Gain of Nrf2 Function in Non-Small-Cell Lung Cancer Cells Confers Radioresistance
Gain of Nrf2 Function in Non-Small-Cell Lung Cancer Cells Confers Radioresistance
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DOI：
10.1089/ars.2010.3219
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发表时间：
2010-12-01
影响因子：
6.6
通讯作者：
Biswal, Shyam
中科院分区：
文献类型：
--
作者：
Singh, Anju;Bodas, Manish;Biswal, Shyam
核因子E2相关因子2（Nrf2）是一种氧化还原敏感的转录因子，它调节抗氧化酶和几种抗凋亡蛋白的表达，从而赋予细胞抵御氧化应激和凋亡的保护作用。肺癌细胞中Nrf2的组成性激活通过上调谷胱甘肽、硫氧还蛋白以及参与亲电试剂和多种药物解毒的药物外排途径，促进肿瘤发生并导致化疗耐药。在本研究中，我们发现RNA干扰介导的非小细胞肺癌（NSCLC）细胞系（A549和H460）中Nrf2水平的降低导致内源性活性氧（ROS）水平显著升高。同样，γ射线照射诱导的蛋白质羰基形成在Nrf2缺失的肺癌细胞中明显更高，这表明在缺乏Nrf2的情况下电离辐射的致死性增加。通过克隆形成试验测定，Nrf2 shRNA细胞中辐射诱导的蛋白质氧化与存活率降低相关。用抗氧化剂如N - 乙酰 - L - 半胱氨酸、谷胱甘肽和维生素E预处理可消除辐射诱导的细胞死亡，这突出了抗氧化剂在抵御辐射损伤方面的重要性。利用Nrf2基因修饰的功能获得和缺失模型，在小鼠胚胎成纤维细胞中，我们证实Nrf2的组成性激活可抵御电离辐射毒性并赋予放射抗性。因此，针对放射抗性肿瘤中的Nrf2活性可能是克服放射抗性的一种有前景的策略。《抗氧化剂与氧化还原信号》13卷，1627 - 1637页。
Nuclear factor erythroid-2 related factor 2 (Nrf2), a redox-sensitive transcription factor, regulates the expression of antioxidant enzymes and several anti-apoptotic proteins, which confer cytoprotection against oxidative stress and apoptosis. Constitutive activation of Nrf2 in lung cancer cells promotes tumorigenicity and contributes to chemoresistance by upregulation of glutathione, thioredoxin, and the drug efflux pathways involved in detoxification of electrophiles and broad spectrum of drugs. In this study, we show that RNAi-mediated lowering of Nrf2 levels in non-small-cell lung cancer (NSCLC) cell lines (A549 and H460) led to a dramatic increase in endogenous reactive oxygen species (ROS) levels. Similarly, gamma-irradiation-induced formation of protein carbonyls were significantly higher in Nrf2-depleted lung cancer cells, suggesting increased lethality of ionizing radiation in the absence of Nrf2. Radiation-induced protein oxidation in Nrf2shRNA cells correlated with reduced survival as measured by clonogenic assay. Radiation-induced cell death was abrogated by pretreatment with antioxidants such as N-acetyl-L-cysteine, glutathione, and vitamin-E, highlighting the importance of antioxidants in conferring protection against radiation injury. Using genetically-modified gain and loss of function models of Nrf2, in mouse embryonic fibroblasts, we establish that constitutive activation of Nrf2 protects against ionizing radiation toxicity and confers radioresistance. Thus, targeting Nrf2 activity in radioresistant tumors could be a promising strategy to circumvent radioresistance. Antioxid. Redox Signal. 13, 1627-1637.