Development of a High-Content Screening Method for Chemicals Modulating DNA Damage Response

The cellular response to DNA damage is emerging as a promising target for cancer therapy. In the present study, the authors exploited the relationship between the level of the phosphorylated form of histone H2AX (gamma H2AX) and the extent of DNA damage and developed a quantitative, cell-based, high-content screening system for measuring the DNA damage response (DDR). In this system, the authors quantified the level of gamma H2AX by measuring DNA damage-induced gamma H2AX nuclear foci using an automated cell imager. They found that the total area of gamma H2AX foci per cell exhibited a good correlation with the concentration of DNA damage-inducing agents, including etoposide. The effects of 2 well-known inhibitors of DNA damage could be quantified using this system, suggesting the suitability of the gamma H2AX-foci quantification method for large-scale screening applications. This was confirmed by using this method to screen a chemical library; the resulting "hits" included compounds that inhibited early signaling events in DDR, as well those that inhibited subsequent DNA damage repair processes. Overall, this gamma H2AX foci-measuring system may be an effective screening method for identifying DNA damage response inhibitors that could eventually be used to develop novel anticancer drugs. (Journal of Biomolecular Screening 2011;16:259-265)