Mitochondrial superoxide anions induced by exogenous oxidative stress determine tumor cell fate: an individual cell-based study

• Published in: Journal of Zhejiang University. B. Science Vol. 20; no. 4; pp. 310 - 321
• Main Authors: Pan, Hui, Wang, Bao-hui, Li, Zhou-bin, Gong, Xing-guo, Qin, Yong, Jiang, Yan, Han, Wei-li
• Format: Journal Article
• Language: English
• Published: Hangzhou Zhejiang University Press 01.04.2019
• Subjects: Biomedical and Life Sciences; Biomedicine; 氧自由基动力学; Superoxide anion; Reactive oxygen species (ROS) dynamics; signaling; 内源性凋亡途径; 超氧阴离子; Individual cell; 钙信号; R73-3; Intrinsic apoptotic pathway; 单个细胞; Ca; Individual cell; Superoxide anion; Reactive oxygen species (ROS) dynamics; Intrinsic apoptotic pathway; Ca2+ signaling
• ISSN: 1673-1581; 1862-1783
• DOI: 10.1631/jzus.B1800319

Objective Reactive oxygen species (ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H 2 O 2 stimuli. Methods Modified microfluidics and imaging techniques were used to determine O 2 •− levels and construct an O 2 •− reaction network. To elucidate the consequences of increased O 2 •− input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca 2+ levels, mitochondrial Ca 2+ uptake, auto-amplification of intra-cellular ROS and the intrinsic apoptotic pathway. Results and conclusions Results from a modified microchip demonstrated that 1 mmol/L H 2 O 2 induced a rapid increase in cellular O 2 •− levels (>27 vs. >406 amol in 20 min), leading to increased cellular oxidizing power (evaluated by ROS levels) and decreased reducing power (evaluated by glutathione (GSH) levels). In addition, we examined the dynamics of cytosolic Ca 2+ and mitochondrial Ca 2+ by confocal laser scanning microscopy and confirmed that Ca 2+ stores in the endoplasmic reticulum were the primary source of H 2 O 2 -induced cytosolic Ca 2+ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca 2+ signals between organelles, ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.