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Induction of caspase-dependent and -independent apoptosis in response to methionine restriction

Shan Lu1, Sara M Hoestje, Eugene Choo

  • 1Department of Medicine, Baylor College of Medicine and VA Medical Center, Houston, TX 77030, USA.

International Journal of Oncology
|January 16, 2003
PubMed

Insights

Methionine restriction induces programmed cell death in tumor cells via mitochondria-dependent pathways. This process involves caspase-dependent and -independent cell death, highlighting a potential therapeutic vulnerability in cancer.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Tumor cells exhibit heightened sensitivity to methionine restriction (methionine auxotrophy) compared to normal tissues.
  • Previous research indicates methionine restriction triggers tumor cell growth arrest and apoptosis.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying apoptosis induced by methionine restriction.
  • To elucidate the role of mitochondria and caspases in this process.

Main Methods:

  • Assessing DNA fragmentation and cytochrome c release in response to methionine restriction.
  • Analyzing caspase activation and cleavage of key apoptotic proteins (BID, Bcl-2).
  • Comparing cell death pathways (caspase-dependent vs. caspase-independent) in different cell lines (PC3, Hela).

Main Results:

  • Methionine restriction induced DNA fragmentation and cytochrome c release in PC3 and Hela cells.
  • Hela cells showed caspase activation, while PC3 cells exhibited caspase-independent cell death.
  • Cleavage of BID and reduced Bcl-2 levels were observed in both cell lines, suggesting mitochondrial involvement.

Conclusions:

  • Apoptosis induced by methionine restriction is primarily mitochondria-dependent.
  • Methionine restriction triggers distinct cell death pathways (caspase-dependent in Hela, independent in PC3).
  • BID cleavage and Bcl-2 downregulation are key events mediating cytochrome c release and apoptosis.

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