Activation of DNA Damage Signaling Components by Diagnostic Computed Tomography (CT) Scans Detected in Patient Samples Using an Electrochemiluminescence-Based Assay Platform

Technologiesthat measure activation of components of the DNA damage response (DDR) haveapplications in exposure assessment and personalized medicine. The DDR andassociated DNA repair pathways encompass hundreds of proteins, making detailedmeasurement of activation technically challenging and laborious. The purpose ofour study was to develop protein-specific assays for certain DDR components on a high-throughputelectrochemiluminescence (ECL)-based platform. We developed five working assaypairs for ataxia telangiectasia mutated (ATM), checkpoint kinase 2 (CHK2), phosphorylated-ATM S1981, phosphorylated-CHK2 T68 and phosphorylated-tumorprotein p53 (p53) S15. We validated the ECL results against traditional immunoblot and γ-H2AXfoci measures in cell and cancer models. In an effort to test the ECL-basedtechnology in a clinical setting, we utilized peripheral blood mononuclearcells (PBMCs) from patients undergoing computed tomography (CT) scans. CT scans represent both a valuable medical imagingdiagnostic and a controlled environmental exposure to ionizing radiation forresearch studies, as they deliver ~2 to 31 millisieverts (mSv) and are known toactivate DDR components. In this study, we show that ECL-based technology canmeasure the basal and damage-induced levels of DDR components in patient PBMCsamples. Using a blinded study design and patient matched pre- and post CT scan samples, we show that ECL-derived data canconsistently (94% of the time, 15/16 patients) identify PBMCs that have beenexposed to low dose ionizing radiation associated with CT scans. Ultimately, the results of our pilot clinicalstudy support the idea that ECL-based technology is applicable for use inclinical and population cohorts that study components of the DDR.