IRF-1 transcriptionally upregulates PUMA, which mediates the mitochondrial apoptotic pathway in IRF-1-induced apoptosis in cancer cells

Cell Death Differ. 2010 Apr;17(4):699-709. doi: 10.1038/cdd.2009.156. Epub 2009 Oct 23.


Interferon regulatory factor-1 (IRF-1) is a transcription factor that acts as a tumor suppressor and causes apoptosis in cancer cells. We evaluated IRF-1-induced apoptosis in gastric cancer cell lines. We established stable clones in AGS cells that have a tetracycline-inducible IRF-1 expression system. We used these clones and recombinant adenovirus expressing IRF-1 to explore the mechanism of IRF-1-induced apoptosis in gastric cancer. Expression of IRF-1 causes apoptosis in gastric cancer cell lines as shown by phosphatidylserine exposure and cleavage of caspase-8, caspase-3, and Bid with the mitochondrial release of cytochrome c. However, inhibition of caspase-8 and Bid did not inhibit apoptosis and did not decrease cleaved caspase-9 or mitochondrial release of cytochrome c. We then show that IRF-1 upregulates PUMA (p53 upregulated modulator of apoptosis), which is known to activate apoptosis by the intrinsic pathway; this can be p53-independent. IRF-1 binds to distinct sites in the promoter of PUMA and activates PUMA transcription. Moreover, molecular markers of mitochondrial apoptosis are eliminated in PUMA knockout and knockdown cells and phosphatidylserine exposure is decreased dramatically. Finally, we show that IFN-gamma induces IRF-1-mediated upregulation of PUMA in cancer cells. We conclude that IRF-1 can induce apoptosis by the intrinsic pathway independent of the extrinsic pathway by upregulation of PUMA.

Publication types

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

MeSH terms

  • Apoptosis / genetics*
  • Apoptosis / physiology
  • Apoptosis Regulatory Proteins / genetics*
  • Apoptosis Regulatory Proteins / metabolism
  • BH3 Interacting Domain Death Agonist Protein / metabolism
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cytochromes c / metabolism
  • Gene Expression Regulation, Neoplastic / physiology
  • Genetic Vectors / genetics
  • Humans
  • Interferon Regulatory Factor-1 / genetics*
  • Interferon Regulatory Factor-1 / metabolism
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Phosphatidylserines / metabolism
  • Promoter Regions, Genetic / genetics
  • Protein Binding / physiology
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins / metabolism
  • Stomach Neoplasms / genetics*
  • Stomach Neoplasms / metabolism
  • Transcriptional Activation / genetics*
  • Up-Regulation / physiology


  • Apoptosis Regulatory Proteins
  • BBC3 protein, human
  • BH3 Interacting Domain Death Agonist Protein
  • BID protein, human
  • Interferon Regulatory Factor-1
  • Mitochondrial Proteins
  • Phosphatidylserines
  • Proto-Oncogene Proteins
  • Cytochromes c
  • Caspases