Sulforaphane sensitizes tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant hepatoma cells to TRAIL-induced apoptosis through reactive oxygen species-mediated up-regulation of DR5

Cancer Res. 2006 Feb 1;66(3):1740-50. doi: 10.1158/0008-5472.CAN-05-1568.

Abstract

Sulforaphane is a chemopreventive agent present in various cruciferous vegetables, including broccoli. Here, we show that treatment with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in combination with subtoxic doses of sulforaphane significantly induces rapid apoptosis in TRAIL-resistant hepatoma cells. Neither TNF-alpha- nor Fas-mediated apoptosis was sensitized in hepatoma cells by cotreatment with sulforaphane, suggesting that sulforaphane can selectively sensitize cells to TRAIL-induced apoptosis but not to apoptosis mediated by other death receptors. We found that sulforaphane treatment significantly up-regulated mRNA and protein levels of DR5, a death receptor of TRAIL. This was accompanied by an increase in the generation of reactive oxygen species (ROS). Pretreatment with N-acetyl-l-cysteine and overexpression of catalase inhibited sulforaphane-induced up-regulation of DR5 and almost completely blocked the cotreatment-induced apoptosis. Furthermore, the sulforaphane-mediated sensitization to TRAIL was efficiently reduced by administration of a blocking antibody or small interfering RNAs for DR5. These results collectively indicate that sulforaphane-induced generation of ROS and the subsequent up-regulation of DR5 are critical for triggering and amplifying TRAIL-induced apoptotic signaling. We also found that sulforaphane can sensitize both Bcl-xL- and Bcl-2-overexpressing hepatoma cells to TRAIL-induced apoptosis, indicating that treatment with a combination of TRAIL and sulforaphane may be a safe strategy for treating resistant hepatomas.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / administration & dosage
  • Apoptosis Regulatory Proteins / pharmacology*
  • Carcinoma, Hepatocellular / drug therapy*
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism
  • Cell Line, Tumor
  • Drug Screening Assays, Antitumor
  • Drug Synergism
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism
  • Humans
  • Inhibitor of Apoptosis Proteins / biosynthesis
  • Isothiocyanates
  • Liver Neoplasms / drug therapy*
  • Membrane Glycoproteins / administration & dosage
  • Membrane Glycoproteins / pharmacology*
  • Promoter Regions, Genetic / drug effects
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Rats
  • Reactive Oxygen Species / metabolism*
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • Receptors, Tumor Necrosis Factor / biosynthesis
  • Receptors, Tumor Necrosis Factor / genetics
  • Receptors, Tumor Necrosis Factor / metabolism*
  • Sulfoxides
  • TNF-Related Apoptosis-Inducing Ligand
  • Thiocyanates / administration & dosage
  • Thiocyanates / pharmacology*
  • Transcriptional Activation / drug effects
  • Tumor Necrosis Factor-alpha / administration & dosage
  • Tumor Necrosis Factor-alpha / pharmacology*
  • Up-Regulation
  • bcl-X Protein / biosynthesis

Substances

  • Apoptosis Regulatory Proteins
  • BCL2L1 protein, human
  • Inhibitor of Apoptosis Proteins
  • Isothiocyanates
  • Membrane Glycoproteins
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • Receptors, Tumor Necrosis Factor
  • Sulfoxides
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFRSF10B protein, human
  • TNFSF10 protein, human
  • Thiocyanates
  • Tnfrsf10b protein, rat
  • Tnfsf10 protein, rat
  • Tumor Necrosis Factor-alpha
  • bcl-X Protein
  • sulforaphane