1 Department of Molecular Biomedicine, Center for Research and Advanced Studies, Mexico City, Mexico.
2 Oncogenomics and Genomics of Bone Diseases Laboratory, National Institute of Genomic Medicine, Clinic Research, Mexico City, Mexico.
Hum Exp Toxicol. 2019 Aug;38(8):951-961. doi: 10.1177/0960327119845035. Epub 2019 Apr 24.
The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) is a master regulator of a battery of antioxidant and detoxificant genes with cytoprotective function. Since Nrf2 inactivation is necessary for the complete execution of apoptosis in the presence of extensive cellular damage caused by oxidative stress, constant activation of Nrf2 may protect tumoral cells from apoptosis. The tumor suppressor gene p53 has been suggested to participate in apoptosis-related repression of Nrf2. Thus, we studied the inactivation of Nrf2 during oxidant-induced apoptosis in a p53 dysfunctional cellular model. Using curcumin dose-response assay and time-response assay in an immortalized lymphoblastoid cell line (control line 45), we observed a time-dependent increase in apoptotic markers such as deoxyribonucleic acid (DNA) fragmentation, phosphatidylserine exposure, and caspase-3, caspase-9 and poly (ADP-ribose) polymerases (PARP) cleavage. Interestingly, at early times of exposure to a proapoptotic dose of curcumin (15 μM), we observed nuclear accumulation of Nrf2 and the expression of Nrf2 target genes, whereas at late exposure times we found a reduction of total and nuclear protein levels of Nrf2 as well as downregulation of Nrf2 target genes in the absence of p53 activation. These data suggest that apoptosis-related inactivation of Nrf2 could occur in a p53 dysfunctional background, opening the possible occurrence of p53-independent mechanism to explain Nrf2 inactivation during apoptosis.
转录因子 Nrf2（红细胞生成素 2 相关因子 2）是一组抗氧化和解毒基因的主要调节剂，具有细胞保护功能。由于 Nrf2 的失活对于在由氧化应激引起的广泛细胞损伤存在的情况下完成细胞凋亡是必需的，因此 Nrf2 的持续激活可能会使肿瘤细胞免受细胞凋亡。肿瘤抑制基因 p53 被认为参与了与细胞凋亡相关的 Nrf2 抑制。因此，我们研究了在 p53 功能失调的细胞模型中，氧化应激诱导的细胞凋亡过程中 Nrf2 的失活。使用姜黄素剂量反应测定和时间反应测定，在一个永生化的淋巴母细胞系（对照系 45）中，我们观察到凋亡标志物如脱氧核糖核酸（DNA）片段化、磷脂酰丝氨酸暴露以及 caspase-3、caspase-9 和多聚（ADP-核糖）聚合酶（PARP）切割的时间依赖性增加。有趣的是，在早期暴露于促凋亡剂量的姜黄素（15 μM）时，我们观察到 Nrf2 的核积累和 Nrf2 靶基因的表达，而在晚期暴露时，我们发现 Nrf2 的总蛋白和核蛋白水平降低，以及 Nrf2 靶基因的下调，而没有 p53 的激活。这些数据表明，在 p53 功能失调的背景下，与细胞凋亡相关的 Nrf2 失活可能发生，这为解释凋亡过程中 Nrf2 失活的 p53 非依赖性机制提供了可能。
