Related Experiment Video
Updated: Jun 5, 2026

Cell Cycle-specific Measurement of γH2AX and Apoptosis After Genotoxic Stress by Flow Cytometry
Published on: September 1, 2019
RBE of α-particles from (211)At for complex DNA damage and cell survival in relation to cell cycle position
Kristina Claesson1, Karin Magnander, Helena Kahu
1Department of Oncology, Institute of Clinical Sciences, University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden.
Purpose:
To investigate cell cycle effects and relative biological effectiveness (RBE) of α-particles from the clinically relevant radionuclide Astatine-211 ((211)At), using X-rays as reference radiation. Double-strand breaks (DSB), non-DSB clusters containing oxidised purines and clonogenic survival were investigated.
Materials And Methods:
Asynchronous V79-379A fibroblasts or cells synchronised with mimosine in G1, early, mid and late S phase or in mitosis were irradiated with X-rays (100 kV(p)) or (211)At (mean linear energy transfer (LET) 110 keV/μm). Induction of DSB and clusters was determined using pulsed-field gel electrophoresis with fragment analysis. Cell survival was obtained with the clonogenic assay.
Results:
In asynchronous cells RBE for DSB- and cluster-induction was 3.5 and 0.59, respectively. RBE for 37% cell survival was 8.6. In different cell cycle phases RBE varied from 1.8-3.9 for DSB and 3.1-7.9 for 37% survival (survival at 2 Gy was 6.9-38 times lower after α-irradiation). (211)At induced 6 times more DSB and X-rays induced 11 times more DSB in mitotic cells with highly compacted chromatin relative G1.
Conclusions:
The radio-response is cell cycle dependent and differs between proliferating and non-cycling cells for both low- and high-LET radiation, resulting in a variation in RBE of α-particles between 1.8 and 8.6.
Related Concept Videos
DNA Damage Can Stall the Cell Cycle
DNA Damage can Stall the Cell Cycle
Nucleotide Excision Repair
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Nucleotide Excision Repair
Negative Regulator Molecules
Long-patch Base Excision Repair

