Fish oil increases mitochondrial phospholipid unsaturation, upregulating reactive oxygen species and apoptosis in rat colonocytes

• Published in: Carcinogenesis (New York) 2002-11, Vol.23 (11), p.1919-1926
• Main Authors: Hong, Mee Young, Chapkin, Robert S., Barhoumi, Rola, Burghardt, Robert C., Turner, Nancy D., Henderson, Cara E., Sanders, Lisa M., Fan, Yang-Yi, Davidson, Laurie A., Murphy, Mary E., Spinka, Christine M., Carroll, Raymond J., Lupton, Joanne R.
• Format: Article
• Language: English
• Subjects: 5-(and -6)-chloromethyl-2; 7’-dichlorodihydrofluorescein diacetate; Animals; Apoptosis - drug effects; Biological and medical sciences; Butyrates - pharmacology; Carcinogenesis, carcinogens and anticarcinogens; Cardiolipins - chemistry; Cardiolipins - metabolism; Caspase 3; Caspases - metabolism; CMH2-DCFDA; Colon - cytology; Colon - metabolism; Corn Oil - pharmacology; Cytochrome c Group - metabolism; DHA; Dietary Fats, Unsaturated - pharmacology; docosahexaenoic acid; eicosapentaenoic acid; Enzyme Activation; EPA; Esters - pharmacology; FAEE; fatty acid ethyl ester diet; Fatty Acids - pharmacology; Fish Oils - pharmacology; Foods and miscellaneous; Hank’s balanced salt solution; HBSS; Intestinal Mucosa - cytology; Intestinal Mucosa - metabolism; Intracellular Membranes - drug effects; Intracellular Membranes - metabolism; Life Sciences (General); Lipid Peroxidation; Male; Medical sciences; Membrane Lipids - chemistry; Membrane Lipids - metabolism; Mitochondria - drug effects; Mitochondria - metabolism; mitochondrial membrane potential; MMP; Oxidative Stress; phosphatidylethanolamine; Phospholipids - chemistry; Phospholipids - metabolism; Rats; Rats, Sprague-Dawley; reactive oxygen species; Reactive Oxygen Species - metabolism; ROS; Tumors
• ISSN: 0143-3334; 1460-2180; 1460-2180
• DOI: 10.1093/carcin/23.11.1919

We have shown that a combination of fish oil (high in n-3 fatty acids) with the butyrate-producing fiber pectin, upregulates apoptosis in colon cells exposed to the carcinogen azoxymethane, protecting against colon tumor development. We now hypothesize that n-3 fatty acids prime the colonocytes such that butyrate can initiate apoptosis. To test this, 30 Sprague–Dawley rats were provided with diets differing in the fatty acid composition (corn oil, fish oil or a purified fatty acid ethyl ester diet). Intact colon crypts were exposed ex vivo to butyrate, and analyzed for reactive oxygen species (ROS), mitochondrial membrane potential (MMP), translocation of cytochrome C to the cytosol, and caspase-3 activity (early events in apoptosis). The fatty acid composition of the three major mitochondrial phospholipids was also determined, and an unsaturation index calculated. The unsaturation index in cardiolipin was correlated with ROS levels (R = 0.99; P = 0.02). When colon crypts from fish oil and FAEE-fed rats were exposed to butyrate, MMP decreased (P = 0.041); and translocation of cytochrome C to the cytosol (P = 0.037) and caspase-3 activation increased (P = 0.032). The data suggest that fish oil may prime the colonocytes for butyrate-induced apoptosis by enhancing the unsaturation of mitochondrial phospholipids, especially cardiolipin, resulting in an increase in ROS and initiating apoptotic cascade.