title: Curcumin protects retinal pigment epithelial cells against oxidative stress via induction of heme oxygenase-1 expression and reduction of reactive oxygen.
abstract: OBJECTIVE
  To determine whether curcumin induces expression of the defensive enzyme heme oxygenase-1 (HO-1) and protects cells against oxidative stress in cultured human retinal pigment epithelial cells.
  
  
  METHODS
  Effective concentrations and toxicities of curcumin were determined after 3 h of curcumin treatment with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Confluent human retinal pigment epithelium cell lines (ARPE-19) were preincubated with curcumin and oxidatively challenged with H(2)O(2). HO-1 expression was determined with western blot analysis. To confirm the protective role of HO-1 in oxidative stress, small interfering RNA (siRNA) against HO-1 or inhibitor of HO-1 was treated with curcumin in retinal pigment epithelium cells. Intracellular levels of reactive oxygen species (ROS) were measured with flow cytometry and confocal microscopy. Apoptosis was evaluated with Annexin V-fluoroscein isothiocyanate staining.
  
  
  RESULTS
  Curcumin had little cytotoxicity at concentrations less than 30 μM, and HO-1 expression was the highest at the 15 μM concentration. At this concentration, curcumin also increased the cytoprotective effect against the oxidative stress of H(2)O(2) through the reduction of ROS levels in human retinal pigment epithelial cells. Curcumin's effect on the reduction of ROS was mediated by the increase in HO-1 expression.
  
  
  CONCLUSIONS
  Curcumin upregulated the oxidative stress defense enzyme HO-1 and may protect human retinal pigment epithelial cells against oxidative stress by reducing ROS levels.
authors.affiliation: Department of Ophthalmology, Ulsan University Hospital, Ulsan, Republic of Korea.
authors.forename: Je Moon
authors.initials: JM
authors.lastname: Woo
authors.forename: Da-Yong
authors.initials: DY
authors.lastname: Shin
authors.forename: Sung Ju
authors.initials: SJ
authors.lastname: Lee
authors.forename: Yeonsoo
authors.initials: Y
authors.lastname: Joe
authors.forename: Min
authors.initials: M
authors.lastname: Zheng
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Yim
authors.forename: Zak
authors.initials: Z
authors.lastname: Callaway
authors.forename: Hun Taeg
authors.initials: HT
authors.lastname: Chung
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D019610:Cytoprotection; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007093:Imidazoles; D011725:Pyridines; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D051547:Heme Oxygenase-1; D003474:Curcumin; C093642:SB 203580