Inhibition of hypoxia-inducible factor-1alpha (HIF-1alpha) protein synthesis by DNA damage inducing agents

PLoS One. 2010 May 7;5(5):e10522. doi: 10.1371/journal.pone.0010522.

Abstract

Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor that is composed of a hypoxia-inducible alpha subunit (HIF-1alpha and HIF-2alpha) and a constitutively expressed beta subunit (HIF-1beta). HIF mediates the adaptation of cells and tissues to low oxygen concentrations. It also plays an important role in tumorigenesis and constitutes an important therapeutic target in anti-tumor therapy. We have screened a number of reported HIF inhibitors for their effects on HIF-transcriptional activity and found that the DNA damage inducing agents camptothecin and mitomycin C produced the most robust effects. Camptothecin is a reported inhibitor of HIF-1alpha translation, while mitomycin C has been reported to induce p53-dependent HIF-1alpha degradation. In this study we demonstrate that the inhibitory effect of mitomycin C on HIF-1alpha protein expression is not dependent on p53 and protein degradation, but also involves HIF-1alpha translational regulation. Initiation of a DNA damage response with the small molecule p53 activator NSC-652287 (RITA) has been reported to inhibit HIF-1alpha protein synthesis by increasing the phosphorylation of eIF2alpha. However, we show here that even when eIF2alpha phosphorylation is prevented, the DNA damage inducing drugs mitomycin C, camptothecin and NSC-652287 still inhibit HIF-1alpha protein synthesis to the same extent. The inhibitory effects of camptothecin on HIF-1alpha expression but not that of mitomycin C and NSC-652287 were dependent on cyclin-dependent kinase activity. In conclusion, specific types of DNA damage can bring about selective inhibition of HIF-1alpha protein synthesis. Further characterization of the involved mechanisms may reveal important novel therapeutic targets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions / genetics
  • Apoptosis / drug effects
  • Camptothecin / pharmacology*
  • Cell Hypoxia / drug effects
  • Cell Line
  • Cyclin-Dependent Kinases / metabolism
  • DNA Damage*
  • Etoposide / pharmacology
  • Eukaryotic Initiation Factor-2 / metabolism
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / biosynthesis*
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Mitomycin / pharmacology*
  • Phosphorylation / drug effects
  • Protein Biosynthesis / drug effects*
  • Protein Processing, Post-Translational / drug effects
  • Signal Transduction / drug effects
  • Transcription, Genetic / drug effects
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • 5' Untranslated Regions
  • Eukaryotic Initiation Factor-2
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Tumor Suppressor Protein p53
  • Mitomycin
  • Etoposide
  • Cyclin-Dependent Kinases
  • Camptothecin