DNA damage response in a 2D-culture model by diffusing alpha-emitters radiation therapy (Alpha-DaRT)

Area of Science:

• Radiation oncology
• Molecular biology
• Cellular biology

Background:

• Diffusing Alpha-Emitters Radiation Therapy (Alpha-DaRT) utilizes 224Ra sources to release alpha-emitting daughter atoms.
• DNA damage response (DDR) is critical for cell death induction post-irradiation.
• The temporo-spatial dynamics of DDR during Alpha-DaRT remain largely unexplored.

Purpose of the Study:

• To characterize the temporo-spatial DNA damage response (DDR) during Alpha-DaRT.
• To investigate the kinetics of DNA double-strand breaks (DSBs) and cell cycle progression under Alpha-DaRT conditions.
• To establish an experimental model for studying early-stage DDR around 224Ra sources.

Main Methods:

• Utilized HeLa cells with a Fucci cell cycle-visualizing system in 2D cultures mimicking Alpha-DaRT.
• Employed CR-39 plastic nuclear track detectors to map alpha-particle distribution.
• Correlated alpha-particle pit distribution with γH2AX staining (DSB marker).
• Performed time-lapse observations to track cell cycle kinetics at varying distances from the source.
• Quantified radiation dose and determined surviving fractions using media containing daughter nuclides.

Main Results:

• Alpha-particle pit distribution strongly correlated with γH2AX staining near the 224Ra source.
• G2 cell cycle arrest was observed more broadly 24 hours post-exposure.
• Cell cycle kinetics varied significantly with distance from the radiation source.
• Established a method to estimate radiation dose and cell survival fractions.

Conclusions:

• This study provides the first temporo-spatial characterization of early-stage DDR during Alpha-DaRT.
• The findings highlight the complex interplay between radiation source, DNA damage, and cell cycle progression.
• The developed experimental model offers a platform for further research into Alpha-DaRT mechanisms and optimization.