Observation of Histone H2AX Phosphorylation by Radiation-Induced Bystander Response Using Titanium Characteristic...

Area of Science:

• Radiation biology
• Cellular signaling
• Biophysics

Background:

• Radiation-induced bystander response (RIBR) involves non-targeted cells responding to signals from irradiated cells.
• Previous X-ray microbeams used low-energy X-rays, limiting studies on 3D tissues.
• Understanding RIBR mechanisms is crucial for radiation safety and therapy.

Purpose of the Study:

• To upgrade an X-ray microbeam system for higher energy X-rays (Ti K X-rays) capable of irradiating 3D tissues.
• To investigate the induction and quantitative evaluation of RIBR using a novel method.
• To assess the non-targeted effects of precise irradiation on cellular responses.

Main Methods:

• Upgraded microbeam X-ray cell irradiation system using high-energy titanium characteristic X-rays (Ti K X-rays).
• Precise irradiation of HeLa cell nuclei within 3D cultured tissues.
• Quantitative evaluation of bystander cells via phosphorylated histone H2AX (γ-H2AX) fluorescence intensity.

Main Results:

• Pan-nuclear γ-H2AX induction observed in non-irradiated bystander cells 180 and 360 minutes post-irradiation.
• Significant increase in bystander cell percentage: 23.2% ± 3.2% at 180 min and 29.3% ± 3.5% at 360 min.
• Established a reliable method for quantifying RIBR using γ-H2AX as a biomarker.

Conclusions:

• The upgraded Ti K X-ray microbeam system enables precise irradiation of 3D tissues, facilitating RIBR studies.
• γ-H2AX is a validated indicator for quantifying radiation-induced bystander effects.
• Findings contribute to understanding non-targeted effects and cell competition in radiation biology.