Protection of retinal pigment epithelial cells from oxidative damage by oltipraz, a cancer chemopreventive agent.
OBJECTIVE
To determine whether oltipraz (4-methyl-5-pyrazinyl-3H-1,2-dithiole-3-thione) protects against oxidative injury in cultured human retinal pigment epithelial (hRPE) cells.


METHODS
Primary cultured hRPE cells were incubated with various concentrations of oltipraz followed by treatment with the chemical oxidant tert-butylhydroperoxide (tBH). Cell viability was assessed by release of lactate dehydrogenase (LDH) and cleavage of WST-1. Intracellular and mitochondrial levels of glutathione (GSH) were measured by HPLC. Glutathione S-transferase (GST), NADPH-quinone reductase (NQR), and glutathione peroxidase (GPx) were measured by specific enzyme activity assays.


RESULTS
Treatment of hRPE cells with oltipraz inhibited tBH-induced cell death in a concentration-dependent manner with significant inhibition at 50 micro M. Olitpraz (50 micro M) increased GSH levels in hRPE cells by approximately 18% and in hRPE mitochondrial fractions by approximately 50% after 24 hours of exposure. Treatment with oltipraz increased GST and NQR activities by approximately 21% and 11%, respectively.


CONCLUSIONS
Oltipraz protects hRPE cells against tBH induced injury. The mechanism of protection is likely to include increased cellular and mitochondrial GSH levels and induction of detoxification enzymes, including GST and NQR. Dietary supplementation with oltipraz or other dithiolethiones may help protect the hRPE against oxidant induced injury.
Nelson
Kasey C
KC
Departments of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA.
Armstrong
Jeffrey S
JS
Moriarty
Siobhan
S
Cai
Jiyang
J
Wu
Mei-Whey H
MW
Sternberg
Paul
P
Jones
Dean P
DP
D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D019610:Cytoprotection / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D018384:Oxidative Stress; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D013871:Thiones; D013876:Thiophenes; D020122:tert-Butylhydroperoxide / Q000633:toxicity
D016588:Anticarcinogenic Agents; D011719:Pyrazines; D017382:Reactive Oxygen Species; D013871:Thiones; D013876:Thiophenes; C026209:oltipraz; D020122:tert-Butylhydroperoxide; D007770:L-Lactate Dehydrogenase; D005979:Glutathione Peroxidase; D016660:NAD(P)H Dehydrogenase (Quinone); D005982:Glutathione Transferase; D005978:Glutathione