that E2F-1 has an inhibitory effect on p53 during adriamycin (ADR)-mediated DNA damage response. Upon ADR exposure, p53 and E2F-1 were markedly induced at protein and mRNA levels in p53-procifient U2OS and HCT116 cells, and formed a stable complex as examined by co-immunoprecipitation experiments. Of note, chromatin immunoprecipitation (ChIP) experiments revealed that ADR-mediated induction coincides with the efficient recruitment of p53 and E2F-1 onto the promoters of p53-target genes, such as p21(WAF1) and BAX. Subsequent RT-PCR and luciferase reporter assays demonstrated that E2F-1 strongly attenuates p53-dependent transactivation of p53-target genes. Importantly, siRNA-mediated knockdown of E2F-1 stimulated apoptosis in response to ADR, which was associated with an accelerated response of p21(WAF1) and BAX. Collectively, our present findings suggest that E2F-1 participates in p53-mediated DNA damage response and might have a checkpoint function to limit overactive p53.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / genetics*
  • Cell Line, Tumor
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • DNA Damage / genetics*
  • Doxorubicin / pharmacology
  • E2F1 Transcription Factor / genetics
  • E2F1 Transcription Factor / metabolism*
  • Gene Knockdown Techniques
  • Humans
  • RNA, Small Interfering / genetics
  • Transcription, Genetic
  • Tumor Suppressor Protein p53 / antagonists & inhibitors*
  • Tumor Suppressor Protein p53 / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • RNA, Small Interfering
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • Doxorubicin