Effects of cholesterol oxides on cell death induction and calcium increase in human neuronal cells (SK-N-BE) and evaluation of the protective effects of docosahexaenoic acid (DHA; C22:6 n-3)

• Published in: Steroids 2015-07, Vol.99 (Pt B), p.238-247
• Main Authors: Zarrouk, Amira, Nury, Thomas, Samadi, Mohammad, O’Callaghan, Yvonne, Hammami, Mohamed, O’Brien, Nora M., Lizard, Gérard, Mackrill, John J.
• Format: Article
• Language: English
• Subjects: Antioxidants - pharmacology; Apoptosis - drug effects; Autophagy - drug effects; Biomarkers - metabolism; Calcium; Calcium - metabolism; Cell death; Cell Line; Cell Proliferation - drug effects; Cholesterol - pharmacology; Condensed Matter; Docosahexaenoic Acids - pharmacology; Humans; Materials Science; Mitochondria - drug effects; Mitochondria - metabolism; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Neuroprotective Agents - pharmacology; Oxidative stress; Oxides - pharmacology; Oxysterols; Physics; SK-N-BE; Superoxide Dismutase - metabolism; Superoxides - metabolism
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2015.01.018

•Cholesterol oxidized at C7, C24 and C27 induced an oxidative stress on SK-N-BE cells.•Cell death induction was observed with cholesterol oxidized at C7 and C24.•Cell death induction was associated with a slight Ca2+ increase.•Cholesterol oxidized at C4 and C6 were cytostatic.•DHA slightly counteracted oxysterol-induced side effects. Some oxysterols are associated with neurodegenerative diseases. Their lipotoxicity is characterized by an oxidative stress and induction of apoptosis. To evaluate the capacity of these molecules to trigger cellular modifications involved in neurodegeneration, human neuronal cells SK-N-BE were treated with 7-ketocholesterol, 7α- and 7β-hydroxycholesterol, 6α- and 6β-hydroxycholesterol, 4α- and 4β-hydroxycholesterol, 24(S)-hydroxycholesterol and 27-hydroxycholesterol (50–100μM, 24h) without or with docosahexaenoic acid (50μM). The effects of these compounds on mitochondrial activity, cell growth, production of reactive oxygen species (ROS) and superoxide anions (O2−), catalase and superoxide dismutase activities were determined. The ability of the oxysterols to induce increases in Ca2+ was measured after 10min and 24h of treatment using fura-2 videomicroscopy and Von Kossa staining, respectively. Cholesterol, 7-ketocholesterol, 7β-hydroxycholesterol, and 24(S)-hydroxycholesterol (100μM) induced mitochondrial dysfunction, cell growth inhibition, ROS overproduction and cell death. A slight increase in the percentage of cells with condensed and/or fragmented nuclei, characteristic of apoptotic cells, was detected. With 27-hydroxycholesterol, a marked increase of O2− was observed. Increases in intracellular Ca2+ were only found with 7-ketocholesterol, 7β-hydroxycholesterol, 24(S)-hydroxycholesterol and 27-hydroxycholesterol. Pre-treatment with docosahexaenoic acid showed some protective effects depending on the oxysterol considered. According to the present data, 7-ketocholesterol, 7β-hydroxycholesterol, 24(S)-hydroxycholesterol and 27-hydroxycholesterol could favor neurodegeneration by their abilities to induce mitochondrial dysfunctions, oxidative stress and/or cell death associated or not with increases in cytosolic calcium levels.