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Author Spotlight: Transmitochondrial Cybrid Generation Using Cancer Cell Lines
Published on: March 17, 2023
Energetic metabolic reprogramming in Jurkat DFF40-deficient cancer cells
Merve Kulbay1,2, Bruno Johnson1, Guillaume Ricaud1
1INRS-Centre Armand-Frappier Santé Biotechnologie, 531 Boul. des Prairies, Laval, QC, H7V 1B7, Canada.
Abstract:
DNA fragmentation factor 40 (DFF40), or the caspase-activated DNase (CAD), is an endonuclease specific for double-stranded DNA. Alterations in its function and expression have been linked to apoptosis resistance, a mechanism likely used by cancer cells. However, how the DFF40-related apoptosis resistance pathway occurs remains unclear. Here, we sought to determine if DFF40 expression could be linked to cell metabolism through the regulation of mitochondrial integrity and function. We demonstrated that DFF40-deficient cells are more resistant to staurosporine and tributyltin (TBT)-induced apoptosis, and express higher levels of Mcl-1 at basal state. Treatment with TBT induces higher Bcl-2 and caspase-9 mRNA transcripts in DFF40 KO Jurkat cells, as well as enhanced Bcl-2 phosphorylation. A loss of DFF40 expression induces a higher mitochondrial mass, mtDNA copy number, mitochondrial membrane potential, and glycolysis rates in resting T cells. DFF40-deficient cells exhibit the Warburg effect phenotype, where they rely significantly more on glycolysis than oxidative phosphorylation and have a higher proliferative state, demonstrated by a higher Ki-67 transcription factor expression and AKT phosphorylation. Finally, we demonstrated with cell fractioning that DFF40 can translocate to the mitochondria following apoptosis induction. Our study reveals that DFF40 may act as a regulator of mitochondria during cell death and its loss could compromise mitochondrial integrity and cause an energetic reprogramming in pathologies such as cancer.
Insights
Loss of DNA fragmentation factor 40 (DFF40) enhances resistance to apoptosis by altering mitochondrial function and promoting glycolysis, potentially contributing to cancer development.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- DNA fragmentation factor 40 (DFF40), also known as caspase-activated DNase (CAD), is an endonuclease implicated in apoptosis.
- Altered DFF40 function and expression are linked to apoptosis resistance, a common hallmark of cancer cells.
- The precise mechanisms underlying DFF40-mediated apoptosis resistance and its connection to cell metabolism remain largely unknown.
Purpose of the Study:
- To investigate the potential link between DFF40 expression and cell metabolism.
- To determine if DFF40 regulates mitochondrial integrity and function.
- To elucidate the role of DFF40 in apoptosis resistance and its implications for cancer.
Main Methods:
- Generated DFF40-deficient (KO) cells and compared them to wild-type cells.
- Assessed apoptosis resistance using staurosporine and tributyltin (TBT) treatments.
- Analyzed mitochondrial mass, membrane potential, glycolysis rates, and key protein/gene expression (Mcl-1, Bcl-2, caspase-9, Ki-67, AKT).
- Utilized cell fractionation to determine DFF40 subcellular localization upon apoptosis induction.
Main Results:
- DFF40-deficient cells exhibited increased resistance to apoptosis and higher basal Mcl-1 levels.
- TBT treatment led to elevated Bcl-2 and caspase-9 mRNA, and enhanced Bcl-2 phosphorylation in DFF40 KO cells.
- Loss of DFF40 resulted in increased mitochondrial mass, mtDNA copy number, membrane potential, and glycolysis rates.
- DFF40-deficient cells displayed the Warburg effect phenotype, increased proliferation (Ki-67), and elevated AKT phosphorylation.
- DFF40 was observed to translocate to mitochondria following apoptosis induction.
Conclusions:
- DFF40 plays a role in regulating mitochondrial integrity and function during apoptosis.
- Loss of DFF40 compromises mitochondrial integrity, leading to metabolic reprogramming.
- DFF40 deficiency promotes a glycolytic phenotype and enhanced proliferation, potentially contributing to cancer pathogenesis.
- DFF40's translocation to mitochondria suggests a direct role in cell death pathways.
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