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Induction of autophagy and cell death by tamoxifen in cultured retinal pigment epithelial and photoreceptor cells.
MedLine Citation:
PMID:  22786900     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Purpose. To investigate the mechanism of tamoxifen (TAM) retinotoxicity using human retinal pigment epithelial-derived (ARPE-19) and photoreceptor-derived (661W) cells. Methods. Cultured ARPE-19 and 661W cells were treated with 5 to 10 μM TAM, and the resultant cell death was quantified using lactate dehydrogenase (LDH) release assay. Cellular oxidative stress was determined by measuring 5-(and-6)-carboxy-2',7'-dichlorohydrofluorescein diacetate (H2-DCFDA) fluorescence. Changes in intracellular free-zinc levels were monitored using the zinc-specific fluorescent dye, FluoZin-3 AM. Autophagic vacuole formation was morphologically assessed in ARPE-19 and 661W cells transfected with the fluorescent protein-conjugated markers, RFP-LC3 or GFP-LC3. Results. Following exposure to TAM, both ARPE-19 and 661W cells developed cytosolic vacuoles within 1 h and underwent cell death within 18 h. In both cell types, TAM-induced cell death was accompanied by increased oxidative stress and elevated zinc levels, and was attenuated by the antioxidant NAC (N-Acetyl-L-Cysteine) or the zinc chelator TPEN (N,N,N'N'-tetrakis(-)[2-pyridylmethyl]-ethylenediamine). The levels of LC3-II as well as the number of autophagic vacuoles (AVs) increased after TAM treatment. Double staining for lysosomes and AVs showed that autolysosome formation proceeded normally. Consistent with this, autophagy flux was increased. Finally, as shown in other cases of autophagic cell death, lysosomal membrane permeabilization (LMP) as well as caspase-dependent apoptosis contributed to TAM-induced cell death.Conclusions. ARPE-19 and 661W cells were similarly vulnerable to TAM-induced cytotoxicity. Increases in zinc levels and oxidative stress, excessive activation of autophagy flux, and ultimately the occurrence of LMP and consequent caspase activation may contribute to the well-established retinal cytotoxicity of TAM.
Authors:
Kyung Sook Cho; Young Hee Yoon; Jeong A Choi; Sook-Jeong Lee; Jae-Young Koh
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-10
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  -     ISSN:  1552-5783     ISO Abbreviation:  -     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-7-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
NRL Neural Injury Research Center and the Department of Neurology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea (South), Republic of.
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