title: Ebselen induces apoptosis in HepG(2) cells through rapid depletion of intracellular thiols.
abstract: Ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)-one, is a synthetic seleno-organic compound with antioxidant capability. In the present study, we systematically examined the ability of ebselen to induce apoptosis in a human hepatoma cell line, HepG(2). Ebselen-induced apoptosis was evaluated by (i) TdT-mediated dUTP nick end labeling assay; (ii) analysis of sub-G1 cells; (iii) cell morphology, including cell size and granularity examination; and (iv) DNA gel electrophoresis. The results showed that ebselen was able to induce typical apoptosis in HepG(2) cells in a dose- and time-dependent manner. In order to explore the possible mechanisms involved in ebselen-induced apoptosis, the effect of ebselen on intracellular thiol concentrations including reduced glutathione (GSH) and protein thiols and the effect of N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) pretreatment on ebselen-induced apoptosis were investigated. It was found that (i) ebselen rapidly depleted intracellular GSH and protein thiols, moreover, the depletion preceded the occurrence of apoptosis; (ii) NAC, a precursor of intracellular GSH synthesis, significantly alleviated ebselen-induced apoptosis; and (iii) BSO, a specific inhibitor of intracellular GSH synthesis, augmented ebselen-induced apoptosis significantly. Taken together, the present study demonstrates that ebselen is able to induce apoptosis in HepG(2) cells, most probably through rapid depletion of intracellular thiols.
authors.affiliation: Department of Community, Occupational, and Family Medicine, Faculty of Medicine, MD3, National University of Singapore, 16 Medical Drive, 117597, Singapore.
authors.forename: C F
authors.initials: CF
authors.lastname: Yang
authors.forename: H M
authors.initials: HM
authors.lastname: Shen
authors.forename: C N
authors.initials: CN
authors.lastname: Ong
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001393:Azoles / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular; D002470:Cell Survival / Q000187:drug effects*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D020287:In Situ Nick-End Labeling; D054833:Isoindoles; D007700:Kinetics; D008113:Liver Neoplasms; D009363:Neoplasm Proteins / Q000378:metabolism; D016566:Organoselenium Compounds / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000975:Antioxidants; D001393:Azoles; D054833:Isoindoles; D009363:Neoplasm Proteins; D016566:Organoselenium Compounds; D013438:Sulfhydryl Compounds; C042986:ebselen; D005978:Glutathione