Modulation of therapy-induced senescence by reactive lipid aldehydes

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• Unrepaired chromosomal damage is considered the primary driver of accelerated senescence in cancer cells post-radiation or chemotherapy.
• Etoposide, a senescence inducer, causes DNA damage via topoisomerase II inhibition and generates reactive oxygen species (ROS).

Purpose of the Study:

• To investigate the roles of DNA damage and oxidative stress in therapy-induced senescence.
• To screen redox-active agents for their ability to enhance radiation-induced senescence.

Main Methods:

• Development of a quantitative flow cytometric assay for senescence.
• Screening of 36 redox-active agents as enhancers of a low-dose radiation treatment.
• Measurement of reactive oxygen species (ROS) and lipid peroxidation levels.

Main Results:

• Senescence induction did not correlate with total ROS levels.
• Effective enhancers, including etoposide and other topoisomerase inhibitors, induced significant lipid peroxidation.
• The lipid peroxidation product 4-hydroxy-2-nonenal (4-HNE) could induce senescence in irradiated cells.
• Hydralazine, an aldehyde scavenger, inhibited the senescence-inducing effects of etoposide and other agents.

Conclusions:

• Lipid peroxidation, rather than total ROS, is a key mediator of therapy-induced senescence.
• Reactive aldehydes resulting from lipid peroxidation contribute significantly to senescence.
• Lipid peroxidation potentiates DNA damage, driving senescence in response to radiation and chemotherapy.