Enhancement Of Simulated Microgravity On Heavy Ion Radiation-Induced Apoptosis In Human B Lymphoblasts And Its Mechanisms

Microgravity and heavy ion radiation, widely existing in the space environment, are the main factors influencing the astronauts’health in the space flight. This study investigated the effect of heavy ion radiation on cell apoptosis under simulated microgravity and its mechanisms. The results showed that the simulated microgravity inhibited heavy ion radiation-induced cell survival and promoted its-induced apoptosis in HMy2-CIR cells. The simulated microgravity could also trigger heavy ion radiation (0.8Gy)-induced reactive oxygen speceis (ROS) generation. It was found that lipid peroxide level was very high in cells exposed to heavy ion radiation under simulated microgravity, by detecting the content of MDA. However, the content of MDA was decreased in cells pretreated with the antioxidants N-acetylcysteine (NAC) or quercetin. In order to test the effects of heavy ion radiation-induced apoptosis under simulated microgravity is associated with ROS generation, it was investigated that the cell survival and intracellular ROS production in cells pretreated with the antioxidants NAC or quercetin. And it was found that the above phenomena could be reversed by the antioxidants NAC or Quercetin. These results indicated that enhancement of simulated microgravity on heavy ion radiation-induced apoptosis was assosiated with intracellular ROS generation. Further study showed that ROS were involved in ERK1/2, MKP-1, Bcl-2and Caspase-3regulation by heavy ion radiation under simulated microgravity. The apoptosis in HMy2-CIR cells might be caused by the sustained high level activation of ERK1/2, and the expression of MKP-1and Bcl-2did not prevent this apoptotic process. The result of Caspase-3expression further confirmed simulated microgravity could promote heavy ion radiation-induced apoptosis, and this apoptosis was associated with ROS generation. In summary, simulated microgravity has additive effects on heavy ion radiation-induced HMy2-CIR cells apoptosis, and the apoptosis might be mediated by ROS-sensitive signaling pathways.