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Two distinct Fas-activated signaling pathways revealed by an antitumor drug D609

Lilin Zhang1, Shigeomi Shimizu, Yoshihide Tsujimoto

  • 1Laboratory of Molecular Genetics, Department of Post-Genomics and Diseases, Osaka University Medical School, Solution Oriented Research for Science and Technology, Japan Science and Technology Corporation, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.

Oncogene
|April 23, 2005
PubMed

Insights

The antitumor drug D609 inhibits Fas-induced apoptosis by blocking the activation of Bax and Bak, thus preventing cytochrome c release from mitochondria. D609 promotes mitochondrial resistance to apoptotic stimuli.

Area of Science:

  • Cellular biology
  • Molecular biology
  • Biochemistry

Background:

  • Death receptor-mediated apoptosis involves Bid cleavage by caspase-8, leading to mitochondrial cytochrome c release via Bax/Bak activation.
  • Understanding the precise mechanisms of apoptosis regulation is crucial for developing targeted therapies.

Purpose of the Study:

  • To investigate the mechanism by which the antitumor drug D609 inhibits Fas-induced apoptosis.
  • To elucidate the role of D609 in the apoptotic signaling pathway, particularly at the mitochondrial level.

Main Methods:

  • Utilizing cell-based assays to examine apoptosis induction and inhibition.
  • Assessing caspase-8 activation, Bid cleavage, and cytochrome c release in response to Fas activation and D609 treatment.
  • Investigating the effects of D609 on Bax and Bak activation using permeabilized cells.

Main Results:

  • D609 effectively blocks Fas-induced apoptosis without affecting caspase-8 activation or Bid cleavage.
  • D609 inhibits cytochrome c release by preventing Bax and Bak activation.
  • D609 does not protect typical type I cells (SKW6.4) from apoptosis.
  • Fas signaling involves a D609-sensitive pathway that sensitizes mitochondria to apoptosis, and D609 enhances mitochondrial resistance.

Conclusions:

  • D609 acts downstream of Bid cleavage, inhibiting apoptosis by blocking mitochondrial outer membrane permeabilization through Bax/Bak inhibition.
  • D609 reveals a novel Fas-activated, mitochondria-sensitizing pathway that is distinct from the caspase-8/Bid axis.
  • D609 demonstrates potential as a therapeutic agent by modulating apoptotic signaling at the mitochondrial level.

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