Journal Article

The role of docosahexaenoic acid in mediating mitochondrial membrane lipid oxidation and apoptosis in colonocytes

Yeevoon Ng, Rola Barhoumi, Ronald B. Tjalkens, Yang-Yi Fan, Satya Kolar, Naisyin Wang, Joanne R. Lupton and Robert S. Chapkin

in Carcinogenesis

Volume 26, issue 11, pages 1914-1921
Published in print November 2005 | ISSN: 0143-3334
Published online June 2005 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgi163
The role of docosahexaenoic acid in mediating mitochondrial membrane lipid oxidation and apoptosis in colonocytes

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Docosahexaenoic acid (DHA, 22:6 n-3) from fish oil, and butyrate, a fiber fermentation product, work coordinately to protect against colon tumorigenesis in part by inducing apoptosis. We have recently demonstrated that dietary DHA is incorporated into mitochondrial membrane phospholipids, thereby enhancing oxidative stress induced by butyrate metabolism. In order to elucidate the subcellular origin of oxidation induced by DHA and butyrate, immortalized young adult mouse colonocytes were treated with 0–200 μM DHA or linoleic acid (LA, 18:2 n-6; control) for 72 h with or without 5 mM butyrate for the final 24 h. Cytosolic reactive oxygen species, membrane lipid oxidation, and mitochondrial membrane potential (MP), were measured by live-cell fluorescence microscopy. After 24 h of butyrate treatment, DHA primed cells exhibited a 151% increase in lipid oxidation (P < 0.01), compared with no butyrate treatment, which could be blocked by a mitochondria-specific antioxidant, 10-(6′-ubiquinoyl) decyltriphenylphosphonium bromide (MitoQ) (P < 0.05). Butyrate treatment of LA pretreated cells did not show any significant effect. In the absence of butyrate, DHA treatment, compared with LA, increased resting MP by 120% (P < 0.01). In addition, butyrate-induced mitochondrial membrane potential (MP), dissipation was 21% greater in DHA primed cells as compared with LA at 6 h. This effect was reversed by preincubation with inhibitors of the mitochondrial permeability transition pore, cyclosporin A or bongkrekic acid (1 μM). The functional importance of these events is supported by the demonstration that DHA and butyrate-induced apoptosis is blocked by MitoQ. These data indicate that DHA and butyrate potentiate mitochondrial lipid oxidation and the dissipation of MP which contribute to the induction of apoptosis.

Keywords: α-TOC, alpha-tocopherol; BKA, bongkrekic acid; CSA, cyclosporine A; CumOOH, cumene hydroperoxide; DHA, docosahexaenoic acid; DPPP, diphenyl-1-pyrenylphosphine; EPA, eicosapentaenoic acid; ELISA, enzyme-linked immunosorbent assay; LA, linoleic acid; LDH, lactate dehydrogenase; MitoQ, 10-(6′-ubiquinoyl) decyltriphenylphosphonium bromide; MP, mitochondrial membrane potential; MPT, mitochondrial permeability transition; PUFA, polyunsaturated fatty acids; ROS, reactive oxygen species; YAMC, young adult mouse colonocyte

Journal Article.  6169 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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