Related Experiment Video
Updated: Jun 3, 2026
Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors
Published on: July 17, 2020
A minimally invasive assay for individual assessment of the ATM/CHEK2/p53 pathway activity
Sylwia Kabacik1, Ana Ortega-Molina, Alejo Efeyan
1Biological Effects Department, Centre for Radiation Chemical and Environmental Hazards, Health Protection Agency, Didcot, Oxfordshire, UK.
Abstract:
Ionizing radiation induces DNA Double-Strand Breaks (DSBs) which activate the ATM/CHEK2/p53 pathway leading to cell cycle arrest and apoptosis through transcription of genes including CDKN1A (p21) and BBC3 (PUMA). This pathway prevents genomic instability and tumorigenesis as demonstrated in heritable syndromes [e.g. Ataxia Telangiectasia (AT); Li-Fraumeni syndrome (LFS)]. Here, a simple assay based on gene expression in peripheral blood to measure accurately ATM/CHEK2/p53 pathway activity is described. The expression of p21, Puma and Sesn2 was determined in blood from mice with different gene copy numbers of Atm, Trp53 (p53), Chek2 or Arf and in human blood and mitogen stimulated T-lymphocyte (MSTL) cultures from AT, AT carriers, LFS patients, and controls, both before and after ex vivo ionizing irradiation. Mouse Atm/Chek2/p53 activity was highly dependent on the copy number of each gene except Arf. In human MSTL, an AT case, AT carriers and LFS patients showed responses distinct from healthy donors. The relationship between gene copy number and transcriptional induction upon radiation was linear for p21 and Puma and correlated well with cancer incidence in p53 variant mice. This reliable blood test provides an assay to determine ATM/CHEK2/p53 pathway activity and demonstrates the feasibility of assessing the activity of this essential cancer protection pathway in simple assays. These findings may have implications for the individualized prediction of cancer susceptibility.
Insights
A new blood test accurately measures the ATM/CHEK2/p53 pathway activity, crucial for preventing cancer. This assay can assess DNA damage response and may help predict individual cancer susceptibility.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- DNA Double-Strand Breaks (DSBs) activate the ATM/CHEK2/p53 pathway, essential for cell cycle arrest and apoptosis.
- Dysfunction in this pathway is linked to genomic instability and hereditary cancer syndromes like Ataxia Telangiectasia (AT) and Li-Fraumeni syndrome (LFS).
Purpose of the Study:
- To develop a simple peripheral blood assay for accurately measuring ATM/CHEK2/p53 pathway activity.
- To validate this assay in mouse models and human samples, including patients with AT and LFS.
Main Methods:
- Gene expression analysis of CDKN1A (p21), BBC3 (PUMA), and SESN2 in peripheral blood.
- Experiments conducted on mice with varying gene copy numbers of Atm, Trp53 (p53), Chek2, and Arf.
- Analysis of human mitogen-stimulated T-lymphocyte (MSTL) cultures from AT patients, carriers, LFS patients, and controls, with and without ex vivo irradiation.
Main Results:
- Mouse ATM/CHEK2/p53 pathway activity correlated linearly with gene copy number for Atm, Trp53, and Chek2, but not Arf.
- Human MSTL cultures from AT cases, carriers, and LFS patients exhibited distinct responses to irradiation compared to healthy donors.
- Transcriptional induction of p21 and PUMA showed a linear relationship with gene copy number and correlated with cancer incidence in p53 variant mice.
Conclusions:
- A reliable blood test to assess ATM/CHEK2/p53 pathway activity has been developed.
- This assay demonstrates the feasibility of evaluating this critical cancer protection pathway using simple blood tests.
- The findings suggest potential applications in individualized prediction of cancer susceptibility.
