title: Sodium formate induces autophagy and apoptosis via the JNK signaling pathway of photoreceptor cells.
abstract: Incidents associated with methanol intoxication resulting from the consumption of fake wine occur not infrequently worldwide. Certain individuals are made blind due to methanol poisoning. The present study aimed to investigate the effects of sodium formate exposure on photoreceptor cells (661W cells). The 661W cells were exposed to sodium formate for 6‑24 h and cell viability was determined using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyl‑2H‑tetrazolium bromide (MTT) assay. Subsequently, the 661W cells were exposed to 15 or 30 mM sodium formate for 24 h. The level of apoptosis was determined using Hoechst 33342/propidium iodide staining, visualizing the cells under a fluorescence microscope, and annexin V‑fluorescein isothiocyanate staining, using flow cytometric analysis. Intracellular reactive oxygen species (ROS) were measured using 2',7'‑dichlorofluorescein diacetate (DCFH‑DA) staining, followed by flow cytometric analysis. Autophagy of the 661W cells was measured by monodansylcadaverine staining. The activation of phosphorylated c‑Jun N‑terminal kinase (p‑JNK), B‑cell lymphoma (Bcl‑2), Bcl‑2‑associated X protein, cleaved caspase‑3, cleaved caspase‑9 and microtubule‑associated protein 1A/1B‑light chain 3 (LC3) was assessed by western blotting. The effects of Z‑VAD‑fmk (a pan‑caspase inhibitor) and SP600125 (a JNK inhibitor) on the viability of the sodium formate‑induced 661W cells were determined using an MTT assay. Sodium formate treatment induced a decrease in the viability of the 661W cells in a time‑ and a dose‑dependent manner. In addition, sodium formate at concentrations of 15 or 30 mM markedly increased the level of apoptosis and the ROS levels, as measured by DCFH‑DA staining of the 661W cells. Additionally, 661W cells exposed to sodium formate for 24 h exhibited increased levels of p‑JNK, Bax, cleaved caspase‑3, cleaved caspase‑9 and LC3II (the phosphatidylethanolamine‑modified form of LC3), although the level of Bcl‑2 was decreased. Furthermore, cell cytotoxicity and autophagy were induced upon treatment with sodium formate. Z‑VAD‑fmk and SP600125 were able to effectively circumvent the effects of sodium formate on cell viability. These results suggested that the cytotoxicity induced by sodium formate induces the activation of the JNK signaling pathway, leading to caspase‑dependent apoptosis. Increased levels of autophagy were also observed during the process of 661W cell damage induced by sodium formate.
authors.affiliation: Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China.
authors.forename: Shao-Lin
authors.initials: SL
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China.
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Yang
authors.affiliation: Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China.
authors.forename: Ping
authors.initials: P
authors.lastname: Hu
authors.affiliation: Department of Biology, National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun, Jilin 130024, P.R. China.
authors.forename: Yu-Xin
authors.initials: YX
authors.lastname: Li
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005561:Formates / Q000494:pharmacology*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010786:Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013194:Staining and Labeling; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000873:Anthracenes; D005561:Formates; D008869:Microtubule-Associated Proteins; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C030544:formic acid; C432165:pyrazolanthrone; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases