Express γ-H2AX Immunocytochemical Detection of DNA Damage

DNA can be damaged by many environmental factors including chemical agents and ionizing radiation which induce the formation of DNA double-stranded breaks (DSBs). If DSBs are not repaired in a timely fashion this may cause the disruption of genome integrity, which can result in cancer development. Typically, DSBs are followed by phosphorylation of histone protein H2AX, a member of the H2A family. Immunocytochemical detection of phosphorylated H2AX (e.g., γ-H2AX) appears to be a useful technique for assessing DNA damage. Such an assessment is easy to do by analyzing labeling for γ-H2AX under the microscope and does not require an expensive laboratory setup. Using HeLa cells treated with camptothecin as a model, we developed an easy-to-run protocol to analyze DSBs. Our protocol can be applied to testing the potency of different chemicals to induce DSBs in different types of cells and requires around 2 h to complete.