Chemical hypoxia-induced cell death in human glioma cells: role of reactive oxygen species, ATP depletion, mitochondrial damage and Ca2+.
This study was undertaken to evaluate whether chemical hypoxia-induced cell injury is a result of reactive oxygen species (ROS) generation, ATP depletion, mitochondrial permeability transition, and an increase in intracellular Ca2+, in A172 cells, a human glioma cell line. Chemical hypoxia was induced by incubating cells with antimycin A, an inhibitor of mitochondrial electron transport, in a glucose-free medium. Exposure of cells to chemical hypoxia resulted in cell death, ROS generation, ATP depletion, and mitochondrial permeability transition. The H2O2 scavenger pyruvate prevented cell death, ROS generation, and mitochondrial permeability transition induced by chemical hypoxia. In contrast, changes mediated by chemical hypoxia were not affected by hydroxyl radical scavengers. Antioxidants did not affect cell death and ATP depletion induced by chemical hypoxia, although they prevented ROS production and mitochondrial permeability transition induced by chemical hypoxia. Chemical hypoxia did not increase lipid peroxidation even when antimycin A was increased to 50 microM, whereas the oxidant t-butylhydroperoxide caused a significant increase in lipid peroxidation, at a concentration that is less effective than chemical hypoxia in inducing cell death. Fructose protected against cell death and mitochondrial permeability transition induced by chemical hypoxia. However, ROS generation and ATP depletion were not prevented by fructose. Chemical hypoxia caused the early increase in intracellular Ca2+. The cell death and ROS generation induced by chemical hypoxia were altered by modulation of intracellular Ca2+ concentration with ruthenium red, TMB-8, and BAPTA/AM. However, mitochondrial permeability transition was not affected by these compounds. These results indicate that chemical hypoxia causes cell death, which may be, in part, mediated by H2O2 generation via a lipid peroxidation-independent mechanism and elevated intracellular Ca2+. In addition, these data suggest that chemical hypoxia-induced cell death is not associated directly with ATP depletion and mitochondrial permeability transition.
Jeong
Jae Ick
JI
Department of Neurosurgery, College of Medicine, Pusan National University, Pusan 602-739, Korea.
Lee
Young Woo
YW
Kim
Yong Keun
YK
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000968:Antimycin A / Q000494:pharmacology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D005910:Glioma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D015227:Lipid Peroxidation; D008928:Mitochondria / Q000187:drug effects*; D017382:Reactive Oxygen Species; D014407:Tumor Cells, Cultured
D017382:Reactive Oxygen Species; D000968:Antimycin A; D000255:Adenosine Triphosphate; D002118:Calcium