How histone modifications influence cellular radiosensitivity: Pharmaceutically targeting epigenetic regulators as a promising avenue to overcome radioresistance

Cancer remains the leading cause of mortality worldwide. Radiotherapy (RT), a cornerstone of oncological treatment for over a century, has achieved great success in various cancers. However, radioresistance remains the primary factor leading to the failure of radiotherapy. Histone modifications in cancer cells are known to play a pivotal role in regulating radiosensitivity by modulating chromatin structure, either by loosening or tightening it. Here, we provide a comprehensive summary of the link between aberrant histone modifications and radiation resistance across various cancer and normal tissue cells. Furthermore, we discuss the regulatory mechanisms of histone modifications and the enzymes on the recruitment of proteins that recognize histone modifications. Consequently, these processes substantially affect the radiosensitivity of tumors. In addition to cancer cells, we highlight the intricate interplay between histone modification and radiosensitivity, both within and beyond the cancer cells. Meanwhile, various drugs targeting histone modifications emerge as a promising therapeutic strategy to overcome radioresistance of tumors as well as radioprotection. The combination of histone modification inhibitors with radiotherapy presents a novel approach to enhance cancer treatment outcomes in clinical practice. Nevertheless, the underlying mechanisms through which histone modifications influence cancer radiosen-sitivity require further elucidation to identify novel targets for radiotherapeutic intervention.