Inhibition of the Histone H3K27 Demethylase UTX Enhances Tumor Cell Radiosensitivity.

The processes mediating the repair of DNA double-strand breaks (DSB) are critical determinants of radiosensitivity and provide a source of potential targets for tumor radiosensitization. Among the events required for efficient DSB repair are a variety of post-translational histone modifications, including methylation. Because trimethylation of histone H3 on lysine 27 (H3K27me3) has been associated with chromatin condensation, which can influence DSB repair, we determined the effects of radiation on H3K27me3 levels in tumor and normal cell lines.