TRAIL treatment provokes mutations in surviving cells.

Area of Science:

• Cellular Biology
• Molecular Oncology
• Cancer Therapeutics

Background:

• Chemotherapy and radiotherapy induce DNA damage and apoptosis, but can lead to treatment resistance and secondary malignancies.
• Death ligand-based therapies (e.g., TRAIL) activate extrinsic apoptosis pathways, potentially bypassing resistance mechanisms.
• It was hypothesized that extrinsic apoptosis pathways might spare surviving cells from genetic damage.

Purpose of the Study:

• To investigate whether death ligand-based therapies, such as TRAIL, cause genetic damage in surviving cancer cells.
• To determine the mechanisms underlying TRAIL-induced mutagenesis in non-malignant cells.

Main Methods:

• Treatment of cells with sub-lethal concentrations of TRAIL or FasL.
• Assessment of caspase activation and DNA damage.
• Genetic manipulation including overexpression of caspase-8 inhibitors (crmA) and silencing of caspase-8.
• Downregulation of caspase-activated DNAse (CAD)/DNA fragmentation factor 40 (DFF40).

Main Results:

• Sub-lethal concentrations of TRAIL and FasL induced mutagenesis in surviving cells.
• Mutagenesis was dependent on active caspases, specifically caspase-8.
• Inhibition of caspase-8 or downregulation of CAD/DFF40 prevented TRAIL-induced DNA damage and mutagenesis.
• Surviving cells sustained DNA damage despite death ligands not primarily targeting DNA.

Conclusions:

• Death ligand-based therapies, contrary to initial hypotheses, can be mutagenic in surviving cells.
• The extrinsic apoptosis pathway, while not directly damaging DNA, can trigger downstream events leading to genetic alterations.
• Understanding these mechanisms is crucial for evaluating the safety and efficacy of death ligand therapies in cancer treatment.