Department of Oncology, the Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China.
Department of Respiratory, Chongqing Three Gorges Central Hospital, Chongqing 404000, China.
Acta Biochim Biophys Sin (Shanghai). 2020 Apr 20;52(4):439-445. doi: 10.1093/abbs/gmaa013.
Hyperthermia, particularly in combination with chemoradiotherapy, is widely used to treat various cancers. However, hyperthermia treatment is often insufficient due to thermo-tolerance. To date, the detailed mechanism underlying thermo-tolerance has not been clarified. The nuclear factor erythroid 2-related factor 2 (Nrf2)/ antioxidant response element (ARE) pathway is an important cellular cytoprotective defense system that is activated by various stresses. In this study, using immunocytochemistry and western blot analysis, we demonstrated that heat stress induced Nrf2/ARE activation through the nuclear translocation of Nrf2 in non-small cell lung cancer cells. Luciferase activity was also increased. Additionally, antioxidant enzymes were increased through Nrf2 activation after heat stress. Transfection of lung cancer cells with siRNA directed against Nrf2 increased heat cytotoxicity and cell apoptosis. Heat stress could induce reactive oxygen species (ROS) accumulation, while the antioxidant NAC obviously reduced cell apoptosis ratio, indicating that heat stress induced cell apoptosis in a ROS-dependent manner. Knockdown of Nrf2 led to an abnormal elevation of ROS, and the antioxidant NAC could increase Nrf2 activation, indicating that ROS and Nrf2 act within a negative feedback loop. Taken together, these results demonstrated that Nrf2 pathway is important for maintaining resistance to heat stress, and we postulated that Nrf2 may represent a potential therapeutic target for hyperthermia in lung cancer.
热疗，特别是联合放化疗，被广泛用于治疗各种癌症。然而，由于热耐受，热疗往往不够充分。迄今为止，热耐受的详细机制尚未阐明。核因子红细胞 2 相关因子 2（Nrf2）/抗氧化反应元件（ARE）通路是一种重要的细胞保护防御系统，可被各种应激激活。在本研究中，我们通过免疫细胞化学和 Western blot 分析证实，热应激通过 Nrf2 在非小细胞肺癌细胞中的核转位诱导 Nrf2/ARE 激活。荧光素酶活性也增加了。此外，热应激后通过 Nrf2 激活增加了抗氧化酶。用 Nrf2 的 siRNA 转染肺癌细胞增加了热细胞毒性和细胞凋亡。热应激可诱导活性氧（ROS）积累，而抗氧化剂 NAC 明显降低细胞凋亡率，表明热应激以 ROS 依赖的方式诱导细胞凋亡。Nrf2 的敲低导致 ROS 的异常升高，而抗氧化剂 NAC 可以增加 Nrf2 的激活，表明 ROS 和 Nrf2 处于负反馈循环中。综上所述，这些结果表明 Nrf2 通路对于维持对热应激的抗性非常重要，我们推测 Nrf2 可能代表肺癌热疗的潜在治疗靶点。
