Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.
Department of Biochemistry and Molecular Biology, Simon Cancer Center Indiana, University School of Medicine, Indianapolis, IN, 46202, USA.
Redox Biol. 2020 Feb;30:101440. doi: 10.1016/j.redox.2020.101440. Epub 2020 Jan 23.
Alterations in the NRF2/KEAP1 pathway result in the constitutive activation of NRF2, leading to the aberrant induction of antioxidant and detoxification enzymes, including NQO1. The NQO1 bioactivatable agent β-lapachone can target cells with high NQO1 expression but relies in the generation of reactive oxygen species (ROS), which are actively scavenged in cells with NRF2/KEAP1 mutations. However, whether NRF2/KEAP1 mutations influence the response to β-lapachone treatment remains unknown. To address this question, we assessed the cytotoxicity of β-lapachone in a panel of NSCLC cell lines bearing either wild-type or mutant KEAP1. We found that, despite overexpression of NQO1, KEAP1 mutant cells were resistant to β-lapachone due to enhanced detoxification of ROS, which prevented DNA damage and cell death. To evaluate whether specific inhibition of the NRF2-regulated antioxidant enzymes could abrogate resistance to β-lapachone, we systematically inhibited the four major antioxidant cellular systems using genetic and/or pharmacologic approaches. We demonstrated that inhibition of the thioredoxin-dependent system or copper-zinc superoxide dismutase (SOD1) could abrogate NRF2-mediated resistance to β-lapachone, while depletion of catalase or glutathione was ineffective. Interestingly, inhibition of SOD1 selectively sensitized KEAP1 mutant cells to β-lapachone exposure. Our results suggest that NRF2/KEAP1 mutational status might serve as a predictive biomarker for response to NQO1-bioactivatable quinones in patients. Further, our results suggest SOD1 inhibition may have potential utility in combination with other ROS inducers in patients with KEAP1/NRF2 mutations.
NRF2/KEAP1 通路的改变导致 NRF2 的组成性激活，导致抗氧化和解毒酶（包括 NQO1）的异常诱导。NQO1 生物激活剂 β-拉帕醌可以靶向 NQO1 表达高的细胞，但依赖于活性氧（ROS）的产生，而具有 NRF2/KEAP1 突变的细胞会积极清除 ROS。然而，NRF2/KEAP1 突变是否会影响对β-拉帕醌治疗的反应尚不清楚。为了解决这个问题，我们评估了β-拉帕醌在一组具有野生型或突变型 KEAP1 的 NSCLC 细胞系中的细胞毒性。我们发现，尽管 NQO1 过表达，KEAP1 突变细胞对β-拉帕醌具有抗性，因为 ROS 的解毒增强，从而防止了 DNA 损伤和细胞死亡。为了评估是否可以通过抑制 NRF2 调节的抗氧化酶来消除对β-拉帕醌的抗性，我们系统地使用遗传和/或药理学方法抑制了四个主要的抗氧化细胞系统。我们证明，抑制硫氧还蛋白依赖性系统或铜锌超氧化物歧化酶（SOD1）可以消除 NRF2 介导的对β-拉帕醌的抗性，而耗尽过氧化氢酶或谷胱甘肽则无效。有趣的是，SOD1 的抑制选择性地使 KEAP1 突变细胞对β-拉帕醌敏感。我们的结果表明，NRF2/KEAP1 突变状态可能作为患者对 NQO1 生物激活醌反应的预测生物标志物。此外，我们的结果表明，SOD1 抑制可能在与 KEAP1/NRF2 突变患者的其他 ROS 诱导剂联合使用时具有潜在的应用价值。
