HDAC2 deficiency sensitizes colon cancer cells to TNFalpha-induced apoptosis through inhibition of NF-kappaB activity

Exp Cell Res. 2008 Apr 15;314(7):1507-18. doi: 10.1016/j.yexcr.2008.01.010. Epub 2008 Jan 19.

Abstract

HDAC inhibitors exert potent anti-tumorigenic and anti-inflammatory activity. Their effects are selective for transformed cells, and we recently demonstrated that transformation of epithelial cells with k-Ras sensitizes cells to HDACi induced apoptosis. The aim of this study was to determine whether the ability of HDACi to modulate signaling by a major pro-inflammatory cytokine, TNFalpha, is also restricted to cells that harbor mutant k-Ras. We used the system of two isogenic cell lines that differ by the presence of mutant k-Ras, HCT116 and Hke3 cells. Treatment of cells with TNFalpha alone did not induce apoptosis; however HDACi potentiated TNFalpha-induced apoptosis in both HCT116 and Hke3 cells. Thus, the ability of HDACi to sensitize cells to TNFalpha-induced apoptosis appears to be k-Ras independent. We demonstrated that HDACi inhibited TNFalpha-induced NF-kappaB transcriptional and DNA binding activity in both cell lines, underlying the increased apoptosis in cells treated with both agents. We showed that overexpression of HDAC2 enhanced TNFalpha-induced NF-kappaB activity and that silencing of HDAC2 decreased NF-kappaB activity. Finally, silencing of HDAC2 expression was sufficient to sensitize colon cancer cells to TNFalpha-induced apoptosis. The ability of HDACi to interfere with NF-kappaB activity is likely to contribute to their potent anti-tumorigenic and anti-inflammatory activity.

MeSH terms

  • Apoptosis / drug effects*
  • Caspase 9 / metabolism
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • Cell Proliferation / drug effects
  • Colonic Neoplasms / enzymology*
  • Colonic Neoplasms / pathology*
  • DNA / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Gene Silencing / drug effects
  • HCT116 Cells
  • Histone Deacetylase 2
  • Histone Deacetylase Inhibitors
  • Histone Deacetylases / deficiency*
  • Humans
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / genetics
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • Repressor Proteins / antagonists & inhibitors
  • Transcription Factor RelA / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology*
  • bcl-X Protein / genetics
  • ras Proteins / metabolism

Substances

  • Enzyme Inhibitors
  • Histone Deacetylase Inhibitors
  • NF-kappa B
  • Repressor Proteins
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • bcl-X Protein
  • DNA
  • Caspase 9
  • Histone Deacetylase 2
  • Histone Deacetylases
  • ras Proteins