Valproic acid, a histone deacetylase inhibitor, enhances radiosensitivity in breast cancer cell line

Purpose: Valproic acid (VPA) is used mainly for the treatment of epilepsy and other seizure disorders, however, it is known to be one of histone deacetylase (HDAC) inhibitors. HDACIs have represented roles in radiation-sensitizing of cancer cells. This study is aimed to study to evaluate the radiosensitizing capability of VPA in MCF-7 breast cancer cell line. Materials and Methods: Cell viability and apoptosis were assayed using MTT and TUNEL assays, respectively and caspase-8 and caspase-9 activities were measured by commercially available kits. Results: Our finding showed that pre treatment of cells with VPA, notably enhanced apoptotic cell death in MCF-7 cell line. Our results showed that VPA sensitizes cancer cells against radiation. Conclusion: Valproic acid could be a beneficial radio-sensitizer in breast cancer radiotherapy.