Continuous presence of H₂O₂ induces mitochondrial-mediated, MAPK- and caspase-independent growth inhibition and cytotoxicity in human gingival fibroblasts.
The continuous generation of reactive oxygen species (ROS) is one of the most important events that occur during periodontal inflammation. Hydrogen peroxide (H(2)O(2)) is widely used in dental clinics. Many investigators have tried to elucidate the exact effect of H(2)O(2) on human gingival fibroblasts (HGFs). These studies have shown that H(2)O(2) induces growth inhibition and apoptosis in cells. However, the mechanisms involved in H(2)O(2)-induced cell death in HGFs are not completely understood. In this study, we examine how continuously generated H(2)O(2) affects the viability and proliferation of HGFs using glucose oxidase (GO). We also explored the mechanisms by which the continuous presence of H(2)O(2) induces cell death. GO treatment not only inhibited HGF growth and proliferation, but it also induced cell death in HGFs without typical apoptotic features such as nuclear DNA laddering. This GO-mediated cytotoxicity was proportional to the levels of intracellular ROS that were generated, rather than proportional to changes of cellular antioxidant activities. GO treatment also resulted in the loss of mitochondrial membrane potential and the relocation of mitochondrial apoptogenic factors. There was also an acute and severe depletion of cellular ATP levels. However, none of the pharmacological inhibitors specific for mitogen-activated protein kinases (MAPKs) or pancaspase prevented GO-induced cell death. Treatment with either catalase or acteoside significantly attenuated the GO-mediated cytotoxicity in the HGFs, thereby suggesting a protective effect of antioxidants against ROS-mediated gingival damage. Here we demonstrate that continuously generated H(2)O(2) not only inhibits the viability and proliferation of HGFs, but also causes pyknotic/necrotic cell death through mitochondrial stress-mediated, MAPK- and caspase-independent pathways.
Institute of Oral Biosciences (BK21 Program) and School of Dentistry, Chonbuk National University, Jeonju 561-756, South Korea.
Ji-Yeon
JY
Yu
Seung-Youp
SY
Lee
Young-Ok
YO
Son
Xianglin
X
Shi
Soon-Sun
SS
Park
Jeong-Chae
JC
Lee
D000328:Adult; D061945:Caspase Inhibitors; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005881:Gingiva / Q000166:cytology; D005949:Glucose Oxidase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D016877:Oxidants / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D055815:Young Adult
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D020928:Mitogen-Activated Protein Kinases