Monitoring NAD(P)H by an ultrasensitive fluorescent probe to reveal reductive stress induced by natural antioxidants in HepG2 cells under hypoxia
Monitoring NAD(P)H by an ultrasensitive fluorescent probe to reveal reductive stress induced by natural antioxidants in HepG2 cells under hypoxia
复制标题
通过超灵敏荧光探针监测 NAD(P)H，揭示缺氧下 HepG2 细胞中天然抗氧化剂诱导的还原应激
DOI：
10.1039/c9sc02020a
复制
发表时间：
2019-09-21
期刊：
影响因子：
8.4
通讯作者：
Tang, Bo
中科院分区：
文献类型：
--
作者：
Pan, Xiaohong;Zhao, Yuehui;Tang, Bo
还原性应激与氧化应激相反，是氧化还原平衡状态的一种紊乱，对生物系统有害。几十年来，氧化应激在肿瘤治疗中的作用一直是人们关注的焦点，而还原性应激的作用却很少被研究。在此，我们报道了三种天然抗氧化剂（白藜芦醇、姜黄素和celastrol）诱导的还原性应激的抗癌作用。考虑到实体肿瘤微环境处于缺氧状态，我们进行了缺氧条件下的细胞实验。为了观察还原性胁迫，我们首先研制了一种特异成像还原性胁迫标志物NAD(P)H的超灵敏荧光探针（TCF-MQ）。TCF-MQ对NAD(P)H反应迅速，灵敏度高，检出限为6 nM。在TCF-MQ的帮助下，我们发现在缺氧条件下，用药理学剂量的三种天然抗氧化剂处理HepG2细胞，在细胞死亡前产生高水平的NAD(P)H。过量的NAD(P)H导致的不是氧化应激，而是还原性应激。相比之下，在常压条件下，三种天然抗氧化剂诱导的细胞死亡过程中不存在还原性应激。因此，我们假设天然抗氧化剂在缺氧条件下诱导癌细胞死亡的机制可能与还原性应激有关。
Reductive stress, the opposite of oxidative stress, represents a disorder in the redox balance state which is harmful to biological systems. For decades, the role of oxidative stress in tumor therapy has been the focus of attention, while the effects of reductive stress have been rarely studied. Here, we report the anti-cancer effects of reductive stress induced by three natural antioxidants (resveratrol, curcumin and celastrol). Considering the fact that the solid tumor microenvironment suffers from hypoxia, we performed cell experiments under hypoxic conditions. In order to observe the reductive stress, we first developed an ultrasensitive fluorescent probe (TCF-MQ) for specifically imaging NAD(P)H which is a marker of reductive stress. TCF-MQ responded to NAD(P)H rapidly and exhibited high sensitivity with a detection limit of 6 nM. With the help of TCF-MQ, we found that upon the treatment of HepG2 cells with pharmacological doses of three natural antioxidants under hypoxic conditions, high levels of NAD(P)H were produced before cell death. The excess NAD(P)H resulted in reductive stress instead of oxidative stress. In contrast, under normoxic conditions, there was no reductive stress involved in the process of cell death induced by three natural antioxidants. Therefore, we hypothesize that the mechanism of cancer cell death induced by natural antioxidants under hypoxia should be attributed to the reductive stress.