Inhibition of PRC2 histone methyltransferase activity increases TRAIL-mediated apoptosis sensitivity in human colon cancer cells

J Cell Physiol. 2013 Apr;228(4):764-72. doi: 10.1002/jcp.24224.


Colorectal cancer is ranked among the top leading causes of cancer death in industrialized populations. Polycomb group proteins, including Suz12 and Ezh2, are epigenetic regulatory proteins that act as transcriptional repressors of many differentiation-associated genes and are overexpressed in a large subset of colorectal cancers. Retinoic acid (RA) acts as a negative regulator of PcG actions in stem cells, but has shown limited therapeutic potential in some solid tumors, including colorectal cancer, in part because of retinoic acid receptor β silencing. Through treatment with RA, Suz12 shRNA knockdown, or Ezh2 pharmacological inhibition with 3-deazaneplanocin A (DZNep), we increased TRAIL-mediated apoptosis in human colorectal cancer cell lines. This increased apoptosis in human colon cancer cells after RA or DZNep treatment was associated with a ~2.5-fold increase in TNFRSF10B (DR5) transcript levels and a 42% reduction in the H3K27me3 epigenetic mark at the TNFRSF10B promoter after DZNep addition. Taken together, our findings indicate that pharmacological inhibition of Polycomb repressive complex 2 histone methyltransferase activity may constitute a new epigenetic therapeutic strategy to overcome RA non-responsiveness in a subset of colorectal tumors by increasing TRAIL-mediated apoptosis sensitivity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives
  • Adenosine / pharmacology
  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Cell Line, Tumor
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / metabolism*
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Enhancer of Zeste Homolog 2 Protein
  • Epigenomics
  • HT29 Cells
  • Histone Methyltransferases
  • Histone-Lysine N-Methyltransferase / antagonists & inhibitors*
  • Histone-Lysine N-Methyltransferase / genetics
  • Histone-Lysine N-Methyltransferase / metabolism
  • Humans
  • MCF-7 Cells
  • Neoplasm Proteins
  • Polycomb Repressive Complex 2 / antagonists & inhibitors*
  • Polycomb Repressive Complex 2 / genetics
  • Polycomb Repressive Complex 2 / metabolism
  • Promoter Regions, Genetic / drug effects
  • RNA, Small Interfering / antagonists & inhibitors
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / genetics
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism
  • TNF-Related Apoptosis-Inducing Ligand / genetics
  • TNF-Related Apoptosis-Inducing Ligand / metabolism*
  • Transcription Factors
  • Tretinoin / pharmacology


  • DNA-Binding Proteins
  • Neoplasm Proteins
  • RNA, Small Interfering
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • SUZ12 protein, human
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFRSF10B protein, human
  • TNFSF10 protein, human
  • Transcription Factors
  • 3-deazaneplanocin
  • Tretinoin
  • Histone Methyltransferases
  • EZH2 protein, human
  • Enhancer of Zeste Homolog 2 Protein
  • Histone-Lysine N-Methyltransferase
  • Polycomb Repressive Complex 2
  • Adenosine