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Seidel U, Eberhardt K, Wiebel M, Luersen K, Ipharraguerre IR, Haegele FA, Winterhalter P, Bosy-Westphal A, Schebb NH, Rimbach G. Stearidonic acid improves eicosapentaenoic acid status: studies in humans and cultured hepatocytes. Front Nutr 2024; 11:1359958. [PMID: 38974810 PMCID: PMC11225816 DOI: 10.3389/fnut.2024.1359958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/15/2024] [Indexed: 07/09/2024] Open
Abstract
Background Ahiflower oil from the seeds of Buglossoides arvensis is rich in α-linolenic acid (ALA) and stearidonic acid (SDA). ALA and SDA are potential precursor fatty acids for the endogenous synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are n3-long chain polyunsaturated fatty acids (n3-LC-PUFAS), in humans. Since taurine, an amino sulfonic acid, is often associated with tissues rich in n3-LC-PUFAS (e.g., in fatty fish, human retina), taurine may play a role in EPA- and DHA-metabolism. Objective To examine the capacity of the plant-derived precursor fatty acids (ALA and SDA) and of the potential fatty acid metabolism modulator taurine to increase n3-LC-PUFAS and their respective oxylipins in human plasma and cultivated hepatocytes (HepG2 cells). Methods In a monocentric, randomized crossover study 29 healthy male volunteers received three sequential interventions, namely ahiflower oil (9 g/day), taurine (1.5 g/day) and ahiflower oil (9 g/day) + taurine (1.5 g/day) for 20 days. In addition, cultivated HepG2 cells were treated with isolated fatty acids ALA, SDA, EPA, DHA as well as taurine alone or together with SDA. Results Oral ahiflower oil intake significantly improved plasma EPA levels (0.2 vs. 0.6% of total fatty acid methyl esters (FAMES)) in humans, whereas DHA levels were unaffected by treatments. EPA-levels in SDA-treated HepG2 cells were 65% higher (5.1 vs. 3.0% of total FAMES) than those in ALA-treated cells. Taurine did not affect fatty acid profiles in human plasma in vivo or in HepG2 cells in vitro. SDA-rich ahiflower oil and isolated SDA led to an increase in EPA-derived oxylipins in humans and in HepG2 cells, respectively. Conclusion The consumption of ahiflower oil improves the circulating levels of EPA and EPA-derived oxylipins in humans. In cultivated hepatocytes, EPA and EPA-derived oxylipins are more effectively increased by SDA than ALA.
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Affiliation(s)
- Ulrike Seidel
- Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany
| | | | - Michelle Wiebel
- Chair of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal, Germany
| | - Kai Luersen
- Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany
| | | | - Franziska A. Haegele
- Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany
| | | | - Anja Bosy-Westphal
- Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany
| | - Nils Helge Schebb
- Chair of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal, Germany
| | - Gerald Rimbach
- Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany
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Kjær MA, Ruyter B, Berge GM, Sun Y, Østbye TKK. Regulation of the Omega-3 Fatty Acid Biosynthetic Pathway in Atlantic Salmon Hepatocytes. PLoS One 2016; 11:e0168230. [PMID: 27973547 PMCID: PMC5156434 DOI: 10.1371/journal.pone.0168230] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022] Open
Abstract
Limited availability of the n-3 fatty acids EPA and DHA have led to an interest in better understanding of the n-3 biosynthetic pathway and its regulation. The biosynthesis of alpha-linolenic acid to EPA and DHA involves several complex reaction steps including desaturation-, elongation- and peroxisomal beta-oxidation enzymes. The aims of the present experiments were to gain more knowledge on how this biosynthesis is regulated over time by different doses and fatty acid combinations. Hepatocytes isolated from salmon were incubated with various levels and combinations of oleic acid, EPA and DHA. Oleic acid led to a higher expression of the Δ6 fatty acid desaturase (fad) genes Δ6fad_a, Δ6fad_b, Δ6fad_c and the elongase genes elovl2 compared with cells cultured in medium enriched with DHA. Further, the study showed rhythmic variations in expression over time. Levels were reached where a further increase in specific fatty acids given to the cells not stimulated the conversion further. The gene expression of Δ6fad_a_and Δ6fad_b responded similar to fatty acid treatment, suggesting a co-regulation of these genes, whereas Δ5fad and Δ6fad_c showed a different regulation pattern. EPA and DHA induced different gene expression patterns, especially of Δ6fad_a. Addition of radiolabelled alpha-linolenic acid to the hepatocytes confirmed a higher degree of elongation and desaturation in cells treated with oleic acid compared to cells treated with DHA. This study suggests a complex regulation of the conversion process of n-3 fatty acids. Several factors, such as that the various gene copies are differently regulated, the gene expression show rhythmic variations and gene expression only affected to a certain level, determines when you get the maximum conversion of the beneficial n-3 fatty acids.
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García-Pelayo MC, García-Peregrín E, Martínez-Cayuela M. Influence of environmental medium on membrane fatty acid composition of Reuber H35 hepatoma cells. FRONTIERS IN LIFE SCIENCE 2014. [DOI: 10.1080/21553769.2013.860406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Bioconversion of α-linolenic acid into n-3 long-chain polyunsaturated fatty acid in hepatocytes and ad hoc cell culture optimisation. PLoS One 2013; 8:e73719. [PMID: 24040040 PMCID: PMC3770698 DOI: 10.1371/journal.pone.0073719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 07/23/2013] [Indexed: 11/23/2022] Open
Abstract
This study aimed to establish optimal conditions for a cell culture system that would allow the measurement of 18∶3n-3 (ALA) bioconversion into n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA), and to determine the overall pathway kinetics. Using rat hepatocytes (FaO) as model cells, it was established that a maximum 20∶5n-3 (EPA) production from 50 µM ALA initial concentration was achieved after 3 days of incubation. Next, it was established that a gradual increase in the ALA concentration from 0 up to 125µM lead to a proportional increase in EPA, without concomitant increase in further elongated or desaturated products, such as 22∶5n-3 (DPA) and 22∶6n-3 (DHA) in 3 day incubations. Of interest, ALA bioconversion products were observed in the culture medium. Therefore, in vitro experiments disregarding the medium fatty acid content are underestimating the metabolism efficiency. The novel application of the fatty acid mass balance (FAMB) method on cell culture system (cells with medium) enabled quantifying the apparent enzymatic activities for the biosynthesis of n-3 LC-PUFA. The activity of the key enzymes was estimated and showed that, under these conditions, 50% (Km) of the theoretical maximal (Vmax = 3654 µmol.g−1 of cell protein.hour−1) Fads2 activity on ALA can be achieved with 81 µM initial ALA. Interestingly, the apparent activity of Elovl2 (20∶5n-3 elongation) was the slowest amongst other biosynthesis steps. Therefore, the possible improvement of Elovl2 activity is suggested toward a more efficient DHA production from ALA. The present study proposed and described an ad hoc optimised cell culture conditions and methodology towards achieving a reliable experimental platform, using FAMB, to assist in studying the efficiency of ALA bioconversion into n-3 LC-PUFA in vitro. The FAMB proved to be a powerful and inexpensive method to generate a detailed description of the kinetics of n-3 LC-PUFA biosynthesis enzymes activities in vitro.
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Sedan D, Giannuzzi L, Rosso L, Marra CA, Andrinolo D. Biomarkers of prolonged exposure to microcystin-LR in mice. Toxicon 2013; 68:9-17. [PMID: 23506857 DOI: 10.1016/j.toxicon.2013.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/27/2013] [Accepted: 03/01/2013] [Indexed: 01/09/2023]
Abstract
The effects of prolonged exposure to microcystins (MCs) on health are not yet sufficiently understood and this type of poisoning is often undiagnosed. Even though chronic exposure has been linked with liver cancer and alterations have been described in liver damage marker enzymes in exposed populations, there are not profile parameters that indicate prolonged exposure to microcystins. The aim of this work is to determine, based on an animal model of prolonged exposure to successive i.p. doses of 25 μg MC-LR/kg body weight, several plasma parameters which could be useful as exposure biomarkers. Hemoglobin (Hb) and methemoglobin (MetHb) levels were determined on blood samples. We also studied plasma levels of hydroperoxides (ROOHs), α-tocopherol, glutathione and lipid profile as well as superoxide dismutase (SOD) and catalase (CAT) erythrocyte activities. In addition, the determination of MC-LR levels in liver, kidney, plasma, urine and feces of treated mice was carried out. We found that alteration in MetHb, ROOHs, glutathione, α-tocopherol levels, SOD activity and plasma lipid profile, correlates with those expected if the alteration derived from hepatic damage. The alterated plasma paramenters together with MC-LR determination could be used as biomarkers, helpful tools in screening and epidemiological studies.
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Affiliation(s)
- Daniela Sedan
- Área de Toxicología, Facultad de Ciencias Exactas, Universidad Nacional de La Plata UNLP, 1900 La Plata, Argentina
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Rebolledo A, Rebolledo OR, Marra CA, García ME, Roldán Palomo AR, Rimorini L, Gagliardino JJ. Early alterations in vascular contractility associated to changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue. Cardiovasc Diabetol 2010; 9:65. [PMID: 20964827 PMCID: PMC2974659 DOI: 10.1186/1475-2840-9-65] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 10/21/2010] [Indexed: 12/31/2022] Open
Abstract
Aim To test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility. Methods Adult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K+-induced depolarization using intact and thereafter PVAT-deprived rings. Results Comparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K+-induced depolarization either in CD or FRD rats. Conclusions FRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.
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Affiliation(s)
- Alejandro Rebolledo
- GINFIV - Grupo de Investigación en Fisiología Vascular, Grupo Vinculado a CENEXA (UNLP - CONICET LA PLATA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
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Maté SM, Layerenza JP, Ves-Losada A. Arachidonic acid pools of rat kidney cell nuclei. Mol Cell Biochem 2010; 345:259-70. [DOI: 10.1007/s11010-010-0580-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 08/28/2010] [Indexed: 11/29/2022]
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Sedan D, Andrinolo D, Telese L, Giannuzzi L, de Alaniz MJ, Marra CA. Alteration and recovery of the antioxidant system induced by sub-chronic exposure to microcystin-LR in mice: Its relation to liver lipid composition. Toxicon 2010; 55:333-42. [DOI: 10.1016/j.toxicon.2009.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 08/12/2009] [Accepted: 08/14/2009] [Indexed: 10/20/2022]
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García ME, Marra CA, Rebolledo OR. Glycoxidative stress-induced damage on lipid profile in a fructose-enriched diet model of insulin resistance in rats. Arch Physiol Biochem 2010; 116:42-9. [PMID: 20082562 DOI: 10.3109/13813450903527713] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To study alterations in plasma lipid profile and oxidative damage to lipoprotein fractions (LF) and their fatty acids during an early insulin-resistant and increased oxidative state developed by a fructose-rich diet (FRD). METHODS AND RESULTS Wistar rats were fed a commercial diet with (FRD) or without (CD) 10% fructose in the drinking water. After 3 weeks, plasma glucose, triglyceride (TG), insulin (I), fructosamine (F), free fatty acids (FFA) and lipid profile (total cholesterol [TC] and HDL-C, LDL-C and VLDL-C sub-fractions) were determined. The insulin sensitivity HOMA index was assessed. FRD-fed rats had higher plasma TG, I, and F levels; increased HOMA; decreased HDL-C and LDL-C; augmented VLDL-C and TC/HDL-C, and TG/HDL-C atherogenic risk scores. LF of FRD rats had increased oxidative damage on the fatty acyl profile and in copper-induced lipoperoxidation. CONCLUSIONS Fructose feeding early increases the atherogenic risk inducing an insulin resistant-glycoxidative state that affects plasma lipid profiles.
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Affiliation(s)
- M E García
- Centro de Endocrinología Experimental y Aplicada, UNLP-CONICET La Plata, PAHO/WHO Collaborating Center, Argentina
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de Catalfo GEH, de Alaniz MJT, Marra CA. Influence of Commercial Dietary Oils on Lipid Composition and Testosterone Production in Interstitial Cells Isolated from Rat Testis. Lipids 2009; 44:345-57. [DOI: 10.1007/s11745-008-3277-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 12/04/2008] [Indexed: 12/31/2022]
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Breguet V, Vojinovic V, Stockar UV, Marison IW. Enzymatic hydrolysis of organic-core microcapsules to produce aqueous-core microcapsules. J Microencapsul 2008; 25:179-86. [DOI: 10.1080/02652040701843461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12
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Hurtado de Catalfo GE, de Alaniz MJ, Marra CA. Dietary lipids modify redox homeostasis and steroidogenic status in rat testis. Nutrition 2008; 24:717-26. [DOI: 10.1016/j.nut.2008.03.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 02/28/2008] [Accepted: 03/07/2008] [Indexed: 12/22/2022]
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Zaidenberg A, Marra C, Luong T, Gómez P, Milani L, Villagra S, Drut R. Trifluralin toxicity in a Chagas disease mouse model. Basic Clin Pharmacol Toxicol 2007; 101:90-5. [PMID: 17651308 DOI: 10.1111/j.1742-7843.2007.00079.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Even though trifluralin (alpha,alpha,alpha-2,6-dinitro-N-N-dipropyl-p-toluidine) is effective for the treatment of experimental Chagas disease, more preclinical toxicity studies need to be performed. Cell toxicity of trifluralin was studied in Hep-G2 and Vero C76 cells treated with 50 and 150 microM trifluralin. The results show that duplication time, amount of cellular protein and cell protein/DNA values were normal. Histological, haematological and chemical parameters were measured in CF1 mice after oral trifluralin administration. Acute toxic effects were assayed by administration of 50 or 200 mg/kg body weight daily for 30 days, and chronic effects by administration of 200 mg/kg body weight once a week for 90 days (n = 20). In the acute scheme treatment, hepatic (glutamic-pyruvic, glutamic-oxalacetic and alkaline phosphatase activities; proteins and albumin plasma concentrations) and pancreatic (amylase, glycaemia) functions were normal. Mean corpuscular volume, haemoglobin and haematocrit decreased. Creatine phosphokinase, lactate dehydrogenase and glutamic-oxalacetic activity increased, suggesting lesion in myocardial tissue. Histology was normal, excepting for the heart (mild myocarditis). Similar results were observed in acutely treated animals. There were no differences in body weight gain for treated mice compared to controls. In view of the published therapeutic effects of trifluralin on CF1 Chagas disease model and considering the present results, trifluralin seems to be a moderately toxic drug with a potential selective effect on the myocardium.
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Affiliation(s)
- Aníbal Zaidenberg
- Institute of Pediatric Research and Development (La Plata Children's Hospital - Scientific Research Commission of the Province of Buenos Aires CICPBA), La Plata, Argentina.
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Portolesi R, Powell BC, Gibson RA. Competition between 24:5n-3 and ALA for Δ6 desaturase may limit the accumulation of DHA in HepG2 cell membranes. J Lipid Res 2007; 48:1592-8. [PMID: 17409318 DOI: 10.1194/jlr.m700081-jlr200] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The use of Delta 6 desaturase (D6D) twice in the conversion of alpha-linolenic acid (ALA; 18:3n-3) to docosahexaenoic acid (DHA; 22:6n-3) suggests that this enzyme may play a key regulatory role in the synthesis and accumulation of DHA from ALA. We examined this using an in vitro model of fatty acid metabolism to measure the accumulation of the long-chain metabolites of ALA in HepG2 cell phospholipids. The accumulation of ALA, eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3), and 24:5n-3 in cell phospholipids was linearly related to the concentration of supplemented ALA over the range tested (1.8-72 microM). The accumulation of the post-D6D products of 22:5n-3, 24:6n-3 and DHA, in cell phospholipids was saturated at concentrations of >18 microM ALA. Supplementation of HepG2 cells with preformed DHA revealed that, although the accumulation of DHA in cell phospholipids approached saturation, the level of DHA in cell phospholipids was significantly greater compared with the accumulation of DHA from ALA, indicating that the accumulation of DHA from ALA was not limited by incorporation. The parallel pattern of accumulation of 24:6n-3 and DHA in response to increasing concentrations of ALA suggests that the competition between 24:5n-3 and ALA for D6D may contribute to the limited accumulation of DHA in cell membranes.
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Affiliation(s)
- Roxanne Portolesi
- Department of Paediatrics and Child Health, Flinders University, Adelaide, Australia
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Maté SM, Layerenza JP, Ves-Losada A. Incorporation of arachidonic and stearic acids bound to L-FABP into nuclear and endonuclear lipids from rat liver cells. Lipids 2007; 42:589-602. [PMID: 17551764 DOI: 10.1007/s11745-007-3063-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Accepted: 04/09/2007] [Indexed: 10/23/2022]
Abstract
The incorporation of exogenous fatty acids bound to L-FABP into nuclei was studied. Rat liver cell nuclei and nuclear matrices (membrane depleted nuclei) were incubated in vitro with [1-(14)C]18:0 and 20:4n-6 either free or bound to L-FABP, ATP and CoA. FA esterification in whole nuclei and endonuclear lipids was ATP-CoA-dependent, and with specificity regarding fatty acid type and lipid class. 18:0 and 20:4n-6, free or L-FABP bound, showed the same incorporation and esterification pattern in lipids of whole nuclei. Only 20:4n-6 L-FABP bound was less incorporated into TAG with respect to free 20:4n-6. In the nuclear matrix, 18:0 free or L-FABP bound was esterified with a higher specific activity (SA) into: PtdEtn > PtdIns, PtdSer > PtdCho. 20:4n-6 free or L-FABP bound was esterified into: PtdIns > PtdEtn > PtdCho. 20:4n-6:L-FABP was esterified in endonuclear total-PL and PtdIns with a greater SA with respect to free 20:4n-6 and with a minor one as FFA. To summarize, trafficking of FA to nuclei includes esterification of 18:0 and 20:4n-6 either free or L-FABP-bound, into nuclear and endonuclear lipids by an ATP-CoA-dependent pathway. Endonuclear fatty acid esterification was more active than that in whole nuclei, and independent of the nuclear membrane. Esterification patterns of fatty acids L-FABP-bound or free into whole nuclear lipids were the same whereas in the nuclear matrix, L-FABP could play an important role in the mobilization of 20:4n-6 into specific sites of utilization such as the PtdIns pools.
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Affiliation(s)
- Sabina M Maté
- Facultad de Ciencias Médicas, Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-UNLP, 60 y 120, 1900 La Plata, Argentina
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Abstract
Lipids are not only components of cell nucleus membranes, but are also found in the membrane-depleted nuclei where they fulfill special functions. We have investigated the lipid composition of membrane-depleted rat liver nuclei obtained by incubation with low Triton X-100 concentrations of 0.04% and 0.08%, which rendered them unaltered or hardly altered. Under these conditions, 26% of proteins and 22% of phospholipids were recovered. The main phospholipids were phosphatidylcholine > phosphatidylethanolamine > phosphatidylinositol = or > phosphatidylserine and sphingomyelin (in decreasing concentrations). The fatty acid components of total lipids and phosphatidylcholine were mainly unsaturated. Over 40% belonged to the n-6 series (arachidonic > or = 25% and linoleic 15%); approximately 40% corresponded to saturated acids and <10% were monoenoic. Endonuclear phosphatidylcholine was built up by 16 molecular species, the most abundant being 18:0-20:4 (32%), 16:0-20:4 (19%), 16:0-18:2 (13%), and 18:0-18:2 (11%). The fatty acid composition and phosphatidylcholine molecular species distribution in the membrane-depleted nucleus of rat liver showed patterns similar to the whole nucleus, mitochondria, microsomes, and homogenate of the parent liver cells, suggesting that endonuclear lipid pool composition is mainly determined by a liver organ profile.
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Affiliation(s)
- Sabina M Maté
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Facultad de Ciencias Médicas, UNLP-CONICET, calles 60 y 120, Argentina
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Marra CA, de Alaniz MJT. Microtubular integrity differentially modifies the saturated and unsaturated fatty acid metabolism in cultured Hep G2 human hepatoma cells. Lipids 2006; 40:999-1006. [PMID: 16382571 DOI: 10.1007/s11745-005-1462-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The influence of cytoskeleton integrity on the metabolism of saturated and unsaturated FA was studied in surface cultures and cell suspensions of human Hep G2 hepatoma cells. We found that colchicine (COL), nocodazol, and vinblastin produced a significant inhibition in the incorporation of labeled saturated FA, whereas incorporation of the unsaturated FA remained unaltered. These microtubule-disrupting drugs also diminished Delta9-, Delta5-, and Delta6-desaturase capacities. The effects produced by COL were dose (0-50 microM) and time (0-300 min) dependent, and were antagonized by stabilizing agents (phalloidin and DMSO). Dihydrocytochalasin B (20 microM) was tested as a microfilament-disrupting drug and produced no changes in either the incorporation of [14C] FA or the desaturase conversion of the substrates. We hypothesized that the interactions between cytoskeleton and membrane proteins such as FA desaturases may explain the functional organization, facilitating both substrate channeling and regulation of unsaturated FA biosynthesis.
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Affiliation(s)
- Carlos A Marra
- Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
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Risé P, Ghezzi S, Priori I, Galli C. Differential modulation by simvastatin of the metabolic pathways in the n-9, n-6 and n-3 fatty acid series, in human monocytic and hepatocytic cell lines. Biochem Pharmacol 2005; 69:1095-100. [PMID: 15763545 DOI: 10.1016/j.bcp.2005.01.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Accepted: 01/12/2005] [Indexed: 11/21/2022]
Abstract
Statins affect the production of long chain polyunsaturated fatty acids (PUFA), both in vitro and in vivo. Various studies have shown the effects of statins on the pattern of n-6 fatty acids (FA), but limited attention has been paid to the n-3 FA. We investigated, in THP-1 and in HepG2 cells, the effects of simvastatin on the conversion of the 18C FA precursors in the n-3 and n-6 series, [1-(14)C] alpha-linolenic acid (alpha-LNA) and [1-(14)C] linoleic acid (LA) respectively, and on the metabolism of [1-(14)C] stearic acid (SA). THP-1 cells, as in the case of LA, actively converted alpha-LNA to its products, and after simvastatin treatment, the total conversion was significantly increased (from 57.2+/-7.2 to 74.3+/-8.5%, p<0.05). HepG2 cells also converted LA and alpha-LNA, but simvastatin increased significantly only the conversion of LA (9.5+/-1.9% versus 23.8+/-5.1%, p<0.02). SA conversion was similar in untreated cells (about 50%), while statin increased the production of oleic acid in HepG2, but in THP-1 cells there was a decrease. In conclusion, LA, alpha-LNA and SA are differentially metabolized in THP-1 and in HepG2 cells and their increased conversion by simvastatin is lower in HepG2 than in THP-1. These differences may reflect the distinct features of the two cell lines: monocytes, precursors of phagocytic cells, versus hepatocytes with mainly metabolic functions. Substantial differences concern also cellular FA pools: structural in THP-1 cells, and also depot, resulting in sequestering of the substrates, in HepG2. The greater n-3 FA metabolism in THP-1 cells may have favourable functional effects.
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Affiliation(s)
- Patrizia Risé
- Department of Pharmacological Sciences, University of Milan, via Balzaretti 9, 20133 Milan, Italy.
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Chamras H, Ardashian A, Heber D, Glaspy JA. Fatty acid modulation of MCF-7 human breast cancer cell proliferation, apoptosis and differentiation. J Nutr Biochem 2002; 13:711-716. [PMID: 12550055 DOI: 10.1016/s0955-2863(02)00230-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epidemiological studies suggest that dietary polyunsaturated fatty acids (PUFA) may influence breast cancer progression and prognosis. In order to study potential mechanisms of action of fatty acid modulation of tumor growth, we studied, in vitro, the influence of n-3 and n-6 fatty acids on proliferation, cell cycle, differentiation and apoptosis of MCF-7 human breast cancer cells. Both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) inhibited the MCF-7 cell growth by 30% and 54%, respectively, while linoleic acid (LA) had no effect and arachidonic acid (AA) inhibited the cell growth by 30% (p < 0.05). The addition of vitamin E (10uM) to cancer cells slightly restored cell growth. The incubation of MCF-7 cells with PUFAs did not alter the cell cycle parameters or induce cell apoptosis. However, the growth inhibitory effects of EPA, DHA and AA were associated with cell differentiation as indicated by positive Oil-Red-O staining of the cells. Lipid droplet accumulation was increased by 65%, 30% and 15% in the presence of DHA, EPA and AA, respectively; (p < 0.05). These observations suggest that fatty acids may influence cellular processes at a molecular level, capable of modulating breast cancer cell growth.
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Affiliation(s)
- Hilda Chamras
- Division of Hematology/Oncology and Center for Human Nutrition, Department of Medicine, UCLA, Los Angeles, California, USA
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20
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Fu XY, Wang HY, Tan L, Liu SQ, Cao HF, Wu MC. Overexpression of p28/ gankyrin in human hepatocellular carcinoma and its clinical significance. World J Gastroenterol 2002; 8:638-43. [PMID: 12174370 PMCID: PMC4656312 DOI: 10.3748/wjg.v8.i4.638] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the expression of p28/gankyrin gene and its role in the carcinogenetic process of human hepatocellular carcinoma (HCC).
METHODS: 64 specimens of HCC and para-carcinoma tissues, 22 specimens of non-tumor liver tissues (7 normal, 15 cirrhosis), 10 specimens of normal human tissues and 5 hepatoma cell lines were studied for the expression of p28/gankyrin by Northern blot. The expression of p28/gankyrin protein was detected immunohistochemically by using the specific polyclonal antibody.
RESULTS: Northern blot analysis indicated that the expression of p28/gankyrin mRNA was intensively distributed in brain and heart, weakly in lung, spleen and muscle, undetectable in digestive system including liver, pancreas, stomach, small and large intestines. p28/gankyrin mRNA was absent in normal liver, weakly detected in liver cirrhosis and in 18 of 64 para-carcinoma liver tissues. In contrast, the expression of p28/gankyrin mRNA was intensively detected in all 5 hepatoma cell lines tested, markedly increased in 57 of 64 and moderately increased in 5 of 64 HCC samples. In comparison with liver cirrhosis and para-carcinoma liver tissues, the average expression of p28/gankyrin mRNA in HCC was increased 3.6- (2.901 ± 0.507 vs 0.805 ± 0.252, P < 0.05) and 5.2-fold (2.901 ± 0.507 vs 0.557 ± 0.203, P < 0.01), respectively. In addition, p28/gankyrin mRNA expression level was higher in HCC with portal vein tumor thrombus and microscopic hepatic vein involvement (P = 0.021 and P = 0.047, respectively). The overexpression of p28/gankyrin protein in HCC was targeted in hepatic tumor cells, not in bile duct cells and other interstitial cells.
CONCLUSION: Overexpression of p28/gankyrin in HCC plays an important role and contributes to the metastasis potential in the process of carcinogenesis. p28/gankyrin may become a specific biological tissue marker for the pathological diagnosis of HCC.
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Affiliation(s)
- Xiao-Yong Fu
- International Co-operation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Second Military Medical University, 200438, Shanghai, China
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21
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Marra CA, Zaidenberg A, de Alaniz MJT, Buschiazzo H. The restoring effect of trifluralin and benznidazole on the abnormal fatty-acid pattern induced by Trypanosoma cruzi in the liver microsomes of infected mice. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2002; 96:249-64. [PMID: 12061972 DOI: 10.1179/000349802125000781] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The fatty-acid composition of liver lipids from mice infected with Trypanosoma cruzi (clone H510C8C3) or uninfected mice was investigated. The infected animals were treated orally for 30 days, with trifluralin (TFL) or benznidazole (BNZ), each at 100mg/kg.day, or only with the peanut oil used as the drug vehicle. The uninfected mice were also given the peanut oil. The treatments were stopped 10 days before the animals were killed. The liver microsomal lipids of each mouse were isolated and then analysed by gas-liquid chromatography. In terms of the total lipids, untreated infection evoked a significant increase in saturated fatty acids and the members of the n-9 fatty-acid family, with a concomitant decrease in the polyenoates of the n-3 and n-6 fatty-acid series. Each lipid subclass was affected to a different extent, the phospholipids being affected most. All lipid fractions, apart from the cholesterol esters, showed a significant increase in the proportion of n-9 isomers. Infection also produced a marked increase in the absolute amounts of triacylglycerides, cholesterol and cholesterol esters in liver microsomal membranes. After BNZ or TFL treatment, the fatty-acid pattern of mice that had been infected was indistinguishable from that of the control mice. The possible role of desaturase activity in the alterations observed is discussed.
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Affiliation(s)
- C A Marra
- INIBIOLP (Instituto de Investigaciones Bioquímicas de La Plata), Cátedra de Bioquímica, Universidad Nacional de La Plata, Calle 60 y 120, 1900, Argentina.
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22
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Marra CA, Girón MD, Suáre MD. Evidence in favor of a facilitated transport system for FA uptake in cultured L6 cells. Lipids 2002; 37:273-83. [PMID: 11942478 DOI: 10.1007/s11745-002-0891-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In this manuscript we report a study of the transport of FA in L6 muscle cells. Cultured L6 cells took up labeled FA (C10 to C20) as a linear function of time up to 15 min. Thereafter, the rate of uptake gradually declined although it persisted for at least 12 h after the addition of the substrate. Kinetic parameters (Km, Vm, and k(o)) were determined from a fitted Michaelis-Menten-type equation modified by a term for a saturable (linear) component of the measured total uptake. Vm values were different for some of the FA studied, and Km data showed significant differences between saturated and unsaturated FA. The maximal rate of uptake was observed at pH 7.40 for decanoate, palmitate, and eicosatrienoate. Uptake was significantly influenced when the pH of the incubation medium was changed. Experiments designed to study the influence of FA/albumin molar ratio indicated that Vm was dependent on the total (bound and free) concentration of the FA. A concentrative uptake was demonstrated in short-term experiments with an apparent plateau of 20 and 40 microM for palmitate and eicosatrienoate, respectively. A competitive inhibition was also observed between palmitate as substrate and the other FA. From our results we can postulate that the uptake of FA in L6 cells is the sum of passive diffusion plus a saturable component and that the rate of uptake is dependent on one (or more) protein structures, although their precise characteristics and functions remain to be elucidated.
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Affiliation(s)
- Carlos A Marra
- INIBIOLP Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
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Albino L, Polo MP, de Bravo MG, de Alaniz MJ. Uptake and metabolic conversion of saturated and unsaturated fatty acids in Hep2 human larynx tumor cells. Prostaglandins Leukot Essent Fatty Acids 2001; 65:295-300. [PMID: 11993723 DOI: 10.1054/plef.2001.0328] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Research on fatty acid metabolism in cultured human larynx tumor cells Hep2 was carried out. The cells were incubated with either a saturated (palmitic) or a polyunsaturated (linoleic, alpha-linolenic and eicosatrienoic (n-6)) radioactive fatty acid (0.66 pM, 24 h). The best incorporation capacity was observed in the linoleic acid followed by alpha-linolenic, palmitic and eicosatrienoic acids. All fatty acids tested were anabolized to higher derivatives within their own family. Palmitic acid was primarily monodesaturated rather than elongated, proving to have a very active A9 desaturase activity. With respect to polyunsaturated acid metabolism, the conversion of alpha-linolenic acid to higher homologs, although better than linoleic acid, occurred far less efficiently than that observed in other non-highly undifferentiated human tumor cells. This impairment in higher polyunsaturated fatty acid biosynthesis, reflected in the low levels of arachidonic acid in the fatty acid composition, would not reside in the A5 desaturation step since Hep2 cells can readily convert eicosatrienoic acid into arachidonic acid. Considering the potential regulatory role of specific polyunsaturated fatty acids in the cell proliferative control, the knowledge of the metabolism of fatty acids in this human tumor cell would be important for designing future experiments in order to clarify the mechanism involved in balance, proliferation and cell death.
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Affiliation(s)
- L Albino
- Instituto de Investigaciones Bioquimicas de La Plata (INIBIOLP), CONICET-UNLP, Facultad de Ciencias Medicas, Argentina
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24
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Marra CA, de Alaniz MJ. Calcium deficiency modifies polyunsaturated fatty acid metabolism in growing rats. Lipids 2000; 35:983-90. [PMID: 11026619 DOI: 10.1007/s11745-000-0609-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fatty acid desaturase activities were determined in liver microsomes from calcium-deficient rats and compared to calcium-sufficient ones. The calcium-deprived diet (0.5 g/kg) administered for 60 d caused a 30% inhibition in the delta5 desaturase activity and a 45-55% decrease in delta6 and delta9, respectively, facts that cannot be attributed to a reduction in food intake. In vitro addition of calcium, ethyleneglycol-bis(Beta-aminoethyl ether)N,N-tetraacetic acid, and/or cytosol fractions from control or calcium-deficient rats to microsomes from both groups of animals indicates that the reduced desaturase capacities would be the consequence of an indirect effect of calcium deprivation. The present work shows that the reduced unsaturated fatty acid biosynthesis might be the result of modifications in the physicochemical properties of microsomal membranes. Such changes could also be derived from the inhibition of phospholipase A2 activity induced by calcium deficiency.
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Affiliation(s)
- C A Marra
- Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
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25
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Louw L, Engelbrecht AM, Cloete F. Comparison of the fatty acid compositions in intraepithelial and infiltrating lesions of the cervix: part I, total fatty acid profiles. Prostaglandins Leukot Essent Fatty Acids 1998; 59:247-51. [PMID: 9849650 DOI: 10.1016/s0952-3278(98)90137-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In the first part of this study, the possible role of essential total fatty acids and their metabolites during cervical carcinogenesis was investigated. Since membrane lipids play a key role in cell proliferation and differentiation, disturbances in the fatty acid compositions of cell membranes and the modulation of membrane fatty acid compositions received attention in several in vitro studies. There are, however, no reported studies where the actual total and free (unesterified) fatty acid compositions have been determined during the different stages of cervical carcinogenesis. In part I of this ex vivo study, the total fatty acid compositions of normal tissue, intraepithelial and infiltrating lesions of the cervix were compared. The fatty acid profiles that were determined make it possible to speculate about the metabolic pathways followed during cervical carcinogenesis. Lipids were extracted from biopsies of normal tissue (n=36), cervical intraepithelial lesions (n=47) and infiltrating lesions (n=47). Samples, from which the total fatty acid compositions were determined, were saponified, methylated and analysed by gas liquid chromatography (GLC). Essential fatty acid deficiency (EFAD) in the intraepithelial lesions, compared with normal tissue (linoleic acid, P< 0.01), and infiltrating lesions, compared with intraepithelial lesions (linoleic acid and arachidonic acid, P< 0.01) were observed. High levels of oleic acid were also observed when infiltrating lesions were compared with normal tissue (P< 0.01). This EFAD in cancer cells may result in many defective cell mechanisms. Although there are many risk factors for cervical cancer, the human papilloma virus has emerged over the past decade as the leading candidate to be an aetiological factor. There is ample evidence that human viral infections are associated with reduced levels of linoleic acid and thus participate in the depletion of essential fatty acids in cancer cells.
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Affiliation(s)
- L Louw
- Department of Anatomy and Cell Morphology, Faculty of Health Sciences, University of the Orange Free State, Bloemfontein, South Africa
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26
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Tocher DR, Leaver MJ, Hodgson PA. Recent advances in the biochemistry and molecular biology of fatty acyl desaturases. Prog Lipid Res 1998; 37:73-117. [PMID: 9829122 DOI: 10.1016/s0163-7827(98)00005-8] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- D R Tocher
- NERC Unit of Aquatic Biochemistry, School of Natural Sciences, University of Stirling, Scotland, U.K
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27
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de Antueno R, Elliot M, Ells G, Quiroga P, Jenkins K, Horrobin D. In vivo and in vitro biotransformation of the lithium salt of gamma-linolenic acid by three human carcinomas. Br J Cancer 1997; 75:1812-8. [PMID: 9192987 PMCID: PMC2223625 DOI: 10.1038/bjc.1997.309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Lipid metabolism has been considered recently as a novel target for cancer therapy. In this field, lithium gamma-linolenate (LiGLA) is a promising experimental compound for use in the treatment of human tumours. In vivo and in vitro studies allowed us to assess the metabolism of radiolabelled LiGLA by tumour tissue and different organs of the host. In vitro studies demonstrated that human pancreatic (AsPC-1), prostatic (PC-3) and mammary carcinoma (ZR-75-1) cells were capable of elongating GLA from LiGLA to dihomo-gamma-linolenic acid (DGLA) and further desaturating it to arachidonic acid (AA). AsPC-1 cells showed the lowest delta5-desaturase activity on DGLA. In the in vivo studies, nude mice bearing the human carcinomas were given Li[1-(14)C]GLA (2.5 mg kg(-1)) by intravenous injection for 30 min. Mice were either sacrificed after infusion or left for up to 96 h recovery before sacrifice. In general, the organs showed a maximum uptake of radioactivity 30 min after the infusion started (t = 0). Thereafter, in major organs the percentage of injected radioactivity per g of tissue declined below 1% 96 h after infusion. In kidney, brain, testes/ovaries and all three tumour tissues, labelling remained constant throughout the experiment. The ratio of radioactivity in liver to tumour tissues ranged between 16- and 24-fold at t = 0 and between 3.1- and 3.7-fold at 96 h. All tissues showed a progressive increase in the proportion of radioactivity associated with AA with a concomitant decrease in radiolabelled GLA as the time after infusion increased. DGLA declined rapidly in liver and plasma, but at a much slower rate in brain and malignant tissue. Seventy-two hours after the infusion, GLA was only detected in plasma and tumour tissue. The sum of GLA + DGLA varied among tumour tissues, but it remained 2-4 times higher than in liver and plasma. In brain, DGLA is the major contributor to the sum of these fatty acids. Data showed that cytotoxic GLA and DGLA, the latter provided either by the host or by endogenous synthesis, remained in human tumours for at least 4 days.
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Affiliation(s)
- R de Antueno
- Scotia Research Institute, Kentville, NS, Canada
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28
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Angeletti C, de Alaniz MJ. Fatty acid uptake and metabolism in Hep G2 human-hepatoma cells. Mol Cell Biochem 1995; 143:99-105. [PMID: 7596353 DOI: 10.1007/bf01816942] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of this work was to study the fatty acid metabolism of the human-hepatoma cell line Hep G2. The cultured cells were incubated with either a saturated (palmitic, stearic) or a polyunsaturated (linoleic, alpha-linolenic, eicosatrienoic n-6) radioactive fatty acid. The fatty acids were incorporated into all the basic lipid classes as well as into the main phospholipid subclasses in the cellular membranes. All the fatty acids tested provided a source of carbon for lower members of the saturated fatty-acid family or for cholesterol through beta-oxidation and a new cycle of de novo synthesis. Moreover, all radioactive fatty-acid precursors, whether saturated or unsaturated, were anabolized to higher derivatives within their own family. In the case of saturated fatty acids, palmitic and stearic, they were readily monodesaturated to their corresponding products, thus demonstrating the presence of a delta 9 desaturase. Linoleate and alpha-linolenate were both desaturated and elongated to all the subsequent members of their respective n-6 and n-3 families. These latter observations provide evidence for the incidence of desaturation at the 6 and 5 positions along with the existence of an elongating capacity for fatty acids of all families and chain lengths. In addition, the cellular steady-state fatty-acid profile was seen to be significantly different from the spectrum of exogenous fatty acids available in the growth medium. We conclude that the Hep G2 human-hepatoma line represents an appropriate and relevant experimental model system for investigating the fatty-acid metabolism of adult human liver in vivo.
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Affiliation(s)
- C Angeletti
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-UNLP, Facultad de Ciencias Médicas, Argentina
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29
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Grammatikos SI, Subbaiah PV, Victor TA, Miller WM. Diversity in the ability of cultured cells to elongate and desaturate essential (n-6 and n-3) fatty acids. Ann N Y Acad Sci 1994; 745:92-105. [PMID: 7832535 DOI: 10.1111/j.1749-6632.1994.tb44366.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Essential fatty acids (EFAs) cannot be synthesized by mammalian cells. Once taken in with the diet, they can undergo desaturations/saturations and chain elongations/shortenings to yield a variety of polyunsaturated fatty acids of the same family. Cells in vitro from a variety of tissues are capable of processing EFAs to varying extents. Conversion of the parent EFAs, linoleic (LA, n-6) and alpha-linolenic (LNA, n-3) acids, to the 20-carbon polyunsaturated fatty acids, arachidonic (AA, n-6) and eicosapentanoic (EPA, n-3), requires chain elongation and delta 6 and delta 5 desaturations. AA and EPA are required by many tissues for optimal biological function and are precursors of biologically active eicosanoid hormones. All cultured cells are able to elongate exogenous LA and LNA, and most can perform delta 5 desaturation, so delta 6 desaturation is the limiting step in AA and EPA production. Longer fatty acids that have more double bonds than AA or EPA are less frequently produced due to a deficiency in delta 4 desaturating ability. The process of retroconversion (chain shortening) is less extensively studied, but evidence from a variety of cells suggests that this type of metabolic conversion is normally active. The example of MCF-7 (human breast cancer cell line) and MCF-10A cells (human noncancerous breast cell line) is discussed in order to emphasize the diversity in EFA processing ability of cultured cells. Under identical culture conditions, MCF-10A cells perform extensive desaturations, elongations, and retroconversions, whereas MCF-7 cells can only elongate and retroconvert exogenous EFAs. Given the great diversity in the ability of cultured cells to process EFAs, no conclusions can be drawn regarding the mechanisms responsible for the effects of exogenous EFAs on a particular cell until that cell's EFA processing patterns have been evaluated.
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Affiliation(s)
- S I Grammatikos
- Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208-3120
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30
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de Alaniz MJ, Marra CA. Role of delta 9 desaturase activity in the maintenance of high levels of monoenoic fatty acids in hepatoma cultured cells. Mol Cell Biochem 1994; 137:85-90. [PMID: 7845382 DOI: 10.1007/bf00926043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The incorporation and delta 9 desaturation of exogenous [14C]stearic acid were studied in HTC 7288c cells in suspension. We examined the uptake of the acid over a wide range of concentrations (0-160 microM) after incubating the cells for 6 h in a chemically-defined medium. Under this experimental condition, the uptake of the labeled acid was more extensive than that obtained from static cultures or from monolayer of isolated hepatocytes of rats. At an external concentration of 160 microM ca. 52 nmoles of acid per mg of cellular protein was taken up. The production of oleic acid from [14C]stearate (delta 9 desaturation) correlated well with the uptake curve between 0-80 microM concentration. For higher stearate concentrations, the biosynthesis of oleic acid declined substantially and a plateau of 22 nmoles/mg cellular protein was reached. The incorporation and desaturation of an initial exogeneous concentration of [14C]stearic acid (80 microM) was also studied from 0-6 h. The results obtained demonstrated that the uptake of the substrate into cellular lipids was fast and non saturable. Quantitative gas-liquid chromatography of total cellular lipids under the different experimental conditions demonstrated a negative correlation between the decrease in the palmitic and palmitoleic acids and the increase in the intracellular levels of stearic and oleic acids. These analytical modifications took place with no changes in the saturated/monoenoic fatty acid ratio. This work also demonstrated a significant contribution of the stearoyl-CoA desaturase system to the high levels of oleic acid present in this kind of hepatoma cells.
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Affiliation(s)
- M J de Alaniz
- INIBIOLP (Institut de Investigaciones Bioquímicas de La Plata), UNLP-CONICET, Facultad de Ciencias Médicas, La Plata, Argentina
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31
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Grammatikos SI, Subbaiah PV, Victor TA, Miller WM. n-3 and n-6 fatty acid processing and growth effects in neoplastic and non-cancerous human mammary epithelial cell lines. Br J Cancer 1994; 70:219-27. [PMID: 8054269 PMCID: PMC2033515 DOI: 10.1038/bjc.1994.283] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The type rather than the amount of dietary fat may be more important in breast carcinogenesis. While animal studies support this view, little is known about the effects of essential fatty acids (EFAs) at the cellular level. The MCF-7 breast cancer and the MCF-10A non-cancerous human mammary epithelial cell lines are compared in terms of growth response to EFAs and ability to incorporate and process the EFAs. Eicosapentaenoic (EPA, n-3) and docosahexaenoic (DHA, n-3) acids, presented bound to albumin, inhibited the growth of MCF-7 cells by as much as 50% in a dose-dependent manner (6-30 microM) in medium containing 0.5% serum. alpha-Linolenic (LNA, n-3) and arachidonic (AA, n-6) acids inhibited growth less extensively, while linoleic acid (LA, n-6) had no effect. In contrast, MCF-10A cells were not inhibited by any of the EFAs at levels below 24 microM. The differential effects of AA, EPA and DHA on MCF-7 and MCF-10A cells support a protective role of highly unsaturated essential fatty acids against breast cancer. The EFAs were primarily incorporated into phosphoglycerides. MCF-7 cells showed chain elongations and possibly delta 8 desaturation, but no AA was formed from LA, nor EPA or DHA from LNA. In contrast, MCF-10A cells desaturated and elongated the exogenous EFAs via all the known pathways. These findings suggest defects in the desaturating enzymes of MCF-7 cells. LNA, DHA and AA presented to MCF-7 cells in phospholipid liposomes inhibited growth as extensively as albumin-bound free acids, but were less extensively incorporated, suggesting different mechanisms of inhibition for the two methods.
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Affiliation(s)
- S I Grammatikos
- Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208-3120
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32
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Grammatikos SI, Subbaiah PV, Victor TA, Miller WM. Diverse effects of essential (n-6 and n-3) fatty acids on cultured cells. Cytotechnology 1994; 15:31-50. [PMID: 7765945 DOI: 10.1007/bf00762377] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Fatty acids (FAs) have long been recognized for their nutritional value in the absence of glucose, and as necessary components of cell membranes. However, FAs have other effects on cells that may be less familiar. Polyunsaturated FAs of dietary origin (n-6 and n-3) cannot be synthesized by mammals, and are termed 'essential' because they are required for the optimal biologic function of specialized cells and tissues. However, they do not appear to be necessary for normal growth and metabolism of a variety of cells in culture. The essential fatty acids (EFAs) have received increased attention in recent years due to their presumed involvement in cardiovascular disorders and in cancers of the breast, pancreas, colon and prostate. Many in vitro systems have emerged which either examine the role of EFAs in human disease directly, or utilize EFAs to mimic the in vivo cellular environment. The effects of EFAs on cells are both direct and indirect. As components of membrane phospholipids, and due to their varying structural and physical properties, EFAs can alter membrane fluidity, at least in the local environment, and affect any process that is mediated via the membrane. EFAs containing 20 carbons and at least three double bonds can be enzymatically converted to eicosanoid hormones, which play important roles in a variety of physiological and pathological processes. Alternatively, EFAs released into cells from phospholipids can act as second messengers that activate protein kinase C. Furthermore, susceptibility to oxidative damage increases with the degree of unsaturation, a complication that merits consideration because lipid peroxidation can lead to a variety of substances with toxic and mutagenic properties. The effects of EFAs on cultured cells are illustrated using the responses of normal and tumor human mammary epithelial cells. A thorough evaluation of EFA effects on commercially important cells could be used to advantage in the biotechnology industry by identifying EFA supplements that lead to improved cell growth and/or productivity.
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Affiliation(s)
- S I Grammatikos
- Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208-3120
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