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A Synthetic Lethal Interaction between Glutathione Synthesis and Mitochondrial Reactive Oxygen Species Provides a
Daniel J Garama1, Tiffany J Harris1, Christine L White1
1STAT Cancer Biology Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, Victoria, Australia Monash University, Clayton, Victoria, Australia.
Abstract:
Increased production of mitochondrion-derived reactive oxygen species (ROS) is characteristic of a metabolic shift observed during malignant transformation. While the exact sources and roles of ROS in tumorigenesis remain to be defined, it has become clear that maintaining redox balance is critical for cancer cell proliferation and survival and, as such, may represent a vulnerability that can be exploited therapeutically. STAT3, a latent cytosolic transcription factor activated by diverse cytokines and growth factors, has been shown to exhibit an additional, nontranscriptional function in mitochondria, including modulation of electron transport chain activity. In particular, malignant transformation by Ras oncogenes exploits mitochondrial STAT3 functions. We used mass spectrometry-based metabolomics profiling to explore the biochemical basis for the STAT3 dependence of Ras transformation. We identified the gamma-glutamyl cycle, the production of glutathione, and the regulation of ROS as a mitochondrion-STAT3-dependent pathway in Ras-transformed cells. Experimental inhibition of key enzymes in the glutathione cycle resulted in the depletion of glutathione, accumulation of ROS, oxidative DNA damage, and cell death in an oncogenic Ras- and mitochondrial STAT3-dependent manner. These data uncover a synthetic lethal interaction involving glutathione production and mitochondrial ROS regulation in Ras-transformed cells that is governed by mitochondrial STAT3 and might be exploited therapeutically.
Insights
Cancer cells rely on mitochondrial STAT3 to regulate glutathione production and reactive oxygen species (ROS). Inhibiting this pathway causes oxidative stress and cell death, offering a potential therapeutic strategy.
Area of Science:
- Cellular metabolism and redox biology
- Cancer cell signaling and mitochondrial function
- Oncogene-induced transformation
Background:
- Malignant transformation involves increased mitochondrial reactive oxygen species (ROS) production.
- Redox balance is crucial for cancer cell survival and proliferation, presenting a therapeutic vulnerability.
- STAT3, a transcription factor, has non-transcriptional roles in mitochondria, influencing electron transport chain activity and exploited by Ras oncogenes.
Purpose of the Study:
- To investigate the biochemical mechanisms underlying STAT3 dependence in Ras-transformed cells.
- To identify the specific metabolic pathways regulated by mitochondrial STAT3 in cancer.
- To explore the therapeutic potential of targeting this pathway.
Main Methods:
- Mass spectrometry-based metabolomics profiling of Ras-transformed cells.
- Experimental inhibition of key enzymes in the gamma-glutamyl/glutathione cycle.
- Assessment of reactive oxygen species (ROS) levels, glutathione production, and oxidative DNA damage.
Main Results:
- Identified a mitochondrion-STAT3-dependent pathway involving the gamma-glutamyl cycle, glutathione production, and ROS regulation in Ras-transformed cells.
- Inhibition of glutathione synthesis enzymes led to glutathione depletion and ROS accumulation.
- Observed oncogenic Ras- and mitochondrial STAT3-dependent oxidative DNA damage and cell death.
Conclusions:
- Uncovered a synthetic lethal interaction between glutathione production and mitochondrial ROS regulation in Ras-transformed cells.
- Mitochondrial STAT3 governs this pathway, highlighting its critical role in cancer cell survival.
- This pathway represents a potential therapeutic target for Ras-driven cancers.
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