Flavonoids from Rosa roxburghii Tratt prevent reactive oxygen species-mediated DNA damage in thymus cells both combined with and without PARP-1 expression after exposure to radiation in vivo

This study aimed to evaluate the role of FRT in ROS/DNA regulation with or without PARP-1 in radiation-injured thymus cells. The administration of FRT to PARP-1-/- (KO) mice demonstrated that FRT significantly increased the viability of thymus cells and decreased their rate of apoptosis through PARP-1. Radiation increased the levels of ROS, γ-H2AX and 53BP1, and induced DNA double strand breaks. Compared with wild type (WT) mice, levels of ROS, γ-H2AX and 53BP1 in KO mice were much less elevated. The FRT treatment groups also showed little reduction in these indicators in KO mice compared with WT mice. The results of the KO mice study indicated that FRT reduced ROS activation through inhibition of PARP-1. Furthermore, FRT reduced the concentrations of γ-H2AX by decreasing ROS activation. However, we found that FRT did not regulate 53BP1, a marker of DNA damage, because of its elimination of ROS. Levels of apoptosis-inducing factor (AIF), exhibited no significant difference after irradiation in KO mice. To summarize, ROS suppression by PARP-1 knockout in KO mice highlights potential therapeutic target either by PARP-1 inhibition combined with radiation or by treatment with a drug therapy alone. AIF-induced apoptosis could not be activated in KO mice.