Fat Of Mice Research Articles

An omega-3 polyunsaturated fatty acid derivative, 18-HEPE, protects against CXCR4-associated melanoma metastasis.

Melanoma has a high propensity to metastasize and exhibits a poor response to classical therapies. Dysregulation of the chemokine receptor gene CXCR4 is associated with melanoma progression, and although n-3 polyunsaturated fatty acids (PUFAs) are known to be beneficial for melanoma prevention, the underlying mechanism of this effect is unclear. Here, we used the n-3 fatty acid desaturase (Fat-1) transgenic mouse model of endogenous n-3 PUFA synthesis to investigate the influence of elevated n-3 PUFA levels in a mouse model of metastatic melanoma. We found that relative to wild-type (WT) mice, Fat-1 mice exhibited fewer pulmonary metastatic colonies and improved inflammatory indices, including reduced serum tumor necrosis factor alpha (TNF-α) levels and pulmonary myeloperoxidase activity. Differential PUFA metabolites in serum were considered a key factor to alter cancer cell travelling to lung, and we found that n-6 PUFAs such as arachidonic acid induced CXCR4 protein expression although n-3 PUFAs such as eicosapentaenoic acid (EPA) decreased CXCR4 levels. In addition, serum levels of the bioactive EPA metabolite, 18-HEPE, were elevated in Fat-1 mice relative to WT mice, and 18-HEPE suppressed CXCR4 expression in B16-F0 cells. Moreover, relative to controls, numbers of pulmonary metastatic colonies were reduced in WT mice receiving intravenous injections either of 18-HEPE or 18-HEPE-pretreated melanoma cells. Our results indicate that 18-HEPE is a potential anticancer metabolite that mediates, at least in part, the preventive effect of n-3 PUFA on melanoma metastasis.

Applying stable carbon isotopic analysis at the natural abundance level to determine the origin of docosahexaenoic acid in the brain of the fat-1 mouse

A key factor limiting the study of the origin and metabolism of brain fatty acids is the lack of cost-efficient methods available to trace fatty acids. Here, through the application of compound-specific isotope analysis (CSIA), a novel, cost-efficient method, we successfully differentiated between brain DHA originating directly from dietary omega (n)−3 polyunsaturated fatty acids (PUFA), and brain DHA biochemically synthesized to determine the origin of brain DHA in fat-1 mice. Fat-1 mice and their wild-type littermates were either weaned onto n−6 PUFA rich, n−3 PUFA deficient diets or diets rich in both n−3 and n−6 PUFA. Isotopic analysis of fatty acid methyl esters from brain and liver tissue was conducted via gas chromatography- isotope ratio mass spectrometry. Our data demonstrates that in the presence of n−3 and n−6 PUFA, fat-1 mice obtain their brain DHA solely from n−3 PUFA sources. This study reflects the first application of CSIA to a complex multivariate model to determine the origin of brain fatty acids.

Endogenous n-3 polyunsaturated fatty acids prevent azoxymethane-induced colon tumorigenesis in mice fed a high-fat diet

Literature suggests important roles of a high-fat diet (HFD) in tumour development, but the underlying mechanisms remain poorly understood. This study assessed the protective effect of n-3 polyunsaturated fatty acids (PUFAs) on HFD-enhanced colon tumours and the underlying mechanism. WT mice were fed a normal fat diet or HFD and Fat-1 mice were fed a HFD for 22 weeks. For weeks 1–6, all mice were intraperitoneally administered AOM weekly. HFD significantly enhanced AOM-induced colon tumorigenesis in WT mice; however, tumour incidence and multiplicity were markedly lower in Fat-1 mice. HFD-triggered tumour development involved the activation of inflammatory signalling pathways, including TNF-α/NF-κB, IL-6/STAT3, and downstream NLRP3/IL-1β pathways and upregulation of β-catenin/c-myc pathway, which is associated with cancer cell proliferation. n-3 PUFAs inhibited colon tumour development and mitigated the changes to the aforementioned inflammatory pathways and oncogenic signalling. We provide experimental evidence for the role of n-3 PUFAs as potential chemopreventive agents against colon cancer.

Atopic dermatitis-like skin lesions are suppressed in fat-1 transgenic mice through the inhibition of inflammasomes

Previous clinical trials have addressed the beneficial effects of fish oil supplementation on atopic dermatitis. Recently, we reported that fat-1 mice, which can convert n-6 to n-3 polyunsaturated fatty acids (PUFAs), are protected against allergic airway inflammation because their Th2 immune responses are suppressed. Here, we examined the effects of endogenously synthesized n-3 PUFAs on atopic dermatitis, a representative Th2-dominant allergic inflammatory disease. Mouse models of atopic dermatitis-like skin lesions were prepared by epicutaneous application of 2,4-dinitrochlorobenzene (DNCB) or house dust mite (HDM) extract to the ears. DNCB-treated fat-1 mice exhibited markedly reduced epidermal thickening, lower mast cell infiltration, and lower serum IgE and histamine compared with wild-type mice. The draining lymph nodes of fat-1 mice were substantially smaller and contained significantly smaller proportions of activated CD4+ T cells and IL-4-producing Th2 cells than those of wild-type mice. Consistent with these findings, the mRNA levels of Th2 cytokines were significantly decreased in DNCB-sensitized skin lesions of fat-1 mice. Lastly, inflammasome activation, IL-1β production, and pyroptotic cell injury were suppressed in fat-1 mice. Similar results were observed in HDM-challenged fat-1 mice. This study confirms the results of previous clinical studies and suggests fish oil supplementation as a therapeutic strategy for atopic dermatitis-like skin lesions.

Amelioration of UVB-induced oxidative stress and inflammation in fat-1 transgenic mouse skin

ω-3 polyunsaturated fatty acids (PUFAs), which are abundant in fish oils, are known to scavenge lipid peroxyl radicals and potentiate host immune defence. As UVB-induced oxidative stress and inflammation have been implicated in apoptotic cell death, this study was aimed to investigate the anti-inflammatory, anti-oxidative, and anti-apoptotic capacity of fat-1 transgenic mice capable of converting ω-6 to ω-3 PUFAs. Wild-type (WT) C57BL/6 mice and fat-1 mice were maintained on the AIN-93 diet supplemented with 10% safflower oil rich in ω-6 PUFAs for 5 weeks. The ω-3/ω-6 PUFA ratio was significantly higher in the dorsal skin of fat-1 mice than that in the WT mice. Upon single exposure to UVB (5.0 kJ/m2) radiation, fat-1 mice showed inflammatory as well as oxidative tissue damage and the expression of pro-inflammatory enzymes, cyclooxygenases-2 and inducible nitric oxide synthase in the skin to a much lesser extent than the WT mice. The protection of fat-1 mice from UVB-induced skin inflammation was associated with decreased phosphorylation of STAT3. Moreover, UVB-induced apoptosis was attenuated in fat-1 mouse skin. In comparison to WT animals, higher levels of Nrf2 and its target proteins, such as heme oxygenase-1, NAD(P)H:quinone oxidoreductase-1 and thioredoxin-1, were found in the skin of fat-1 mice.

Increased brain docosahexaenoic acid has no effect on the resolution of neuroinflammation following intracerebroventricular lipopolysaccharide injection

Resolution of inflammation in the periphery was once thought to be a passive process, but new research now suggests it is an active process mediated by specialized pro-resolving lipid mediators (SPM) derived from omega-3 polyunsaturated fatty acids (n-3 PUFA). However, this has yet to be illustrated in neuroinflammation. The purpose of this study was to measure resolution of neuroinflammation and to test whether increasing brain docosahexaenoic acid (DHA) affects the resolution of neuroinflammation.C57Bl/6 mice, fat-1 mice and their wildtype littermates, fed either fish oil or safflower oil, received lipopolysaccharide (LPS) in the left lateral ventricle. Animals were then euthanized at various time points for immunohistochemistry, gene expression, and lipidomic analyses.Peak microglial activation was observed at 5 days post-surgery and the resolution index was 10 days. Of the approximately 350 genes significantly changed over the 28 days post LPS injection, 130 were uniquely changed at 3 days post injection. No changes were observed in the bioactive mediator pools. However, a few lysophospholipid species were decreased at 24hr post surgery. When brain DHA is increased, microglial cell density did not resolve faster and did not alter gene expression.In conclusion, resolution of neuroinflammation appears to be independent of SPM. Increasing brain DHA had no effect in this model.

Endogenous synthesis of n-3 polyunsaturated fatty acids in fat-1 transgenic mice ameliorates streptozocin-induced diabetic nephropathy

Although n-3 polyunsaturated fatty acids (PUFAs) exhibit biological activity in many inflammatory diseases, their renoprotective effects against diabetic nephropathy (DN) have been controversial. Here, fat-1 transgenic mice were used to investigate the effects of n-3 PUFAs on streptozocin (STZ)-induced DN. Fat-1 mice exhibited increased renal n-3 PUFAs and n-3 PUFA-derived lipid mediators, compared to wild type (WT) mice. Endogenous n-3 PUFAs protected STZ-treated fat-1 mice against hyperglycemia-induced renal dysfunction, as reflected by significant decreases in kidney/body weight ratio, urinary protein, blood urea nitrogen levels and creatinine clearance. In addition, endogenous n-3 PUFAs significantly ameliorated hyperglycemia-induced renal damage by modulating E-cadhein expression. It was also found that DN-induced NLRP3 inflammasome activation was attenuated by endogenous n-3 PUFAs in STZ-treated fat-1 mice. Our findings suggest that endogenous n-3 PUFAs ameliorate DN potentially through the: (i) formation of n-3 lipid mediators, (ii) induction of E-cadherin expression and (iii) inhibition of NLRP3 inflammasome.

Acetaminophen-induced liver injury is attenuated in transgenic fat-1 mice endogenously synthesizing long-chain n-3 fatty acids

Acetaminophen (APAP) overdose-induced hepatotoxicity is the most commonly cause of drug-induced liver failure characterized by oxidative stress, mitochondrial dysfunction, and cell damage. Therapeutic efficacy of omega-3 polyunsaturated fatty acids (n-3 PUFA) in several models of liver disease is well documented. However, the impacts of n-3 PUFA on APAP hepatotoxicity are not adequately addressed. In this study, the fat-1 transgenic mice that synthesize endogenous n-3 PUFA and wild type (WT) littermates were injected intraperitoneally with APAP at the dose of 400 mg/kg to induce liver injury, and euthanized at 0 h, 2 h, 4 h and 6 h post APAP injection for sampling. APAP overdose caused severe liver injury in WT mice as indicated by serum parameters, histopathological changes and hepatocyte apoptosis, which were remarkably ameliorated in fat-1 mice. These protective effects of n-3 PUFA were associated with regulation of the prolonged JNK activation via inhibition of apoptosis signal-regulating kinase 1 (ASK1)/mitogen-activated protein kinase kinase 4 (MKK4) pathway. Additionally, the augment of endogenous n-3 PUFA reduced nuclear factor kappa B (NF-κB) – mediated inflammation response induced by APAP treatment in the liver. These findings indicate that n-3 PUFA has potent protective effects against APAP-induced acute liver injury, suggesting that n-3 dietary supplement with n-3 PUFA may be a potential therapeutic strategy for the treatment of hepatotoxicity induced by APAP overdose.

N-3 polyunsaturated fatty acids restore Th17 and Treg balance in collagen antibody-induced arthritis.

N-3 polyunsaturated fatty acids (PUFA) have anti-inflammatory effects and were considered useful for the treatment of rheumatoid arthritis (RA). Recently, several studies suggested that n-3 PUFAs attenuated arthritis in animal model and human, however the mechanism is still unclear. Interleukin 17 (IL-17) is a pro-inflammatory cytokine mainly produced by T helper 17 (Th17) cells which cause tissue inflammation and bone erosion leading to joint destruction. In contrast, regulatory T (Treg) cells down-regulate various immune responses by suppression of naïve T cells. The imbalance between Th17 cells and Tregs cell is important for the pathogenesis of RA. Here, we investigated whether n-3 PUFAs attenuate arthritis in collagen antibody-induced arthritis (CAIA) model. We used fat-1 transgenic mice expressing the Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase that converts n-6 to n-3 fatty acids, leading to abundant n-3 fatty acids without the need of a dietary n-3 supply. Clinical arthritis score was significantly attenuated in fat-1 mice compared to wild type (WT) mice on day 7 (1.6±1.8, p = 0.012) and day 9 (1.5±1.6, p = 0.003). Ankle thickness also decreased significantly in fat-1 mice compared to WT mice (1.82±0.11, p = 0.008). The pathologic finding showed that inflammatory cell infiltration and bone destruction were reduced in fat-1 mice compared to WT. The expression levels of IL-17 and related cytokines including IL-6 and IL-23 decreased in the spleen and ankle joint tissue of fat-1 mice compared to WT mice. Furthermore, Treg cells were expanded in the spleen of fat-1 mice and Treg cell differentiation was significantly higher in fat-1 mice than in wild type (p = 0.038). These data suggest that n-3 PUFAs could attenuate arthritis through increasing the expression of FoxP3 and the differentiation of Treg, while reducing IL-17 production. Therefore, dietary supplementation of n-3 PUFAs could have a therapeutic potential for the treatment of RA.

A Weighty Matter: Can PUFAs in Pregnancy Prevent Obesity?

The prevalence of overweight and obesity has increased around the world and across all age-groups. In addition to reductions in physical activity and increases in the energy, sugar, and fat content of the diet, other contributors acting in early life are increasingly recognized, such as maternal obesity, gestational diabetes mellitus, antibiotic exposure, and maternal diet. Recently, in high-fat diet rodent models of maternal obesity, lowering the maternal ratio of n-6 to n-3 fatty acids using a novel genetic model or supplemental fish oil has been shown to prevent offspring obesity (1) and development of insulin resistance (1,2). Reported in this issue of Diabetes , Rudolph et al. (3) used an elegant model to study the effects of a low maternal n-6/n-3 polyunsaturated fatty acid (PUFA) ratio on the propensity of the offspring to develop diet-induced obesity. They studied the offspring of the fat-1 mouse, which expresses an enzyme not found in mammals that converts n-6 to n-3 PUFAs (4). Using this model instead of a nutritional intervention isolates the effects of the n-6/n-3 ratio from the potential confounding effects of diet. It also avoids the underrecognized problems associated with oxidation of PUFA-rich supplements or feed. Importantly, offspring exposed to a low maternal n-6/n-3 ratio were resistant to developing obesity and insulin resistance when challenged with a high-fat, high-sucrose “cafeteria” …

Dietary fish oil, and to a lesser extent the fat-1 transgene, increases astrocyte activation in response to intracerebroventricular amyloid-β 1–40 in mice

Objectives: Increases in astrocytes and one of their markers, glial fibrillary acidic protein (GFAP) have been reported in the brains of patients with Alzheimer’s disease (AD). N-3 polyunsaturated fatty acids (PUFA) modulate neuroinflammation in animal models; however, their effect on astrocytes is unclear.Methods: Fat-1 mice and their wildtype littermates were fed either a fish oil diet or a safflower oil diet deprived of n-3 PUFA. At 12 weeks, mice underwent intracerebroventricular infusion of amyloid-β 1-40. Astrocyte phenotype in the hippocampus was assessed at baseline and 10 days post-surgery using immunohistochemistry with various microscopy and image analysis techniques.Results: GFAP increased in all groups in response to amyloid-β, with a greater increase in fish oil-fed mice than either fat-1 or wildtype safflower oil-fed mice. Astrocytes in this group were also more hypertrophic, suggesting increased activation. Both fat-1- and fish oil-fed mice had greater increases in branch number and length in response to amyloid-β infusion than wildtype safflower animals.Conclusion: Fish oil feeding, and to a lesser extent the fat-1 transgene, enhances the astrocyte activation phenotype in response to amyloid-β 1-40. Astrocytes in mice fed fish oil were more activated in response to amyloid-β than in fat-1 mice despite similar levels of hippocampal n-3 PUFA, which suggests that other fatty acids or dietary factors contribute to this effect.

Fish oil feeding attenuates neuroinflammatory gene expression without concomitant changes in brain eicosanoids and docosanoids in a mouse model of Alzheimer’s disease

BackgroundNeuroinflammation is a recognized hallmark of Alzheimer’s disease, along with accumulation of amyloid-β plaques, neurofibrillary tangles and synaptic loss. n-3 polyunsaturated fatty acids (PUFA) and molecules derived from them, including eicosapentaenoic acid-derived eicosanoids and docosahexaenoic acid-derived docosanoids, are known to have both anti-inflammatory and pro-resolving properties, while human observational data links consumption of these fatty acids to a decreased risk of Alzheimer’s disease. Few studies have examined the neuroinflammation-modulating effects of n-3 PUFA feeding in an Alzheimer’s disease-related model, and none have investigated whether these effects are mediated by changes in brain eicosanoids and docosanoids. Here, we use both a fat-1 transgenic mouse and a fish oil feeding model to study the impact of increasing tissue n-3 PUFA on neuroinflammation and the production of pro-inflammatory and pro-resolving lipid mediators. MethodsFat-1 mice, transgenic animals that can convert n-6 to n-3 PUFA, and their wildtype littermates were fed diets containing either fish oil (high n-3 PUFA) or safflower oil (negligible n-3 PUFA) from weaning to 12 weeks. Animals then underwent intracerebroventricular infusion of either amyloid-β 1-40 or a control peptide. Hippocampi were collected from non-surgery and surgery animals 10 days after infusion. Microarray was used to measure enrichment of inflammation-associated gene categories and expression of genes involved in the synthesis of lipid mediators. Results were validated by real-time PCR in a separate cohort of animals. Lipid mediators were measured via liquid chromatography tandem mass spectrometry. ResultsFat-1 and wildtype mice fed fish oil had higher total hippocampal DHA than wildtype mice fed the safflower oil diet. The safflower-fed mice, but not the fat-1 or fish oil-fed mice, had significantly increased expression in gene ontology categories associated with inflammation in response to amyloid-β infusion. These effects were independent of changes in the expression of genes involved in the synthesis of eicosanoids or docosanoids in any group. Gene expression was replicated upon validation in the wildtype safflower and fish oil-fed, but not the fat-1 mice. Protectin, maresin and D and E series resolvins were not detected in any sample. There were no major differences in levels of other eicosanoids or docosanoids between any of the groups in response to amyloid-β infusion. ConclusionsFish oil feeding decreases neuroinflammatory gene expression in response to amyloid-β. Neither amyloid-β infusion or increasing brain DHA affects the brain concentrations of specialized pro-resolving mediators in this model, or the concentrations of most other eicosanoids and docosanoids.

Phospholipid species distribution patterns in the mouse vascular organ of the lamina terminalis during systemic inflammation

Omega-3 fatty acids (3-FAs) modulate inflammation and brain-controlled febrile responses during inflammation. Here, we aimed to characterize the distribution and relative concentrations of several lipids (e.g. phosphatidylcholine, PC) including 3-FA-carrying lipids in a brain structure important for immune-to- brain communication, namely the vascular organ of the lamina terminalis (OVLT), during systemic lipopolysaccharide (LPS)-induced inflammation. For this purpose, wild type and fat-1 transgenic mice which produce large quantities of omega 3-FA endogenously, were stimulated with LPS (i.p., 2.5 mg/kg) or saline. Animals were sacrificed (5 h, 24 h), brains and blood samples were collected and analyzed by immunohistochemistry, high-resolution atmospheric-pressure scanning microprobe matrix assisted laser desorption/ionization ion source combined with an orbital trapping mass spectrometer and bioassays, respectively. Telemetric recordings revealed moderate hypothermia in LPS-treated fat-1 mice but fever in wildtype counterparts. Moreover, depending on genotypes and treatment, several distinct distribution patterns were observed for putative inflammation-involved phospholipids [e.g. PC(38:6), LysoPC(16:0)/(18:0), PE (P-36:4)] ranging from equal distributions, accumulation or absence within the OVLT compared to adjacent brain tissue. A localized increase of LysoPCs was indicative of enhanced LPS-induced turnover of fatty acid metabolism in the OVLT in fat-1 mice compared to wild type controls. Overall, screening of lipid distribution patterns revealed distinct inflammation-induced changes in the OVLT highlighting its prominent role for lipid metabolism and brain inflammation. New candidates for brain inflammation and immune-to-brain communication have been detected.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy.

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

High Endogenous Accumulation of ω-3 Polyunsaturated Fatty Acids Protect against Ischemia-Reperfusion Renal Injury through AMPK-Mediated Autophagy in Fat-1 Mice

Regulated autophagy is involved in the repair of renal ischemia-reperfusion injury (IRI). Fat-1 transgenic mice produce ω3-Polyunsaturated fatty acids (ω3-PUFAs) from ω6-Polyunsaturated fatty acids (ω6-PUFAs) without a dietary ω3-PUFAs supplement, leading to a high accumulation of omega-3 in various tissues. ω3-PUFAs show protective effects against various renal injuries and it has recently been reported that ω3-PUFAs regulate autophagy. We assessed whether ω3-PUFAs attenuated IR-induced acute kidney injury (AKI) and evaluated its associated mechanisms. C57Bl/6 background fat-1 mice and wild-type mice (wt) were divided into four groups: wt sham (n = 10), fat-1 sham (n = 10), wt IRI (reperfusion 35 min after clamping both the renal artery and vein; n = 15), and fat-1 IRI (n = 15). Kidneys and blood were harvested 24 h after IRI and renal histological and molecular data were collected. The kidneys of fat-1 mice showed better renal cell survival, renal function, and pathological damage than those of wt mice after IRI. In addition, fat-1 mice showed less oxidative stress and autophagy impairment; greater amounts of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, Beclin-1, and Atg7; lower amounts of p62; and, higher levels of renal cathepsin D and ATP6E than wt kidneys. They also showed more adenosine monophosphate-activated protein kinase (AMPK) activation, which resulted in the inhibition of phosphorylation of the mammalian target of rapamycin (mTOR). Collectively, ω3-PUFAs in fat-1 mice contributed to AMPK mediated autophagy activation, leading to a renoprotective response.

Modulation of the endogenous omega-3 fatty acid and oxylipin profile in vivo-A comparison of the fat-1 transgenic mouse with C57BL/6 wildtype mice on an omega-3 fatty acid enriched diet.

Dietary intervention and genetic fat-1 mice are two models for the investigation of effects associated with omega-3 polyunsaturated fatty acids (n3-PUFA). In order to assess their power to modulate the fatty acid and oxylipin pattern, we thoroughly compared fat-1 and wild-type C57BL/6 mice on a sunflower oil diet with wild-type mice on the same diet enriched with 1% EPA and 1% DHA for 0, 7, 14, 30 and 45 days. Feeding led after 14–30 days to a high steady state of n3-PUFA in all tissues at the expense of n6-PUFAs. Levels of n3-PUFA achieved by feeding were higher compared to fat-1 mice, particularly for EPA (max. 1.7% in whole blood of fat-1 vs. 7.8% following feeding). Changes in PUFAs were reflected in most oxylipins in plasma, brain and colon: Compared to wild-type mice on a standard diet, arachidonic acid metabolites were overall decreased while EPA and DHA oxylipins increased with feeding more than in fat-1 mice. In plasma of n3-PUFA fed animals, EPA and DHA metabolites from the lipoxygenase and cytochrome P450 pathways dominated over ARA derived counterparts.Fat-1 mice show n3-PUFA level which can be reached by dietary interventions, supporting the applicability of this model in n3-PUFA research. However, for specific questions, e.g. the role of EPA derived mediators or concentration dependent effects of (individual) PUFA, feeding studies are necessary.

Abstract 2110: Anti-invasive and antimetastatic actions of omega-3 polyunsaturated fatty acids in glioblastoma cells

Abstract Glioblastoma (GBM) is the most aggressive and deadliest brain malignancy in adults. Despite of surgical techniques, radiotherapy and chemotherapy, GBM has remained an invariably lethal tumor with a median survival less than 15 months. Although the anticancer mechanisms of omega-3 polyunsaturated fatty acids (ω3-PUFAs) have been reported in several cancers, it is still unclear in brain cancer. Here, our data show the anti-invasive and anti-metastatic effects of ω3-PUFAs in GBM. Invasiveness using transwell chamber was inhibited by docosahexaenoic acid (DHA) treatment in D54MG and GL261 cells. In zymography, MMP-2 activity was suppressed by DHA in a dose dependent manner. MMP-2 promoter activity was also decreased. DHA inhibited both p-STAT3 and β-catenin levels that contribute to invasion by stimulating pro-invasion factors such as MMP-2. Additionally, fat-1 (ω3-desaturease) stable D54MG cell was established and the effect of the high level of ω3-PUFAs was investigated endogenously. The invasiveness were significantly inhibited in the fat-1 stable cells compared to control cell. Moreover, the metastasis in vivo was significantly reduced when GL261 mouse glioma cells were injected through tail vein into the fat-1 transgenic mice. In immunohistochemistry, intensity of p-STAT-3 and β-catenin were significantly weak in metastatic lung tumor from Fat-1 mice compared to wild type mice. These results indicate that anti-invasive and anti-metastatic actions of ω3-PUFA may be correlated with inhibition of MMP-2 through decrease of STAT3 and β-catenin in GBM cells. Thus, these findings provide important preclinical evidence and molecular insight for utilization of ω-3 PUFAs for the chemoprevention and treatment of human GBM. [This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (2007-0054932, NRF-2015R1D1A1A01056887) and by the framework of international cooperation program managed by National Research Foundation of Korea (2015K2A2A6002008)]. Citation Format: Soyeon Kim, Soyeon Shin, Soyeon Jeong, Seung-Hyeon Han, Yoon-Seon Yoo, Prashanta Silwal, Young-Joo Jeon, Jun-Young Heo, Gi-Ryang Kweon, Seung-Kiel Park, Jong-Il Park, Kyu Lim. Anti-invasive and antimetastatic actions of omega-3 polyunsaturated fatty acids in glioblastoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2110. doi:10.1158/1538-7445.AM2017-2110

OP-30 - Protective Effects of fat-1 Gene against UVB-induced Oxidative Stress and Inflammation in Mouse Skin

Omega-6 (ω-6) and omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) are known to have opposite effects on the inflammation-associated carcinogenesis. Generally, ω-6 PUFAs promote inflammation and tumor development, whereas ω-3 PUFAs possess anti-inflammatory as well as antioxidative activity. In the present study, we investigated the protective capability of ω-3 PUFAs endogenously produced in fat-1 transgenic mice. The ω-3/ω-6 PUFA ratio was significantly higher in the dorsal skin of fat-1 mice than that in the wild-type (WT) C57BL/6 mice. In comparison to WT animals, elevated levels of heme oxygenase-1 and NAD(P)H:quinone oxidoreductase-1, were found in the skin of fat-1 mice, which was attributable to the enhanced activation of nuclear factor erythroid-related factor-2 (Nrf2). Upon single exposure to UVB (5.0 kJ/m2) radiation, fat­-1 mice showed a markedly reduced degree of skin inflammation and expression of pro-inflammatory enzymes, cyclooxygenases-2 and inducible nitric oxide synthase, compared with the WT animals. The protection of fat-1 mice from UVB-induced phototoxicity was associated with decreased phosphorylation of STAT3. In conclusion, our results show that fat-1 gene confers a protective effect against UVB-induced inflammatory and oxidative skin damages through augmented endogenous ω-3 PUFA production.

Constitutive ω-3 fatty acid production in fat-1 transgenic mice and docosahexaenoic acid administration to wild type mice protect against 2,4,6-trinitrobenzene sulfonic acid-induced colitis

Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) are known to have strong anti-inflammatory effects. In the present study, we investigated the protective effects of ω-3 PUFAs on experimentally induced murine colitis. Intrarectal administration of 2.5% 2,4,6-trinitrobenzene sulfonic acid (TNBS) caused inflammation in the colon of wild type mice, but this was less severe in fat-1 transgenic mice that constitutively produce ω-3 PUFAs from ω-6 PUFAs. The intraperitoneal administration of docosahexaenoic acid (DHA), a representative ω-3 PUFA, was also protective against TNBS-induced murine colitis. In addition, endogenously formed and exogenously introduced ω-3 PUFAs attenuated the production of malondialdehyde and 4-hydroxynonenal in the colon of TNBS-treated mice. The effective protection against inflammatory and oxidative colonic tissue damages in fat-1 and DHA-treated mice was associated with suppression of NF-κB activation and cyclooxygenase-2 expression and with elevated activation of Nrf2 and upregulation of its target gene, heme oxygenase-1. Taken together, these results provide mechanistic basis of protective action of ω-3 fatty PUFAs against experimental colitis.

Quantitative Profiling of Hydroxy Lipid Metabolites in Mouse Organs Reveals Distinct Lipidomic Profiles and Modifications Due to Elevated n-3 Fatty Acid Levels

Polyunsaturated fatty acids (PUFA) are precursors of bioactive metabolites and mediators. In this study, the profile of hydroxyeicosatetraenoic (HETE), hydroxyeicosapentaenoic (HEPE) and hydroxydocosahexaenoic (HDHA) acids derived from arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in colon, liver, lung, spleen, muscle, heart and kidney tissue of healthy wildtype mice were characterized, and compared to profiles in organs from transgenic fat-1 mice engineered to express the Caenorhabditis elegans fat-1 gene encoding an n-3 desaturase and thereby with endogenously elevated n-3 PUFA levels. PUFAs were measured using gas chromatography. The lipid metabolites were assayed using LC-MS/MS. AA and DHA were the prominent PUFAs in wildtype and fat-1 mice. EPA levels were low in both groups even though there was a significant increase in fat-1 organs with an up to 12-fold increase in fat-1 spleen and kidney. DHA levels increased by approximately 1.5-fold in fat-1 as compared to wildtype mice. While HETEs remained the same or decreased moderately and HDHAs increased 1- to 3-fold, HEPE formation in fat-1 tissues increased from 8- (muscle) to 44-fold (spleen). These findings indicate distinct profiles of monohydroxy lipid metabolites in different organs and strong utilization of EPA for HEPE formation, by which moderate EPA supplementation might trigger formation of biologically active EPA-derived resolvins.