Fatty acid-induced toxicity and neutral lipid accumulation in insulin-producing RINm5F cells

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

The melatonin receptor agonist agomelatine protects against acute pancreatitis induced by cadmium by attenuating inflammation and oxidative stress and modulating Nrf2/HO-1 pathway

Pancreatitis is a serious effect of the heavy metal cadmium (Cd) and inflammation and oxidative stress (OS) are implicated in Cd-induced pancreatic injury. This study evaluated the effect of the melatonin receptor agonist agomelatine (AGM) on Cd-induced acute pancreatitis (AP), pointing to its modulatory effect on inflammation, OS, and Nrf2/HO-1 pathway. Rats were supplemented with AGM orally for 14 days and a single injection of cadmium chloride (CdCl2) on day 7. Cd increased serum amylase and lipase and caused pancreatic endocrine and exocrine tissue injury. Malondialdehyde (MDA), nitric oxide (NO) and myeloperoxidase (MPO) were elevated, nuclear factor (NF)-kB p65, inducible NO synthase (iNOS), interleukin (IL)-6, tumor necrosis factor (TNF)-α and CD40 were upregulated, and antioxidants were decreased in the pancreas of Cd-administered rats. AGM ameliorated serum amylase and lipase and pancreatic OS, NF-kB p65, CD40, pro-inflammatory mediators and caspase-3, prevented tissue injury and enhanced antioxidants. AGM downregulated Keap1 and enhanced Nrf2 and HO-1 in the pancreas of Cd-administered rats. In silico findings revealed the binding affinity of AGM with Keap1, HO-1, CD40L and caspase-3. In conclusion, AGM protected against AP induced by Cd by preventing inflammation, OS and apoptosis and modulating Nrf2/HO-1 pathway.

Renal Lipid Metabolism Abnormalities in Obesity and Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma is the most common and deadly type of cancer affecting the kidney, and is characterized histologically by large intracellular lipid deposits. These deposits are thought to result from lipid metabolic reprogramming occurring in tumor cells, but the exact mechanisms and implications of these metabolic alterations are incompletely understood. Obesity is an independent risk factor for clear cell renal cell carcinoma, and is also associated with lipid accumulation in noncancerous epithelial cells of the proximal tubule, where clear cell renal cell carcinoma originates. This article explores the potential link between obesity-associated renal lipid metabolic disturbances and lipid metabolic reprogramming in clear cell renal cell carcinoma, and discusses potential implications for future research.

Calcium channel blockers do not protect against saturated fatty acid-induced ER stress and apoptosis in human pancreatic β-cells

It was evidenced that saturated fatty acids (FAs) have a detrimental effect on pancreatic β-cells function and survival, leading to endoplasmic reticulum (ER) calcium release, ER stress, and apoptosis. In the present study, we have tested the effect of three calcium influx inhibitors, i.e., diazoxide, nifedipine, and verapamil, on the apoptosis-inducing effect of saturated stearic acid (SA) in the human pancreatic β-cell lines NES2Y and 1.1B4. We have demonstrated that the application of all three calcium influx inhibitors tested has no inhibitory effect on SA-induced ER stress and apoptosis in both tested cell lines. Moreover, these inhibitors have pro-apoptotic potential per se at higher concentrations. Interestingly, these findings are in contradiction with those obtained with rodent cell lines and islets. Thus our data obtained with human β-cell lines suggest that the prospective usage of calcium channel blockers for prevention and therapy of type 2 diabetes mellitus, developed with the contribution of the saturated FA-induced apoptosis of β-cells, seems rather unlikely.

Toxic Effects of Docosahexaenoic Acid Treatment in the Rat Liver BRL-3A Cell

The cytotoxicity of docosahexaenoic acid (DHA) on normal cells is still unclear. This study investigated the effects of DHA on the cytotoxicity and possible mechanism in the BRL-3A cell. The cultured rat liver BRL-3A cell line was treated with 50, 100 and 200 μM DHA for 24 h. The cell viability was increased in the 50 and 100 μM DHA treatments, but decreased in the 200 μM DHA treatment. The 50, 100 and 200 μM DHA treatments increased the proportion of the apoptotic cells, the levels of lactate dehydrogenase (LDH), alkaline phosphatase (AKP) and IL-6 in the supernatant, and the ratio of the phosphonated p38MAPK to the p38MAPK (p-p38/p38) protein in the cells. The expression of TGF beta-activated kinase 1 (TAK1), nuclear transcription factor-κB p65 (NF-κB p65) and the inhibitor of NF-κB alpha (IκBα) mRNA, and the ratio of the phosphonated IκBα (p-IκBα) to IκBα protein were increased in the 200 μM DHA treatment, while the ratio of phosphonated extracellular regulated protein kinases (p-ERK) to ERK protein was decreased in the 200 μM DHA treatment. These results indicate that DHA-treated (50, 100 and 200 μM) BRL-3A cells for 24 h promotes cell apoptosis and inflammatory response, and the p38 MAPK, ERK and NF-κB signal pathways were involved in mediating the apoptosis and inflammatory response.

Comparative transcriptomics of toxin synthesis genes between the non-toxin producing dinoflagellate Cochlodinium polykrikoides and toxigenic Alexandrium pacificum

In the present study, we extensively characterized potential toxin-related genes, including polyketide synthase (PKS), saxitoxin (STX) and fatty acid synthase (FAS) from the non-toxin producing marine dinoflagellate Cochlodinium polykrikoides, comparing to those of a toxigenic dinoflagellate Alexandrium pacificum. RNA sequencing revealed 50 and 271 PKS contigs from C. polykrikoides and A. pacificum, respectively. According to domain constitute and amino acid alteration, we further classified the dinoflagellate type I PKS genes into 4 sub-groups. Type III PKS was first identified in C. polykrikoides. Interestingly, we detected a large number (242 and 288) of homologs of 18 sxt genes from two studied dinoflagellates. Most of the eight key genes (sxtA, sxtB, sxtD, sxtG, sxtH/T, sxtI, sxtS and sxtU) for STX synthesis were detected in both dinoflatellates, whereas a core STX biosynthesis gene sxtG was not detected in C. polykrikoides. This may partially explain the absence of saxitoxin production in C. polykrikoides. In addition, we identified several type I and type II FAS genes, including FabD, FabF, FabG, FabH, FabI, and FabZ, whereas FabB was not found in C. polykrikoides. Overall, the numbers of the toxin-related genes in C. polykrikoides were less than that of A. pacificum. Phylogenetic analyses showed that type I PKS/FASs of dinoflagellates had close relationships with apicomplexans and bacteria. These suggest that the toxin-related PKS and sxt genes are commonly present in toxigenic and non-toxin producing dinoflagellates, and may be involved not only in the toxin synthesis, but also in other related molecular metabolic functions.

Impact of covalently Nile Red and covalently Rhodamine labeled fluorescent polymer micelles for the improved imaging of the respective drug delivery system

Novel fluorescently labeled poly(ethylene glycol)-poly(hydroxyoctanoic acid) (MPEG-PHOA) block-copolymers were synthesized for the improved visualization of the deriving polymeric micelle drug delivery system. Albeit commonly used, one has to be aware that by simple incorporation of Nile Red (hydrophobic) or Rhodamine B (hydrophilic) as fluorescent compounds in nanocarriers (e.g., nanoparticles, liposomes or micelles) for imaging applications, these fluorescent probes can diffuse out of the carrier system and lead to artefacts due to the concomitant fluorescence loss or areal distribution. In order to inhibit such an uncontrolled diffusion, the Nile Red derivative 2-((9-(diethylamino)-5-oxo-5H-benzo[a]phenoxazin-2-yl)oxy)acetic acid was synthesized and covalently attached to the MPEG-PHOA block-copolymer via a mild Mitsunobu reaction to yield the desired MPEG-PHOA-Nile Red polymer for micelle preparations. Rhodamine B was coupled via its native carboxylic acid group with the copolymer MPEG-PHOA under mild conditions using DMAP, EDC, and NHS. For the proof of concept, aqueous solutions of composite micelles made of 0.5% (w/w fluorescence dye) MPEG-PHOA-dye and MPEG-PHOA copolymers were prepared ("spiking" of the non-labeled base MPEG-PHOA micelles) and characterized by transmission electron microscopy (TEM), dialysis and fluorescence spectrometry. The fluorescence intensity of the Nile Red in the solutions was followed up at physiological temperatures and pH values (37 °C, pH = 7.4 PBS buffer 0.01 M) over a period of 8 weeks. The labeled and non-labeled micelle formulations were tested in vitro in cells (Rhodamine-micelle formulations), then in vivo in a case study of an ophthalmic application (Nile Red micelle formulations). Both in vitro and in vivo experiments revealed a significant improvement of fluorescence stability of the MPEG-PHOA-dye formulations, facilitating the investigations on tracing the micelles and their stability. The results clearly demonstrate the value of the novel Nile Red and Rhodamine derivatives, whose simple synthesis and covalent attachment may easily be transferred to other nanosized polymeric drug delivery systems, e.g., MPEGylated or non-MPEGylated PLA/PLGA nanoparticles and be envisioned for novel theranostic systems.

Sonodynamic therapy inhibits palmitate-induced beta cell dysfunction via PINK1/Parkin-dependent mitophagy

In type 2 diabetes mellitus (T2DM), the overload of glucose and lipids can promote oxidative stress and inflammatory responses and contribute to the failure of beta cells. However, therapies that can modulate the function of beta cells and thus prevent their failure have not been well explored. In this study, beta cell injury model was established with palmitic acid (PA) to simulate the lipotoxicity (high-fat diet) found in T2DM. Sonodynamic therapy (SDT), a novel physicochemical treatment, was applied to treat injured beta cells. We found that SDT had specific effects on mitochondria and induced transient large amount of mitochondrial reactive oxygen species (ROS) production in beta cells. SDT also improved the morphology and function of abnormal mitochondria, inhibited inflammatory response and reduced beta cell dysfunction. The improvement of mitochondria was mediated by PINK1/Parkin-dependent mitophagy. Additionally, SDT rescued the transcription of PINK1 mRNA which was blocked by PA treatment, thus providing abundant PINK1 for mitophagy. Moreover, SDT also increased insulin secretion from beta cells. The protective effects of SDT were abrogated when mitophagy was inhibited by cyclosporin A (CsA). In summary, SDT potently inhibits lipotoxicity-induced beta cell failure via PINK1/Parkin-dependent mitophagy, providing theoretical guidance for T2DM treatment in aspects of islet protection.

Fatty Acid-Stimulated Insulin Secretion vs. Lipotoxicity

Fatty acid (FA)-stimulated insulin secretion (FASIS) is reviewed here in contrast to type 2 diabetes etiology, resulting from FA overload, oxidative stress, intermediate hyperinsulinemia, and inflammation, all converging into insulin resistance. Focusing on pancreatic islet β-cells, we compare the physiological FA roles with the pathological ones. Considering FAs not as mere amplifiers of glucose-stimulated insulin secretion (GSIS), but as parallel insulin granule exocytosis inductors, partly independent of the K_ATP channel closure, we describe the FA initiating roles in the prediabetic state that is induced by retardations in the glycerol-3-phosphate (glucose)-promoted glycerol/FA cycle and by the impaired GPR40/FFA1 (free FA1) receptor pathway, specifically in its amplification by the redox-activated mitochondrial phospholipase, iPLA2γ. Also, excessive dietary FAs stimulate intestine enterocyte incretin secretion, further elevating GSIS, even at low glucose levels, thus contributing to diabetic hyperinsulinemia. With overnutrition and obesity, the FA overload causes impaired GSIS by metabolic dysbalance, paralleled by oxidative and metabolic stress, endoplasmic reticulum stress and numerous pro-apoptotic signaling, all leading to decreased β-cell survival. Lipotoxicity is exerted by saturated FAs, whereas ω-3 polyunsaturated FAs frequently exert antilipotoxic effects. FA-facilitated inflammation upon the recruitment of excess M1 macrophages into islets (over resolving M2 type), amplified by cytokine and chemokine secretion by β-cells, leads to an inevitable failure of pancreatic β-cells.

Effect of Saturated Stearic Acid on MAP Kinase and ER Stress Signaling Pathways during Apoptosis Induction in Human Pancreatic β-Cells Is Inhibited by Unsaturated Oleic Acid

It has been shown that saturated fatty acids (FAs) have a detrimental effect on pancreatic β-cells function and survival, leading to apoptosis, whereas unsaturated FAs are well tolerated and are even capable of inhibiting the pro-apoptotic effect of saturated FAs. Molecular mechanisms of apoptosis induction and regulation by FAs in β-cells remain unclear; however, mitogen-activated protein (MAP) kinase and endoplasmic reticulum (ER) stress signaling pathways may be involved. In this study, we tested how unsaturated oleic acid (OA) affects the effect of saturated stearic acid (SA) on the p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathways as well as the ER stress signaling pathways during apoptosis induction in the human pancreatic β-cells NES2Y. We demonstrated that OA is able to inhibit all effects of SA. OA alone has only minimal or no effects on tested signaling in NES2Y cells. The point of OA inhibitory intervention in SA-induced apoptotic signaling thus seems to be located upstream of the discussed signaling pathways.

Kinase Signaling in Apoptosis Induced by Saturated Fatty Acids in Pancreatic β-Cells

Pancreatic β-cell failure and death is considered to be one of the main factors responsible for type 2 diabetes. It is caused by, in addition to hyperglycemia, chronic exposure to increased concentrations of fatty acids, mainly saturated fatty acids. Molecular mechanisms of apoptosis induction by saturated fatty acids in β-cells are not completely clear. It has been proposed that kinase signaling could be involved, particularly, c-Jun N-terminal kinase (JNK), protein kinase C (PKC), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and Akt kinases and their pathways. In this review, we discuss these kinases and their signaling pathways with respect to their possible role in apoptosis induction by saturated fatty acids in pancreatic β-cells.

p38 MAPK Is Activated but Does Not Play a Key Role during Apoptosis Induction by Saturated Fatty Acid in Human Pancreatic β-Cells

Saturated stearic acid (SA) induces apoptosis in the human pancreatic β-cells NES2Y. However, the molecular mechanisms involved are unclear. We showed that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway in these cells. Therefore, we tested the role of p38 MAPK signaling pathway activation in apoptosis induction by SA in NES2Y cells. Crosstalk between p38 MAPK pathway activation and accompanying ERK pathway inhibition after SA application was also tested. The inhibition of p38 MAPK expression by siRNA silencing resulted in a decrease in MAPKAPK-2 activation after SA application, but it had no significant effect on cell viability or the level of phosphorylated ERK pathway members. The inhibition of p38 MAPK activity by the specific inhibitor SB202190 resulted in inhibition of MAPKAPK-2 activation and noticeable activation of ERK pathway members after SA treatment but in no significant effect on cell viability. p38 MAPK overexpression by plasmid transfection produced an increase in MAPKAPK-2 activation after SA exposure but no significant influence on cell viability or ERK pathway activation. The activation of p38 MAPK by the specific activator anisomycin resulted in significant activation of MAPKAPK-2. Concerning the effect on cell viability, application of the activator led to apoptosis induction similar to application of SA (PARP cleavage and caspase-7, -8, and -9 activation) and in inhibition of ERK pathway members. We demonstrated that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway and that this activation could be involved in apoptosis induction by SA in the human pancreatic β-cells NES2Y. However, this involvement does not seem to play a key role. Crosstalk between p38 MAPK pathway activation and ERK pathway inhibition in NES2Y cells seems likely. Thus, the ERK pathway inhibition by p38 MAPK activation does not also seem to be essential for SA-induced apoptosis.

Effect of NAD on PARP-mediated insulin sensitivity in oleic acid treated hepatocytes

High serum free fatty acids levels are associated with the development of insulin resistance in type 2 diabetes; however, the precise mechanisms underlying this lipid toxicity are unclear. To investigate whether PARP1 activation and NAD depletion are involved in the impairment of insulin sensitivity associated with lipotoxicity, HepG2 cells were cultured with 500 μM oleic acid for 48 h. Oleic acid-treated cells exhibited increased ROS generation, lipid accumulation and PARP1 activation. Treatment with the PARP1 inhibitor PJ34 and transfection with PARP1 small interfering RNA both prevented the oleic acid-induced impairment of the insulin signaling pathway. Furthermore, treatment with PJ34 reversed the oleic acid-induced decrease in intracellular NAD concentration, while exogenous NAD protected cells against oleic acid-induced insulin insensitivity. Combined NAD and PJ34 administration did not enhance the effects obtained by treatment with either NAD or PJ34 alone. Interestingly, when cells were treated with the SIRT1 inhibitor EX527, the protective effects of PJ34 and NAD treatment were diminished. Taken together, these data suggest that NAD depletion by PARP1 activation is essential for the modulation of insulin sensitivity in oleic acid-induced lipotoxicity.

The p66(Shc) redox adaptor protein is induced by saturated fatty acids and mediates lipotoxicity-induced apoptosis in pancreatic beta cells

AIMS/HYPOTHESIS

The role of the redox adaptor protein p66(Shc) as a potential mediator of saturated fatty acid (FA)-induced beta cell death was investigated.

METHODS

The effects of the FA palmitate on p66(Shc) expression were evaluated in human and murine islets and in rat insulin-secreting INS-1E cells. p66(Shc) expression was also measured in islets from mice fed a high-fat diet (HFD) and from human donors with different BMIs. Cell apoptosis was quantified by two independent assays. The role of p66(Shc) was investigated using pancreatic islets from p66 (Shc-/-) mice and in INS-1E cells with knockdown of p66(Shc) or overexpression of wild-type and phosphorylation-defective p66(Shc). Production of reactive oxygen species (ROS) was evaluated by the dihydroethidium oxidation method.

RESULTS

Palmitate induced a selective increase in p66(Shc) protein expression and phosphorylation on Ser(36) and augmented apoptosis in human and mouse islets and in INS-1E cells. Inhibiting the tumour suppressor protein p53 prevented both the palmitate-induced increase in p66(Shc) expression and beta cell apoptosis. Palmitate-induced apoptosis was abrogated in islets from p66 (Shc-/-) mice and following p66 (Shc) knockdown in INS-1E cells; by contrast, overexpression of p66(Shc), but not that of the phosphorylation-defective p66(Shc) mutant, enhanced palmitate-induced apoptosis. The pro-apoptotic effects of p66(Shc) were dependent upon its c-Jun N-terminal kinase-mediated phosphorylation on Ser(36) and associated with generation of ROS. p66(Shc) protein expression and function were also elevated in islets from HFD-fed mice and from obese/overweight cadaveric human donors.

CONCLUSIONS/INTERPRETATION

p53-dependent augmentation of p66(Shc) expression and function represents a key signalling response contributing to beta cell apoptosis under conditions of lipotoxicity.

Pros and cons of fatty acids in bone biology

Despite the growing interest in deciphering the causes and consequences of obesity-related disorders, the mechanisms linking fat intake to bone behaviour remain unclear. Since bone fractures are widely associated with increased morbidity and mortality, most notably in elderly and obese people, bone health has become a major social and economic issue. Consistently, public health system guidelines have encouraged low-fat diets in order to reduce associated complications. However, from a bone point of view, mechanisms linking fat intake to bone alteration remain quite controversial. Thus, after more than a decade of dedicated studies, this timely review offers a comprehensive overview of the relationships between bone and fatty acids. Using clinical evidences as a starting-point to more complex molecular elucidation, this work highlights the complexity of the system and reveals that bone alteration that cannot be solved simply by taking ω-3 pills. Fatty acid effects on bone metabolism can be both direct and indirect and require integrated investigations. Furthermore, even at the level of a single cell, one fatty acid is able to trigger several different independent pathways (receptors, metabolites…) which may all have a say in the final cellular metabolic response.

Oleic acid phase behavior from molecular dynamics simulations

Fatty acid aggregation is important for a number of diverse applications: from origins of life research to industrial applications to health and disease. Experiments have characterized the phase behavior of oleic acid mixtures, but the molecular details are complex and hard to probe with many experiments. Coarse-grained molecular dynamics computer simulations and free energy calculations are used to model oleic acid aggregation. From random dispersions, we observe the aggregation of oleic acid monomers into micelles, vesicles, and oil phases, depending on the protonation state of the oleic acid head groups. Worm-like micelles are observed when all the oleic acid molecules are deprotonated and negatively charged. Vesicles form spontaneously if significant amounts of both neutral and negative oleic acid are present. Oil phases form when all the fatty acids are protonated and neutral. This behavior qualitatively matches experimental observations of oleic acid aggregation. To explain the observed phase behavior, we use umbrella sampling free energy calculations to determine the stability of individual monomers in aggregates compared to water. We find that both neutral and negative oleic acid molecules prefer larger aggregates, but neutral monomers prefer negatively charged aggregates and negative monomers prefer neutral aggregates. Both neutral and negative monomers are most stable in a DOPC bilayer, with implications on fatty acid adsorption and cellular membrane evolution. Although the CG model qualitatively reproduces oleic acid phase behavior, we show that an updated polarizable water model is needed to more accurately predict the shift in pKa for oleic acid in model bilayers.

DHEA supplementation in ovariectomized rats reduces impaired glucose-stimulated insulin secretion induced by a high-fat diet

Dehydroepiandrosterone (DHEA) and the dehydroepiandrosterone sulfate (DHEA-S) are steroids produced mainly by the adrenal cortex. There is evidence from both human and animal models suggesting beneficial effects of these steroids for obesity, diabetes mellitus, hypertension, and osteoporosis, conditions associated with the post-menopausal period. Accordingly, we hypothesized that DHEA supplementation in ovariectomized (OVX) female rats fed a high-fat diet would maintain glucose-induced insulin secretion (GSIS) and pancreatic islet function. OVX resulted in a 30% enlargement of the pancreatic islets area compared to the control rats, which was accompanied by a 50% reduction in the phosphorylation of AKT protein in the pancreatic islets. However, a short-term high-fat diet induced insulin resistance, accompanied by impaired GSIS in isolated pancreatic islets. These effects were reversed by DHEA treatment, with improved insulin sensitivity to levels similar to the control group, and with increased serine phosphorylation of the AKT protein. These data confirm the protective effect of DHEA on the endocrine pancreas in a situation of diet-induced overweight and low estrogen concentrations, a phenotype similar to that of the post-menopausal period.

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Dehydroepiandrosterone (DHEA) is a physiological precursor of androgens and estrogens.

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Ovariectomized rats fed a high-fat diet showed insulin resistance and impaired glucose-induced insulin secretion.

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These effects were reversed by DHEA treatment, with improved insulin secretion and sensitivity.

α-linolenic acid inhibits human renal cell carcinoma cell proliferation through PPAR-γ activation and COX-2 inhibition

ω-3 fatty acids have potential anticancer effects, and consuming food rich in ω-3 fatty acids reduces the human renal cell carcinoma (RCC) risk. However, the direct effect of ω-3 fatty acids on RCC in vitro is unknown. In the present study, the effects of α-linolenic acid (ALA), an ω-3 fatty acid, were observed on cell proliferation in the RCC cell line OS-RC-2. The activity and gene expression levels of peroxisome proliferator-activated receptor-γ (PPAR-γ) and cyclooxygenase-2 (COX-2) in the OS-RC-2 cells were measured by ELISA and real-time RT-PCR, respectively, following ALA treatment. ALA (20–80 μM) dose-dependently suppressed the proliferation of the OS-RC-2 cells. PPAR-γ activity and gene expression were significantly increased by ALA at 20 and 40 μM. COX-2 activity and gene expression levels were significantly decreased by ALA from 20 μM. Use of purely the PPAR-γ agonist, rosiglitazone, decreased the proliferation of the OS-RC-2 cells, while ALA induced further suppression of cell proliferation in the presence of rosiglitazone. The COX-2 inhibitor N-(3-Pyridyl)indomethacinamide induced further suppression of cell proliferation in the presence of rosiglitazone. N-(3-Pyridyl)indomethacinamide also suppressed the proliferation of the OS-RC-2 cells. In the presence of N-(3-Pyridyl)indomethacinamide, ALA and rosiglitazone further inhibited OS-RC-2 cell proliferation. In conclusion, ALA inhibits the cell proliferation of the OS-RC-2 human RCC cell line. PPAR-γ activation and COX-2 inhibition serve as two signaling pathways for the inhibitory effects of ALA on RCC cell proliferation.

Protective Effects of Oleic Acid Against Palmitic Acid-Induced Apoptosis in Pancreatic AR42J Cells and Its Mechanisms

Palmitic acid (PAM), one of the most common saturated fatty acid (SFA) in animals and plants, has been shown to induce apoptosis in exocrine pancreatic AR42J cells. In this study, we investigated cellular mechanisms underlying protective effects of oleic acid (OLA) against the lipotoxic actions of PAM in AR42J cells. Exposure of cells to long-chain SFA induced apoptotic cell death determined by MTT cell viability assay and Hoechst staining. Co-treatment of OLA with PAM markedly protected cells against PAM-induced apoptosis. OLA significantly attenuated the PAM-induced increase in the levels of pro-apoptotic Bak protein, cleaved forms of apoptotic proteins (caspase-3, PARP). On the contrary, OLA restored the decreased levels of anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-xL, and Mcl-1) in PAM-treated cells. OLA also induced up-regulation of the mRNA expression of Dgat2 and Cpt1 genes which are involved in triacylglycerol (TAG) synthesis and mitochondrial β-oxidation, respectively. Intracellular TAG accumulation was increased by OLA supplementation in accordance with enhanced expression of Dgat2 gene. These results indicate that restoration of anti-apoptotic/pro-apoptotic protein balance from apoptosis toward cell survival is involved in the cytoprotective effects of OLA against PAM-induced apoptosis in pancreatic AR42J cells. In addition, OLA-induced increase in TAG accumulation and up-regulation of Dgat2 and Cpt1 gene expressions may be possibly associated in part with the ability of OLA to protect cells from deleterious actions of PAM.

Cadmium induces apoptosis in pancreatic β-cells through a mitochondria-dependent pathway: the role of oxidative stress-mediated c-Jun N-terminal kinase activation

Cadmium (Cd), one of well-known highly toxic environmental and industrial pollutants, causes a number of adverse health effects and diseases in humans. The growing epidemiological studies have suggested a possible link between Cd exposure and diabetes mellitus (DM). However, the toxicological effects and underlying mechanisms of Cd-induced pancreatic β-cell injury are still unknown. In this study, we found that Cd significantly decreased cell viability, and increased sub-G1 hypodiploid cells and annexin V-Cy3 binding in pancreatic β-cell-derived RIN-m5F cells. Cd also increased intracellular reactive oxygen species (ROS) generation and malondialdehyde (MDA) production and induced mitochondrial dysfunction (the loss of mitochondrial membrane potential (MMP) and the increase of cytosolic cytochrome c release), the decreased Bcl-2 expression, increased p53 expression, poly (ADP-ribose) polymerase (PARP) cleavage, and caspase cascades, which accompanied with intracellular Cd accumulation. Pretreatment with the antioxidant N-acetylcysteine (NAC) effectively reversed these Cd-induced events. Furthermore, exposure to Cd induced the phosphorylations of c-jun N-terminal kinases (JNK), extracellular signal-regulated kinases (ERK)1/2, and p38-mitogen-activated protein kinase (MAPK), which was prevented by NAC. Additionally, the specific JNK inhibitor SP600125 or JNK-specific small interference RNA (si-RNA) transfection suppressed Cd-induced β-cell apoptosis and related signals, but not ERK1/2 and p38-MAPK inhibitors (PD98059 and SB203580) did not. However, the JNK inhibitor or JNK-specific si-RNA did not suppress ROS generation in Cd-treated cells. These results indicate that Cd induces pancreatic β-cell death via an oxidative stress downstream-mediated JNK activation-triggered mitochondria-regulated apoptotic pathway.

Influence of fatty acids on mitochondrial metabolism of adipocyte progenitors and endothelial cells

CONTEXT

In obesity, the cells are exposed to excessive amounts of nutrients, especially free fatty acids (FFAs) that induce a variety of metabolic changes.

OBJECTIVE

We investigated the effect of FFAs on the mitochondrial function in different cell populations under stress conditions.

METHODS

Human adipose tissue progenitor cells (SVF) or endothelial cells (HUVECs) were incubated with 30μM of selected saturated or unsaturated FFA for 24 h, at times supplemented with 5ng/mL tumour necrosis factor alpha (TNFα) for the last 4 h. Changes in oxygen respiration rate, mitochondrial membrane potential (mitoMP) and total ATP content were monitored.

RESULTS

Saturated palmitic acid demonstrated no effect, while a selection of unsaturated FFAs ameliorated metabolism of the progenitor SVF cells. TNFα either did not affect or nullified some of the favourable FFA-induced effects.

CONCLUSIONS

The mitoMP was the most sensitive parameter reflecting positive impact of the unsaturated FFA on the adipose SVF cells' metabolism.

Oleic acid modulates metabolic substrate channeling during glucose-stimulated insulin secretion via NAD(P)H oxidase

Positive acute effects of fatty acids (FA) on glucose-stimulated insulin secretion (GSIS) and reactive oxygen species (ROS) formation have been reported. However, those studies mainly focused on palmitic acid actions, and reports on oleic acid (OA) are scarce. In this study, the effect of physiological OA levels on β-cell function and the mechanisms involved were investigated. Analyses of insulin secretion, FA and glucose oxidation, and ROS formation showed that, at high glucose concentration, OA treatment increases GSIS in parallel with increased ROS content. At high glucose, OA oxidation was increased, accompanied by a suppression of glucose oxidation. Using approaches for protein knockdown of FA receptor G protein-coupled receptor 40 (GPR40) and of p47(PHOX), a reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase component, we observed that GPR40 does not mediate OA effects on ROS formation and GSIS. However, in p47(PHOX) knockdown islets, OA-induced ROS formation and the inhibitory effect of OA on glucose metabolism was abolished. Similar results were obtained by pharmacological inhibition of protein kinase C, a known activator of NAD(P)H oxidase. Thus, ROS derived from OA metabolism via NAD(P)H oxidase are an inhibitor of glucose oxidation. Put together, these results indicate that OA acts as a modulator of glucose oxidation via ROS derived from its own metabolism in β-cells.

Alterations of NADPH oxidase activity in rat pancreatic islets induced by a high-fat diet

OBJECTIVE

The aim of this study was to evaluate the effect of a high-fat diet (HFD) on nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in rat pancreatic islets. We investigated if changes in NADPH oxidase are connected to beta cell dysfunction reported in obese animals.

METHODS

Male Wistar rats were fed a HFD or control diet for 3 months. DNA fragmentation, insulin secretion, and [U-C]glucose oxidation were examined in isolated pancreatic islets. The oxidative stress markers nitrotyrosine and 4-hydroxy-2-nonenal were assessed by immunohistochemistry. The protein content of gp91 and p47 was evaluated by Western blotting. Production of reactive oxygen species (ROS) was determined by a fluorescence assay using hydroethidine.

RESULTS

Occurrence of DNA fragmentation was reduced in pancreatic islets from HFD rats. There were no differences in oxidative stress markers between the groups. Glucose oxidation and insulin secretion were elevated due to high glucose in pancreatic islets from HFD rats. Protein concentrations of p47 and gp91 subunits were reduced and ROS production was diminished in pancreatic islets from HFD rats.

CONCLUSIONS

The diminished content of NADPH oxidase subunits and ROS concentrations may be associated with increased glucose oxidation and insulin secretion in an attempt to compensate for the peripheral insulin resistance elicited by the HFD.

Effects of human serum albumin complexed with free fatty acids on cell viability and insulin secretion in the hamster pancreatic β-cell line HIT-T15

AIMS

The effects of human serum albumin (HSA) complexed with various free fatty acids (FFAs) on ß-cells have not been studied in detail. In this study, we examined the effects of HSA and its mutants on FFA-induced cell viability changes and insulin secretion from the hamster pancreatic insulinoma cell line, HIT-TI5.

MAIN METHODS

Cells were exposed to different FFAs in the presence of HSA or its mutants and/or bovine serum albumin (BSA) for 24h. Cell viability, apoptosis, insulin secretion, and unbound FFA (FFA(u)) levels were determined.

KEY FINDINGS

In the presence of 0.1mM HSA, palmitate and stearate induced significant cell death at 0.1mM or higher, whereas myristate, palmitoleate, oleate, elaidate, linoleate, linoelaidate, and conjugated linoleate showed minimal changes on cell viability. Furthermore, oleate and linoleate were clearly cytoprotective against palmitate-induced cell death. The apoptosis inhibitors, cyclosporin A (csA) and the caspase inhibitor ZVAD-FMK, did not completely prevent FFA-induced cell death, although ZVAD-FMK blocked apoptosis with no differences in the presence of either HSA or BSA. In addition, insulin secretion from the cells was significantly reduced in the presence of HSA/oleate complexes. We also found differential effects of HSA mutants complexed with FFAs on cell viability.

SIGNIFICANCE

In summary, our results showed that saturated FFAs induced more cell death than unsaturated FFAs. Furthermore, modified HSA/FFA interactions caused by mutations of key amino acids involved in the binding of FFA to HSA resulted in changes in cell viability, suggesting a possible role of HSA polymorphism on FFA-induced changes in cellular functions.

Peroxisome-generated hydrogen peroxide as important mediator of lipotoxicity in insulin-producing cells

OBJECTIVE

Type 2 diabetes is a complex disease that is accompanied by elevated levels of nonesterified fatty acids (NEFAs), which contribute to β-cell dysfunction and β-cell loss, referred to as lipotoxicity. Experimental evidence suggests that oxidative stress is involved in lipotoxicity. In this study, we analyzed the molecular mechanisms of reactive oxygen species-mediated lipotoxicity in insulin-producing RINm5F cells and INS-1E cells as well as in primary rat islet cells.

RESEARCH DESIGN AND METHODS

The toxicity of saturated NEFAs with different chain lengths upon insulin-producing cells was determined by MTT and propidium iodide (PI) viability assays. Catalase or superoxide dismutase overexpressing cells were used to analyze the nature and the cellular compartment of reactive oxygen species formation. With the new H₂O₂-sensitive fluorescent protein HyPer H₂O₂ formation induced by exposure to palmitic acid was determined.

RESULTS

Only long-chain (>C14) saturated NEFAs were toxic to insulin-producing cells. Overexpression of catalase in the peroxisomes and in the cytosol, but not in the mitochondria, significantly reduced H₂O₂ formation and protected the cells against palmitic acid-induced toxicity. With the HyPer protein, H₂O₂ generation was directly detectable in the peroxisomes of RINm5F and INS-1E insulin-producing cells as well as in primary rat islet cells.

CONCLUSIONS

The results demonstrate that H₂O₂ formation in the peroxisomes rather than in the mitochondria are responsible for NEFA-induced toxicity. Therefore, we propose a new concept of fatty acid-induced β-cell lipotoxicity mediated via reactive oxygen species formation through peroxisomal β- oxidation.

The effects of palmitate on hepatic insulin resistance are mediated by NADPH Oxidase 3-derived reactive oxygen species through JNK and p38MAPK pathways

Elevated plasma free fatty acid (FFA) levels in obesity may play a pathogenic role in the development of insulin resistance. However, molecular mechanisms linking FFA to insulin resistance remain poorly understood. Oxidative stress acts as a link between FFA and hepatic insulin resistance. NADPH oxidase 3 (NOX3)-derived reactive oxygen species (ROS) may mediate the effect of TNF-α on hepatocytes, in particular the drop in cellular glycogen content. In the present study, we define the critical role of NOX3-derived ROS in insulin resistance in db/db mice and HepG2 cells treated with palmitate. The db/db mice displayed increased serum FFA levels, excess generation of ROS, and up-regulation of NOX3 expression, accompanied by increased lipid accumulation and impaired glycogen content in the liver. Similar results were obtained from palmitate-treated HepG2 cells. The exposure of palmitate elevated ROS production and NOX3 expression and, in turn, increased gluconeogenesis and reduced glycogen content in HepG2 cells. We found that palmitate induced hepatic insulin resistance through JNK and p38(MAPK) pathways, which are rescued by siRNA-mediated NOX3 reduction. In conclusion, our data demonstrate a critical role of NOX3-derived ROS in palmitate-induced insulin resistance in hepatocytes, indicating that NOX3 is the predominant source of palmitate-induced ROS generation and that NOX3-derived ROS may drive palmitate-induced hepatic insulin resistance through JNK and p38(MAPK) pathways.

Unsaturated fatty acids as cytoprotective agents in the pancreatic beta-cell

It is widely accepted that, in type 2 diabetes, elevated levels of free fatty acids and glucose contribute to a state of glucolipotoxicity in which beta-cell function declines and, ultimately, cell viability is compromised. This suggests that beta-cells do not readily tolerate chronic elevations in fatty acid levels. In vitro studies suggest, however, that beta-cells respond differentially to long chain fatty acids, such that saturated species are lipotoxic whereas long chain mono-unsaturated fatty acids can provide cytoprotection. This difference does not appear to be mediated by a mutual metabolic antagonism between saturated and unsaturated species (although differential alterations in neutral lipid disposition may occur in response to these fatty acids) and the mechanisms remain unclear. This review summaries the current understanding of the actions of mono-unsaturated fatty acids in beta-cells and highlights areas of controversy as well as key unresolved issues which require to be addressed.

The emerging role of cardiovascular risk factor-induced mitochondrial dysfunction in atherogenesis

An important role in atherogenesis is played by oxidative stress, which may be induced by common risk factors. Mitochondria are both sources and targets of reactive oxygen species, and there is growing evidence that mitochondrial dysfunction may be a relevant intermediate mechanism by which cardiovascular risk factors lead to the formation of vascular lesions. Mitochondrial DNA is probably the most sensitive cellular target of reactive oxygen species. Damage to mitochondrial DNA correlates with the extent of atherosclerosis. Several cardiovascular risk factors are demonstrated causes of mitochondrial damage. Oxidized low density lipoprotein and hyperglycemia may induce the production of reactive oxygen species in mitochondria of macrophages and endothelial cells. Conversely, reactive oxygen species may favor the development of type 2 diabetes mellitus, mainly through the induction of insulin resistance. Similarly - in addition to being a cause of endothelial dysfunction, reactive oxygen species and subsequent mitochondrial dysfunction - hypertension may develop in the presence of mitochondrial DNA mutations. Finally, other risk factors, such as aging, hyperhomocysteinemia and cigarette smoking, are also associated with mitochondrial damage and an increased production of free radicals. So far clinical studies have been unable to demonstrate that antioxidants have any effect on human atherogenesis. Mitochondrial targeted antioxidants might provide more significant results.

Comparative effects of DHA and EPA on cell function

Fish oil supplementation has been reported to be generally beneficial in autoimmune, inflammatory and cardiovascular disorders. Most researchers have attributed these beneficial effects to the high content of omega-3 fatty acids in fish oil (FO). The effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are not differentiated in most studies. In fact, up to 1990, purified DHA was not available for human use and there was no study regarding its effects on human immune response. In this review, the differences in the effects of these two fatty acids on cell function are discussed. Studies have shown that EPA and DHA have also different effects on leukocyte functions such as phagocytosis, chemotactic response and cytokine production. DHA and EPA modulate differently expression of genes in lymphocytes. Activation of intracellular signaling pathways involved with lymphocyte proliferation is also differently affected by these two fatty acids. In relation to insulin producing cell line RINm5F, DHA and EPA are cytotoxic at different concentrations and the proteins involved with cell death are differently modulated by these two fatty acids. Substantial improvement in the therapeutic usage of omega-3 fatty acid-rich FO will be possible with the discovery of the different mechanisms of actions of DHA and EPA.

Changes in plasma free fatty acid levels in septic patients are associated with cardiac damage and reduction in heart rate variability

Free fatty acids (FFAs) have been shown to produce alteration of heart rate variability (HRV) in healthy and diabetic individuals. Changes in HRV have been described in septic patients and in those with hyperglycemia and elevated plasma FFA levels. We studied if sepsis-induced heart damage and HRV alteration are associated with plasma FFA levels in patients. Thirty-one patients with sepsis were included. The patients were divided into two groups: survivors(n = 12) and nonsurvivors (n = 19). The following associations were investigated: (a) troponin I elevation and HRV reduction and (b) clinical evolution and HRV index, plasma troponin, and plasma FFA levels. Initial measurements of C-reactive protein and gravity Acute Physiology and Chronic Health Evaluation scores were similar in both groups. Overall, an increase in plasma troponin level was related to increased mortality risk. From the first day of study, the nonsurvivor group presented a reduced left ventricular stroke work systolic index and a reduced low frequency (LF) that is one of HRV indexes. The correlation coefficient for LF values and troponin was r(2) = 0.75 (P < 0.05). All patients presented elevated plasma FFA levels on the first day of the study (5.11 +/- 0.53 mg/mL), and this elevation was even greater in the nonsurvivor group compared with the survivors (6.88 +/- 0.13 vs. 3.85 +/- 0.48 mg/mL, respectively; P < 0.05). Cardiac damage was confirmed by measurement of plasma troponin I and histological analysis. Heart dysfunction was determined by left ventricular stroke work systolic index and HRV index in nonsurvivor patients. A relationship was found between plasma FFA levels, LFnu index, troponin levels, and histological changes. Plasma FFA levels emerged as possible cause of heart damage in sepsis.

Soybean oil treatment impairs glucose-stimulated insulin secretion and changes fatty acid composition of normal and diabetic islets

We investigated the effect of sub-chronic soybean oil (SO) treatment on the insulin secretion and fatty acid composition of islets of Langerhans obtained from Goto-Kakizaki (GK), a model of type 2 diabetes, and normal Wistar rats. We observed that soybean-treated Wistar rats present insulin resistance and defective islet insulin secretion when compared with untreated Wistar rats. The decrease in insulin secretion occurred at all concentrations of glucose and arginine tested. Furthermore we observed that soybean-treated normal islets present a significant decrease in two saturated fatty acids, myristic and heneicosanoic acids, and one monounsaturated eicosenoic acid, and the appearance of the monounsaturated erucic acid. Concerning diabetic animals, we observed that soybean-treated diabetic rats, when compared with untreated GK rats, present an increase in plasma non-fasting free fatty acids, an exacerbation of islet insulin secretion impairment in all conditions tested and a significant decrease in the monounsaturated palmitoleic acid. Altogether our results show that SO treatment results in a decrease of insulin secretion and alterations on fatty acid composition in normal and diabetic islets. Furthermore, the impairment of insulin secretion, islet erucic acid and fasting plasma insulin levels are similar in treated normal and untreated diabetic rats, suggesting that SO could have a deleterious effect on beta-cell function and insulin sensitivity.

Mechanisms involved in the cytotoxic and cytoprotective actions of saturated versus monounsaturated long-chain fatty acids in pancreatic beta-cells

Long-chain saturated and monounsaturated fatty acids differ in their propensity to induce beta-cell death in vitro with palmitate (C16:0) being cytotoxic, whereas palmitoleate (C16:1n-7) is cytoprotective. We now show that this cytoprotective capacity extends to a poorly metabolised C16:1n-7 derivative, methyl-palmitoleate (0.25 mM palmitate alone: 92 +/- 4% death after 18 h; palmitate plus 0.25 mM methyl-palmitoleate: 12 +/- 2%; P < 0.001). Palmitoleate and its methylated derivative also acted as mitogens in cultured beta-cells (5-bromo-2-deoxyuridine incorporation - control: 0.15 +/- 0.01 units; 0.25 mM palmitoleate: 0.22 +/- 0.01 units; P < 0.05). It has been proposed that alterations in neutral lipid synthesis (particularly triacylglycerol (TAG) formation) might mediate the differential responses to saturated and unsaturated fatty acids and we have examined this proposition. Palmitate and palmitoleate both promoted beta-cell phospholipid remodelling and increased TAG formation (control: 0.9 +/- 0.1 nmol TAG/10(6) cells; 0.25 mM palmitate: 1.55 +/- 0.07; 0.25 mM palmitoleate: 1.4 +/- 0.05; palmitate plus palmitoleate: 2.3 +/- 0.1). By contrast, methyl-palmitoleate failed to influence TAG levels (0.25 mM methyl-palmitoleate alone: 0.95 +/- 0.06 nmol TAG/10(6) cells; methyl-palmitoleate plus palmitate: 1.5 +/- 0.05) or its fatty acid composition in beta-cells exposed to palmitate. The results suggest that monounsaturated fatty acids can promote cell viability and mitogenesis by a mechanism that does not require their metabolism and is independent of alterations in TAG formation.

Diabetes associated cell stress and dysfunction: role of mitochondrial and non-mitochondrial ROS production and activity

It is now widely accepted, given the current weight of experimental evidence, that reactive oxygen species (ROS) contribute to cell and tissue dysfunction and damage caused by glucolipotoxicity in diabetes. The source of ROS in the insulin secreting pancreatic beta-cells and in the cells which are targets for insulin action has been considered to be the mitochondrial electron transport chain. While this source is undoubtably important, we provide additional information and evidence for NADPH oxidase-dependent generation of ROS both in pancreatic beta-cells and in insulin sensitive cells. While mitochondrial ROS generation may be important for regulation of mitochondrial uncoupling protein (UCP) activity and thus disruption of cellular energy metabolism, the NADPH oxidase associated ROS may alter parameters of signal transduction, insulin secretion, insulin action and cell proliferation or cell death. Thus NADPH oxidase may be a useful target for intervention strategies based on reversing the negative impact of glucolipotoxicity in diabetes.

Life and death decisions of the pancreatic β-cell: the role of fatty acids

Both stimulatory and detrimental effects of NEFAs (non-esterified fatty acids) on pancreatic β-cells have been recognized. Acute exposure of the pancreatic β-cell to high glucose concentrations and/or saturated NEFAs results in a substantial increase in insulin release, whereas chronic exposure results in desensitization and suppression of secretion, followed by induction of apoptosis. Some unsaturated NEFAs also promote insulin release acutely, but they are less toxic to β-cells during chronic exposure and can even exert positive protective effects. Therefore changes in the levels of NEFAs are likely to be important for the regulation of β-cell function and viability under physiological conditions. In addition, the switching between endogenous fatty acid synthesis or oxidation in the β-cell, together with alterations in neutral lipid accumulation, may have critical implications for β-cell function and integrity. Long-chain acyl-CoA (formed from either endogenously synthesized or exogenous fatty acids) controls several aspects of β-cell function, including activation of specific isoenzymes of PKC (protein kinase C), modulation of ion channels, protein acylation, ceramide formation and/or NO-mediated apoptosis, and transcription factor activity. In this review, we describe the effects of exogenous and endogenous fatty acids on β-cell metabolism and gene and protein expression, and have explored the outcomes with respect to insulin secretion and β-cell integrity.

Effect of fish oil supplementation for 2 generations on changes in macrophage function induced by Walker 256 cancer cachexia in rats

The effect of coconut fat (rich in medium saturated fatty acids) or fish oil (rich in omega-3 polyunsaturated fatty acids) supplementation for 2 generations on tumor growth, cancer cachexia, animal survival and macrophage function was investigated in Walker 256 tumor-bearing rats. Female Wistar rats were supplemented with coconut fat or fish oil prior to mating and then throughout pregnancy and gestation. Both supplementations were daily and orally given at 1 g per kg body weight as a single bolus. Same treatment was performed by the 2 following generations. At 90 days of age, male offspring (50%) from F2 generation were subcutaneously inoculated with 2 x 10(7) Walker 256 tumor cells. At 14 days after tumor implantation, rats not supplemented displayed cancer cachexia characterized by loss of body weight, hypoglycemia, hyperlacticidemia, hypertriglyceridemia, decreased food intake and depletion of glycogen stores in the liver and skeletal muscles. Supplementation with coconut fat did not affect these parameters. However, supplementation with fish oil decreased tumor growth (59%), prevented body weight loss and food intake reduction and attenuated cancer cachexia. In addition, fish oil increased animal survival up to 20 days (from 25% in rats not supplemented to 67% in rats supplemented with fish oil) and improved macrophage function characterized by increased phagocytosis capacity and production of hydrogen peroxide and nitric oxide. These results suggest that fish oil supplementation for 2 generations improves macrophage function in association to reduced tumor growth and attenuated cancer cachexia, maintaining food intake and increasing animal survival.