Comparative Study of Histone Deacetylase Inhibitors for Radiation Protection Using Survival Outcomes in a Mouse Model.

Histone deacetylases (HDACs) regulate chromatin structure and gene expression, and their inhibition has been proposed as a radioprotective strategy. However, few studies have compared multiple HDAC inhibitors (HDACis) under identical conditions. This study evaluated the efficacy of seven HDACis in a mouse total body irradiation (TBI) model. Male ICR mice received 7.5 Gy TBI followed by a single administration of valproic acid (VPA; 300 or 600 mg/kg), sodium butyrate (NaB; 500 or 1000 mg/kg), trichostatin A (TSA; 0.5 or 1.0 mg/kg), vorinostat (10 or 50 mg/kg), panobinostat (25 or 50 mg/kg), givinostat (5 or 10 mg/kg), or entinostat (25 or 50 mg/kg). Survival was monitored for 20 d. Only VPA at 600 mg/kg significantly improved survival compared with vehicle (overall p = 0.00241; p = 0.0039 vs. vehicle), while all other HDACis showed no significant benefit. VPA's efficacy may reflect a combination of effects on DNA repair, inflammation, and redox regulation rather than HDAC inhibition alone. These findings suggest VPA to be a promising candidate for radioprotection and emphasize the need for further studies to optimize dosing and explore underlying mechanisms.