Validation of a Flow Cytometry-based Detection of γ-H2AX, to Measure DNA Damage for Clinical Applications

Background: The nucleosomal histone protein H2AX is specifically phosphorylated (gamma-H2AX) adjacent to DNA double-strand breaks (DSBs) and is used for quantifying DSBs. Many chemotherapies and ionizing radiation (IR) used in cancer treatment result in DSBs. Therefore, gamma-H2AX has a significant potential as a biomarker in evaluating patient sensitivity and responsiveness to IR and chemotherapy. Methods: Here, we report a flow cytometry-based quantification of gamma-H2AX (FCM-gamma-H2AX assay) customized for clinical practice. Results: We validated that our method is able to detect DNA damage in peripheral blood mononuclear cells (PBMCs) treated with DSB inducing agents. The method also detected the DNA repair deficiency in PBMCs treated with DNA repair inhibitors, as well as the deficiency in DNA repair signaling in PBMCs from two ataxia telangiectasia patients. Conclusions: The FCM-gamma-H2AX assay has sufficient analytical sensitivity and precision to measure levels of DNA damage and DNA repair for clinical purposes. (C) 2016 International Clinical Cytometry Society