ATM Phosphorylation Assay for Radiosensitivity Prediction
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Solution Overview
Problem
Current methods for predicting individual radiosensitivity to ionizing radiation are complex, time-consuming, and not easily applicable, particularly due to difficulties in analyzing radioinduced nuclear foci in lymphocyte-like cells, which hinders the assessment of tissue reactions and the determination of safe cumulative radiation doses for patients undergoing radiotherapy.
Innovation Solution
A method involving the detection and quantification of cytoplasmic and nuclear ATM protein levels in cellular samples, using mass spectrometry or ELISA tests, to assess radiosensitivity by determining the phosphorylated substrate quantity and kinase activity after irradiation, allowing for the classification of patients as radioresistant or radiosensitive based on specific thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nuclear foci analysis methods are used to predict radiosensitivity, then measurement precision is improved, but device complexity and ease of operation deteriorate due to difficulties in analyzing lymphocyte-like cells
Solution Approach 1:
The invention extracts and measures specific molecular markers (ATM protein phosphorylation levels, pATM, and gamma-H2AX) from cells as quantitative indicators of radiosensitivity. By focusing on these specific molecular features rather than overall nuclear foci analysis, the method simplifies the assessment process while maintaining predictive accuracy for tissue reactions.
Solution Approach 2:
The invention replaces complex manual nuclear foci analysis with automated biochemical assays (ELISA or Western blot) that quantify ATM phosphorylation levels. This substitution of mechanical/visual analysis with automated biochemical measurement reduces operational complexity and improves reproducibility.
2Measurement precision
If comprehensive nuclear foci analysis is performed, then measurement precision is improved, but loss of time increases due to the time-consuming nature of the procedure
Solution Approach 1:
The invention performs preliminary irradiation of patient cells with a standardized low dose (0.5-2 Gy) before conducting the biochemical assay. This preliminary action activates ATM phosphorylation in advance, allowing the subsequent ELISA or Western blot analysis to directly measure the radiation response without requiring prolonged observation periods for foci development.
Solution Approach 2:
The invention uses ELISA or Western blot techniques to create quantitative copies/measures of ATM phosphorylation levels and gamma-H2AX expression. These biochemical copies provide accurate radiosensitivity predictions without requiring direct visual analysis of nuclear foci, significantly reducing the time needed for assessment.
3Measurement precision
If lymphocyte-like cell analysis is performed, then measurement precision is improved, but ease of operation deteriorates due to technical difficulties in sample processing
Solution Approach 1:
The invention develops a universal biochemical assay protocol (ELISA or Western blot) that can measure ATM phosphorylation and gamma-H2AX levels across different cell types including lymphocytes, fibroblasts, and tumor cells. This universal approach eliminates the need for cell-type-specific analysis procedures, greatly simplifying operations while maintaining precision.
Solution Approach 2:
The invention uses biochemical markers (phosphorylated ATM, pATM, and gamma-H2AX) as intermediaries to indirectly assess radiosensitivity. Instead of directly analyzing difficult-to-process lymphocyte nuclei, the method measures these intermediary molecular markers that reflect the radiation response, simplifying the overall procedure while preserving measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a rapid and simple predictive method for individual radiosensitivity, enabling the identification of patients at risk for tissue reactions during radiotherapy, thereby optimizing treatment protocols and minimizing morbidity and mortality.
Implementation Method 1
ionizing radiation can break certain types of chemical bonds by generating free radicals (particularly by peroxidation) and other reactive species causing DNA damage
Implementation Method 2
Damage to DNA by endogenous or exogenous attacks (such as ionizing radiation and free radicals) can result in different types of DNA damage depending in particular on the energy deposited: base damage, single-strand breaks and double-strand breaks (CDB)
Implementation Method 3
two proteins of the kinase family, commonly called ATM and ATR, are involved in the detection, repair and signaling of DSBs; their action requires at least the presence of a protein known under the designation BRCA1 and an ordered cascade of phosphorylations of the different ATM substrates
Implementation Method 4
the quantity of substrate phosphorylated by the activated ATM protein... determined by mass spectrometry
Implementation Method 5
the kinase activity by quantification of the phosphorylated pATM... determined by ELISA test
Data Source
Figure 1~2
Figure 3A~3C
AI summary
A method for characterising the radiosensitivity of a cell sample of a patient to ionising radiation, said cell sample having been obtained from cells removed from a patient, the method comprising: (a) isolating nucleated target cells constituting the cell sample; (b) irradiating said cell sample before or after step (a) with an absorbed dose D of ionising radiation, (c) recovering the cytoplasmic and nuclear fractions of the cell sample; (d) determining, in the cytoplasmic and/or nuclear fractions of said cell sample: (d1) the quantity of substrate phosphorylated by activated ATM protein at at least one observation time t in the range between t1 times 1.2 and t3, preferably at at least one observation time t2 after irradiation with an absorbed dose D; and/or (d2) the kinase activity by quantifying the phosphorylated pATM at at least one observation time t selected from t= t1, t2; (e) determining at least one parameter selected from the group formed by: - the degree of severity of the post-radiotherapy tissue reaction of the patient according to the CTCAE classification, using at least the mean number pATMmax nuc(t); - the radiosensitivity of the cell sample, using at least the mean number pATMmax nuc(t); and where • t1 is a fixed value which represents the time after which the number of double-strand breaks (DSB) identified reaches a maximum in control cells from radioresistant patients; • t2 is a fixed value which represents the time after which approximately 50% of the DSB are repaired in control fibroblasts from radioresistant patients and the time after which 30% of the DSB are repaired in control lymphocytes or lymphoblasts from radioresistant patients; • t3 is a fixed value which represents z times t2, where z is between 1.1 and 8, and preferably between 1.2 and 6.