title: The role of thiol reduction in hydroquinone-induced apoptosis in HEK293 cells.
abstract: Hydroquinone (HQ) is a chemical used as a reducing agent, antioxidant, polymerization inhibitor, and chemical intermediate. It has a minor use as a bleaching agent in dermatologic preparations. HQ also occurs as a main metabolite of benzene. In the present study, HQ-induced apoptosis was evaluated by cell morphology changes, determination of phosphatidylserine (PS) externalization and analysis of sub-G1 cells. The effect of HQ on intracellular thiol concentration, including glutathione and protein thiol, and the effect of N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) pretreatment on HQ-induced apoptosis were investigated. The results showed that HQ was able to induce typical apoptosis in HEK293 cells (human embryonic kidney cells) in a dose-dependent manner. Intracellular thiol, including glutathione and protein thiol, was decreased following treatment with HQ. NAC, a precursor of intracellular GSH synthesis, significantly inhibited HQ-induced apoptosis. However, BSO, a specific inhibitor of intracellular GSH synthesis, enhanced HQ-induced apoptosis significantly. Taken together, the present study demonstrates that HQ is able to induce apoptosis in HEK293 cells, most probably through depletion of intracellular thiol. The results also suggest that, at least in HEK293 cells, the control of intracellular redox homeostasis has a central role in the regulation of cell death induced by HQ.
authors.affiliation: Department of Toxicology, School of Public Health, Peking University, 38 Xueyuan Road, Beijing 100083, People's Republic of China.
authors.forename: Dong-Xiao
authors.initials: DX
authors.lastname: Shen
authors.forename: Xu
authors.initials: X
authors.lastname: Shi
authors.forename: Juan-Ling
authors.initials: JL
authors.lastname: Fu
authors.forename: Ying-Mei
authors.initials: YM
authors.lastname: Zhang
authors.forename: Zong-Can
authors.initials: ZC
authors.lastname: Zhou
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D006873:Hydroquinones; D013438:Sulfhydryl Compounds; D019328:Buthionine Sulfoximine; D005978:Glutathione; D000111:Acetylcysteine; C031927:hydroquinone