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Apoptosis, autophagy and cell cycle arrest following photodamage to mitochondrial interior

Ausra Sasnauskiene1, Jurgis Kadziauskas, Neringa Vezelyte

  • 1Department of Biochemistry and Biophysics, Vilnius University, Ciurlionio 21/27, Vilnius, Lithuania.

Apoptosis : an International Journal on Programmed Cell Death
|January 24, 2009
PubMed

Insights

Investigating oxidative stress in A431 cells revealed distinct cell death pathways. Mitochondrial-targeted photodynamic therapy (PDT) induced dose-dependent apoptosis and autophagy, differing from membrane-targeted PDT.

Area of Science:

  • Cell Biology
  • Biochemistry

Background:

  • Oxidative stress is implicated in various cellular dysfunctions.
  • Mitochondria are key organelles sensitive to oxidative damage.
  • Photodynamic therapy (PDT) is a treatment modality that uses light and photosensitizers to generate reactive oxygen species (ROS).

Purpose of the Study:

  • To investigate the distinct cellular responses to oxidative insult targeted to the mitochondrial interior versus cellular membranes.
  • To compare the effects of safranin-mediated PDT (mitochondrial-targeted) with mTHPC-mediated PDT (membrane-targeted) on A431 cells.

Main Methods:

  • A431 cells were treated with safranin-mediated photodynamic treatment (PDT) to induce ROS in mitochondria.
  • mTHPC-mediated PDT was used for comparison, targeting cellular membranes.
  • Cell death hallmarks, autophagy, apoptosis, and cell cycle progression were analyzed at different PDT doses.

Main Results:

  • Mitochondrial-targeted PDT induced a dose-dependent cell death response.
  • Low to moderate mitochondrial damage (up to CD50) resulted in enhanced autophagy and S-phase reduction, but not apoptosis.
  • Severe mitochondrial damage (beyond CD70) triggered apoptosis, cytochrome c release, caspase activation, alongside autophagy and cell cycle arrest.
  • Membrane-targeted PDT induced autophagy and apoptosis across a range of doses.

Conclusions:

  • Cellular response to oxidative stress differs significantly based on the subcellular location of ROS production.
  • Mitochondrial-targeted PDT elicits a complex, dose-dependent cell death pathway involving autophagy and apoptosis.
  • Understanding these distinct pathways is crucial for developing targeted therapeutic strategies using PDT.

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