Endogenous Retroelement Activation by Epigenetic Therapy Reverses the Warburg Effect and Elicits...

Area of Science:

• Oncology
• Molecular Biology
• Epigenetics

Background:

• Endogenous retroelements are epigenetically silenced in mammalian genomes.
• Anticancer therapies targeting epigenetic machinery can reactivate retroelements, inducing anti-tumor responses.
• The precise mechanisms of retroelement-induced tumor elimination are not fully understood.

Purpose of the Study:

• To elucidate the mechanisms by which epigenetically activated retroelements lead to cancer cell death.
• To investigate the role of viral sensors and metabolic reprogramming in retroelement-mediated tumor killing.
• To explore the synergistic potential of combining epigenetic therapies with BCL2 inhibitors.

Main Methods:

• Investigated the binding of retroelements to RIG-I and MDA5 viral sensors.
• Analyzed changes in intracellular energy levels (ATP hydrolysis) and metabolic pathways (glycolysis, oxidative phosphorylation).
• Examined the role of succinate dehydrogenase, oxidative stress, RIP1-mediated necroptosis, and BCL2 dependency in tumor cell death.
• Assessed synergistic responses of epigenetic inhibitors and BCL2-targeting drugs in various cancer types.

Main Results:

• Epigenetically activated retroelements bind to RIG-I and MDA5, causing ATP depletion and tumor killing independent of immune signaling.
• Energy depletion reverses the Warburg effect by shifting ATP production to mitochondrial oxidative phosphorylation.
• Hyperfunctional succinate dehydrogenase leads to oxidative stress, RIP1-mediated necroptosis, and increased BCL2 dependency.
• Epigenetic inhibitors and BCL2-targeting drugs show synergistic efficacy across multiple cancer types.

Conclusions:

• Epigenetic therapy induces viral mimicry, rewires mitochondrial metabolism, and promotes caspase-independent cell death.
• This mechanism sensitizes cancer cells to BCL2 inhibitors, offering a novel therapeutic strategy.
• The findings explain the clinical efficacy of hypomethylating agents and venetoclax in acute myeloid leukemia and suggest broader applications.