目的：本研究旨在探讨融合抗氧化酶GST-SOD1-X-R9（GS1XR）对正常鼻咽上皮细胞NP69的放射防护作用及其可 能的机制。方法：培养NP69细胞，分为空白对照（Untr）组、EGFP-GS1组、EGFP-GS1R组和EGFP-GS1XR组，检测0.5 mg/mL不 同融合抗氧化酶的跨膜效应。用CCK-8法测定3种融合抗氧化酶在0～1 mg/mL质量浓度范围内的细胞毒性。以DCFH-DA荧 光探针测定0～6 Gy X射线和不同剂量（0～1 mg/mL）GS1XR对NP69细胞内ROS水平的影响。进一步实验将NP69细胞分为 Untr组、4 Gy X线单纯照射Ctrl组和照射前分别预处理GS1、GS1R、GS1XR及阿米福汀（AMFT，4 μg/mL）组，检测细胞内ROS水 平，流式细胞术检测细胞的凋亡率，用WB法检测Nrf2入核量、抗氧化基因GCLC以及抗凋亡因子Bcl-2和凋亡因子BAX的表达。 结果：实验结果显示，EGFP-GS1不具备跨膜能力，而EGFP-GS1R和EGFP-GS1XR能够有效跨膜进入NP69细胞（P < 0.000 1）。 经24 h处理后，3种融合抗氧化酶均使细胞活力保持在80%以上，其中GS1XR处理组的细胞活力维持在100%以上。4 Gy X射线 照射显著增加细胞内ROS水平（P < 0.01），GS1XR以剂量依赖方式清除辐射诱导的ROS。与Ctrl组相比，GS1XR显著降低受照 细胞内的ROS水平（P < 0.05），促进Nrf2的入核（P < 0.01），上调抗氧化基因GCLC（P < 0.000 1），降低细胞的凋亡率（P < 0.000 1） 和抗凋亡因子Bcl-2（P < 0.001）的表达，并下调促凋亡因子BAX的表达（P < 0.05）。GS1XR的整体保护作用与GS1R相似，且与 阿米福汀效果相当。结论：融合抗氧化酶GS1XR对NP69细胞具有显著的放射防护效应，其机制可能与其可进入细胞清除受照细 胞内ROS，激活Nrf2信号通路，并调节Bcl-2和BAX的表达有关，GS1XR有望成为一种新型的放射防护剂。

Objective: To investigate the radioprotective effects of the fusion antioxidant enzyme GST-SOD1-X-R9 (GS1XR) on normal nasopharyngeal epithelial cells (NP69) and its potential mechanisms. Methods: NP69 cells were cultured and divided into the following groups: untreated control (Untr) group, EGFP-GS1 group, EGFP-GS1R group, and EGFP-GS1XR group. The transmembrane effect of different fusion antioxidant enzymes was evaluated at a concentration of 0.5 mg/mL. The cytotoxicity of the three enzymes within a concentration range of 0 to 1 mg/mL was determined using the CCK-8 assay. ROS levels in NP69 cells were measured using a DCFH-DA fluorescent probe following exposure to 0～6 Gy X-ray and varying doses (0～1 mg/mL) of GS1XR. In further experiments, NP69 cells were divided into blank control (Untr) group, 4 Gy X-ray only group (Ctrl), and groups pre-treated with GS1, GS1R, GS1XR, or Amifostine (AMFT, 4 μg/mL) before X-ray exposure. ROS levels, apoptosis rate, Nrf2 nuclear translocation, and expression of antioxidant gene GCLC, anti-apoptotic factor Bcl-2, and pro-apoptotic factor BAX were evaluated using flow cytometry and WB analysis. Results: EGFP-GS1 lacked transmembrane ability, whereas EGFP-GS1R and EGFP-GS1XR efficiently crossed the NP69 cell membrane (P < 0.000 1). After 24 hours of treatment, all three fusion antioxidant enzymes maintained cell viability above 80%, with the GS1XR-treated group maintaining cell viability above 100%. Exposure to 4 Gy X-ray significantly increased intracellular ROS levels (P < 0.01), while GS1XR effectively reduced radiation-induced ROS in a dose-dependent manner. Compared to the Ctrl group, GS1XR significantly decreased intracellular ROS levels (P < 0.05), promoted Nrf2 nuclear translocation (P < 0.01), upregulated the expression of antioxidant gene GCLC (P < 0.000 1), and reduced the apoptosis rate (P < 0.000 1). Additionally, it increased the expression of anti-apoptotic factor Bcl-2 (P < 0.001) and downregulated pro-apoptotic factor BAX (P < 0.05). The overall protective effects of GS1XR were similar to those of GS1R and comparable to the effects of Amifostine. Conclusion: The fusion antioxidant enzyme GS1XR exhibits significant radioprotective effects on NP69 cells, likely through its ability to enter cells, eliminate radiation-induced ROS, activate the Nrf2 signaling pathway, and regulate the expression of Bcl-2 and BAX. GS1XR shows potential as a novel radioprotective agent.

国家自然科学基金（No. 81974482）；福建省科技创新联合资金项目（No. 2021Y9191）；福建省自然科学基金（No. 2023J011238）