title: Apoptotic and necrotic mechanisms of stress-induced human lens epithelial cell death.
abstract: Exposure to ultraviolet radiation (UVR) and reactive oxygen species (ROS) can damage the human lens and contribute to cataract formation. Recent evidence suggests that apoptosis in lens epithelial cells (LEC) is an initiating event in noncongenital cataract formation in humans and animals. The present study examines the cellular and molecular mechanisms by which environmental (ultraviolet B [UVB]) and chemical (hydrogen peroxide [H(2)O(2)], t-butyl hydroperoxide [TBHP]) stress induces cell death in an SV-40 immortalized human lens epithelial (HLE) cell line. Treatment of HLE cells with UVB, H(2)O(2), and TBHP significantly decreased cell density with LD50 values of 350 J/m(2), 500 muM, and 200 muM, respectively. Cellular morphology, DNA fragmentation, and annexin/propidium iodide staining consistent with apoptosis was observed only in UVB-treated cells, whereas lactate dehydrogenase (LDH) release was significantly higher in H(2)0(2)- and TBHP-treated cells. In addition, activation of apoptotic stress-signaling proteins, including c-Jun NH2-terminal kinase (JNK), caspase-3, and DNA fragmentation factor 45 (DFF45) was observed only in UVB-treated cells. Inhibition of JNK activity increased UVB-induced cell death, suggesting that this pathway may serve a prosurvival role in HLE cells. These findings suggest UVB predominantly induces apoptosis in HLE cells, whereas H(2)O(2) and TBHP induce necrosis.
authors.affiliation: OSU Interdisciplinary PhD Program in Nutrition, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Amy C
authors.initials: AC
authors.lastname: Long
authors.forename: Carmen M H
authors.initials: CM
authors.lastname: Colitz
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bomser
mesh_terms: D017302:Annexins / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D020169:Caspases / Q000528:radiation effects; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects* / Q000528:radiation effects*; D002461:Cell Line, Transformed; D004848:Epithelium / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000528:radiation effects; D007770:L-Lactate Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D007908:Lens, Crystalline / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects*; D007928:Lethal Dose 50; D009336:Necrosis; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014466:Ultraviolet Rays; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D017302:Annexins; D016877:Oxidants; D017382:Reactive Oxygen Species; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases