Fas-mediated apoptosis in cholangiocarcinoma cells is enhanced by 3,3'-diindolylmethane through inhibition of AKT signaling and FLICE-like inhibitory protein

Am J Pathol. 2006 Nov;169(5):1833-42. doi: 10.2353/ajpath.2006.060234.


Stimulation of Fas-mediated apoptosis has been promoted as a potential therapy for many cancers, including cholangiocarcinoma. We have previously reported that Fas-resistant, but not Fas-sensitive, cholangiocarcinoma cells are tumorigenic in nude mice. The present studies sought to identify molecular targets that promote Fas-mediated apoptosis in cholangiocarcinoma. We found that Fas-resistant cholangiocarcinoma cells exhibited increased constitutive phosphorylation of AKT compared with Fas-sensitive cells. Increased phosphorylation of AKT was also demonstrated in human cholangiocarcinoma tumors and was evident in a mouse xenograft cholangiocarcinoma model. Furthermore, we found that 3,3'-diindolylmethane (DIM), a vegetable autolysis product, promoted Fas-mediated apoptosis of cholangiocarcinoma cells. DIM inhibited phosphorylation of AKT and activation of FLICE-like-inhibitory-protein (FLIP). Inhibition of phosphatidylinositol 3-kinase/AKT decreased FLIP activation and promoted Fas-mediated apoptosis. By contrast, adenovirus-mediated constitutively activated AKT protected cholangiocarcinoma cells from Fas-mediated apoptosis. Decreased activation of extracellular signal-regulated kinase and nuclear factor-kappaB and increased activation of caspase-3, -8, and -9 were associated with inhibition of AKT and FLIP. These results support AKT and FLIP as potential molecular targets and DIM as a potent compound for cholangiocarcinoma intervention.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenoviridae / metabolism
  • Animals
  • Anticarcinogenic Agents / pharmacology
  • Apoptosis / drug effects*
  • CASP8 and FADD-Like Apoptosis Regulating Protein / antagonists & inhibitors*
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Caspases / metabolism
  • Cholangiocarcinoma / pathology*
  • Enzyme Activation / drug effects
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Female
  • Genes, Dominant
  • Humans
  • Indoles / pharmacology*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • NF-kappa B / metabolism
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Signal Transduction / drug effects*
  • Xenograft Model Antitumor Assays
  • fas Receptor / metabolism*


  • Anticarcinogenic Agents
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • FAS protein, human
  • Indoles
  • NF-kappa B
  • Phosphoinositide-3 Kinase Inhibitors
  • fas Receptor
  • indole-3-carbinol
  • Proto-Oncogene Proteins c-akt
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • Caspases
  • 3,3'-diindolylmethane