近年来，人们已经清楚，在微重力条件下，γ射线照射对细胞的细胞毒性会增加。然而，目前还没有研究重力矢量方向（而不是大小）对γ射线诱导的细胞毒性的影响。因此，在本研究中，我们对人支气管上皮BEAS-2B细胞和人肺癌A549细胞进行倒置培养，将细胞的重力矢量方向改变180°，并观察这种状态下细胞对辐射的反应。我们发现，与正常培养的细胞相比，倒置培养的细胞表现出辐射诱导的活性氧产生增加，并且抗氧化蛋白硫氧还蛋白-1 的表达减少。此外，与正常培养中受γ辐射的细胞相比，倒置培养中经γ辐射的细胞的DNA损伤反应延迟，并且未修复的DNA位点的数量增加。在倒置培养中，γ射线诱导的细胞死亡和 G2-M 期停滞的细胞数量增加，与 DNA 修复能力下降一致。我们的研究结果表明，重力矢量方向及其大小会改变细胞对辐射的反应。© 2024 作者。

In recent years, it has become clear that the cytotoxicity of γ-irradiation of cells is increased under microgravity conditions. However, there has been no study of the effect of the gravity vector direction, rather than the magnitude, on γ-ray-induced cytotoxicity. Therefore, in this study, we inverted cultures of human bronchial epithelium BEAS-2B cells and human lung cancer A549 cells in order to change the gravity vector direction by 180° with respect to the cells and observed the cellular response to radiation in this state. We found that cells in inverted culture showed increased irradiation-induced production of reactive oxygen species and decreased expression of the antioxidant protein thioredoxin-1 compared to cells in normal culture. Furthermore, the DNA damage response was delayed in γ-irradiated cells in inverted culture, and the number of unrepaired DNA sites was increased, compared to irradiated cells in normal culture. γ-Ray-induced cell death and the number of G2-M arrested cells were increased in inverted culture, in accordance with the decreased capacity for DNA repair. Our findings suggest that the gravity vector direction, as well as its magnitude, alters the cellular response to radiation.© 2024 The Authors.