Association of MTHFR (C677T, A1298C) and MTRR A66G polymorphisms with fatty acids profile and risk of neural tube defects.

OBJECTIVE: This study aims to determine if 5,10-methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and methionine synthase reductase (MTRR A66G) gene polymorphisms were associated with fatty acid (FA) levels in mothers of fetuses with neural tube defects (NTDs) and whether these associations were modified by environmental factors. METHODS: Plasma FA composition was assessed using capillary gas chromatography. Concentrations of studied FA were compared between 42 mothers of NTDs fetuses and 30 controls as a function of each polymorphism by the Kruskal-Wallis nonparametric test. RESULTS: In MTHFR gene C677T polymorphism, cases with (CT + TT) genotype had lower monounsaturated FAs (MUFA) and omega-3 polyunsaturated FA (n-3 PUFA) levels, but higher omega-6 polyunsaturated FAs (n-6 PUFA) and omega-6 polyunsaturated FAs: omega-3 polyunsaturated FAs (n-6:n-3) ratio levels. In MTRR gene A66G polymorphism, cases with (AG + GG) genotype had lower MUFA levels, but higher PUFA and n-6 PUFA levels. Controls with (AG + GG) genotype had lower n-6 PUFA levels. In MTHFR gene C677T polymorphism, cases with smoking spouses and (CT + TT) genotype had lower MUFA and n-3 PUFA levels, but higher PUFA, n-6 PUFA, and n-6:n-3 ratio levels. Cases with (CT + TT) genotype and who used sauna during pregnancy had lower n-3 PUFA levels. In MTRR gene A66G polymorphism, cases with (AG + GG) genotype and who used sauna during pregnancy had higher PUFA and n-6 PUFA levels. CONCLUSIONS: Further research is required to clarify the association of FA metabolism and (MTHFR, MTRR) polymorphisms with NTDs.

Lipidomic and transcriptomic analysis of western diet-induced nonalcoholic steatohepatitis (NASH) in female Ldlr -/- mice.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, particularly in obese and type 2 diabetic individuals. NAFLD ranges in severity from benign steatosis to nonalcoholic steatohepatitis (NASH); and NASH can progress to cirrhosis, primary hepatocellular carcinoma (HCC) and liver failure. As such, NAFLD has emerged as a major public health concern. Herein, we used a lipidomic and transcriptomic approach to identify lipid markers associated with western diet (WD) induced NASH in female mice. METHODS: Female mice (low-density lipoprotein receptor null (Ldlr -/-) were fed a reference or WD diet for 38 and 46 weeks. Transcriptomic and lipidomic approaches, coupled with statistical analyses, were used to identify associations between major NASH markers and transcriptomic & lipidomic markers. RESULTS: The WD induced all major hallmarks of NASH in female Ldlr -/- mice, including steatosis (SFA, MUFA, MUFA-containing di- and triacylglycerols), inflammation (TNFα), oxidative stress (Ncf2), and fibrosis (Col1A). The WD also increased transcripts associated with membrane remodeling (LpCat), apoptosis & autophagy (Casp1, CtsS), hedgehog (Taz) & notch signaling (Hey1), epithelial-mesenchymal transition (S1004A) and cancer (Gpc3). WD feeding, however, suppressed the expression of the hedgehog inhibitory protein (Hhip), and enzymes involved in triglyceride catabolism (Tgh/Ces3, Ces1g), as well as the hepatic abundance of C18-22 PUFA-containing phosphoglycerolipids (GpCho, GpEtn, GpSer, GpIns). WD feeding also increased hepatic cyclooxygenase (Cox1 & 2) expression and pro-inflammatory ω6 PUFA-derived oxylipins (PGE2), as well as lipid markers of oxidative stress (8-iso-PGF2α). The WD suppressed the hepatic abundance of reparative oxylipins (19, 20-DiHDPA) as well as the expression of enzymes involved in fatty epoxide metabolism (Cyp2C, Ephx). CONCLUSION: WD-induced NASH in female Ldlr -/- mice was characterized by a massive increase in hepatic neutral and membrane lipids containing SFA and MUFA and a loss of C18-22 PUFA-containing membrane lipids. Moreover, the WD increased hepatic pro-inflammatory oxylipins and suppressed the hepatic abundance of reparative oxylipins. Such global changes in the type and abundance of hepatic lipids likely contributes to tissue remodeling and NASH severity.

Transcriptome Profiles of Human Visceral Adipocytes in Obesity and Colorectal Cancer Unravel the Effects of Body Mass Index and Polyunsaturated Fatty Acids on Genes and Biological Processes Related to Tumorigenesis.

Obesity, a low-grade inflammatory condition, represents a major risk factor for the development of several pathologies including colorectal cancer (CRC). Although the adipose tissue inflammatory state is now recognized as a key player in obesity-associated morbidities, the underlying biological processes are complex and not yet precisely defined. To this end, we analyzed transcriptome profiles of human visceral adipocytes from lean and obese subjects affected or not by CRC by RNA sequencing (n = 6 subjects/category), and validated selected modulated genes by real-time qPCR. We report that obesity and CRC, conditions characterized by the common denominator of inflammation, promote changes in the transcriptional program of adipocytes mostly involving pathways and biological processes linked to extracellular matrix remodeling, and metabolism of pyruvate, lipids and glucose. Interestingly, although the transcriptome of adipocytes shows several alterations that are common to both disorders, some modifications are unique under obesity (e.g., pathways associated with inflammation) and CRC (e.g., TGFß signaling and extracellular matrix remodeling) and are influenced by the body mass index (e.g., processes related to cell adhesion, angiogenesis, as well as metabolism). Indeed, cancer-induced transcriptional program is deeply affected by obesity, with adipocytes from obese individuals exhibiting a more complex response to the tumor. We also report that in vitro exposure of adipocytes to ω3 and ω6 polyunsaturated fatty acids (PUFA) endowed with either anti- or pro-inflammatory properties, respectively, modulates the expression of genes involved in processes potentially relevant to carcinogenesis, as assessed by real-time qPCR. All together our results suggest that genes involved in pyruvate, glucose and lipid metabolism, fibrosis and inflammation are central in the transcriptional reprogramming of adipocytes occurring in obese and CRC-affected individuals, as well as in their response to PUFA exposure. Moreover, our results indicate that the transcriptional program of adipocytes is strongly influenced by the BMI status in CRC subjects. The dysregulation of these interrelated processes relevant for adipocyte functions may contribute to create more favorable conditions to tumor establishment or favor tumor progression, thus linking obesity and colorectal cancer.

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.

Omega-3 fatty acids and leukocyte-endothelium adhesion: Novel anti-atherosclerotic actions.

Endothelial cells (ECs) play a role in the optimal function of blood vessels. When endothelial function becomes dysregulated, the risk of developing atherosclerosis increases. Specifically, upregulation of adhesion molecule expression on ECs promotes the movement of leukocytes, particularly monocytes, into the vessel wall. Here, monocytes differentiate into macrophages and may become foam cells, contributing to the initiation and progression of an atherosclerotic plaque. The ability of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) to influence the expression of adhesion molecules by ECs and to modulate leukocyte-endothelial adhesion has been studied in cell culture using various types of ECs, in animal feeding studies and in human trials; the latter have tended to evaluate soluble forms of adhesion molecules that circulate in the bloodstream. These studies indicate that n-3 PUFAs (both eicosapentaenoic acid and docosahexaenoic acid) can decrease the expression of key adhesion molecules, such as vascular cell adhesion molecule 1, by ECs and that this results in decreased adhesive interactions between leukocytes and ECs. These findings suggest that n-3 PUFAs may lower leukocyte infiltration into the vascular wall, which could contribute to reduced atherosclerosis and lowered risk of cardiovascular disease.

Associations among FADS1 rs174547, eicosapentaenoic acid/arachidonic acid ratio, and arterial stiffness in overweight subjects.

We aimed to evaluate the longitudinal interaction effects between the minor allele of FADS1 rs174547 and overweight on n-3 and n-6 long-chain polyunsaturated fatty acid (PUFA) levels and pulse wave velocity (PWV). Plasma PUFA levels were measured via GC-MS, and arterial stiffness was determined as brachial-ankle PWV (ba-PWV) at baseline and after a mean follow-up of 3 years. The FADS1 rs174547 T > C genotype was analyzed. At 3-years of follow-up, after adjustment for age, sex, smoking and drinking, there were interaction effects between the FADS1 rs174547 T > C genotype and baseline BMI on the changes (from baseline) in plasma arachidonic acid (AA) levels, in the eicosapentaenoic acid (EPA)/AA ratio, and in ba-PWV (p for interaction = 0.036, 0.022, and 0.001, respectively). There were smaller increases in AA levels from baseline among normal-weight C allele carriers (n = 112) and overweight TT subjects (n = 47) than among normal-weight TT subjects (n = 91). Overweight C allele carriers (n = 37) showed greater reductions in the plasma EPA/AA ratio and greater increases in ba-PWV than the 3 other populations studied. The minor allele of the FADS1 rs174547 polymorphism is associated with age-related decreases in the EPA/AA ratio and increases in ba-PWV among overweight subjects.

N-Docosahexaenoylethanolamine: A neurotrophic and neuroprotective metabolite of docosahexaenoic acid.

N-Docosahexaenoylethanolamine (synaptamide) is an endocannabinoid-like metabolite endogenously synthesized from docosahexaenoic acid (DHA, 22:6n-3), the major omega-3 polyunsaturated fatty acid present in the brain. Although its biosynthetic mechanism has yet to be established, there is a closely linked relationship between the levels of synaptamide and its precursor DHA in the brain. Synaptamide at nanomolar concentrations promotes neurogenesis, neurite outgrowth and synaptogenesis in developing neurons. Synaptamide also attenuates the lipopolysaccharide-induced neuroinflammatory response and reduces the deleterious effects of ethanol on neurogenic differentiation of neural stem cells (NSCs). These actions are mediated by a specific target receptor of synaptamide GPR110 (ADGRF1), a G-protein coupled receptor that is highly expressed in NSCs and the brain during development. Synaptamide binding to GPR110 induces cAMP production and phosphorylation of protein kinase A (PKA) and the cAMP response element binding protein (CREB). This signaling pathway leads to the expression of neurogenic and synaptogenic genes and suppresses the expression of proinflammatory genes. The GPR110-dependent cellular effects of synaptamide are recapitulated in animal models, suggesting that synaptamide-derived mechanisms may have translational implications. The synaptamide bioactivity transmitted by newly deorphanized GPR110 provides a novel target for neurodevelopmental and neuroprotective control as well as new insight into mechanisms for DHA's beneficial effects on the central nervous system.

Lipid droplets induced by secreted phospholipase A2 and unsaturated fatty acids protect breast cancer cells from nutrient and lipotoxic stress.

Cancer cells driven by the Ras oncogene scavenge unsaturated fatty acids (FAs) from their environment to counter nutrient stress. The human group X secreted phospholipase A2 (hGX sPLA2) releases FAs from membrane phospholipids, stimulates lipid droplet (LD) biogenesis in Ras-driven triple-negative breast cancer (TNBC) cells and enables their survival during starvation. Here we examined the role of LDs, induced by hGX sPLA2 and unsaturated FAs, in protection of TNBC cells against nutrient stress. We found that hGX sPLA2 releases a mixture of unsaturated FAs, including ω-3 and ω-6 polyunsaturated FAs (PUFAs), from TNBC cells. Starvation-induced breakdown of LDs induced by low micromolar concentrations of unsaturated FAs, including PUFAs, was associated with protection from cell death. Interestingly, adipose triglyceride lipase (ATGL) contributed to LD breakdown during starvation, but it was not required for the pro-survival effects of hGX sPLA2 and unsaturated FAs. High micromolar concentrations of PUFAs, but not OA, induced oxidative stress-dependent cell death in TNBC cells. Inhibition of triacylglycerol (TAG) synthesis suppressed LD biogenesis and potentiated PUFA-induced cell damage. On the contrary, stimulation of LD biogenesis by hGX sPLA2 and suppression of LD breakdown by ATGL depletion reduced PUFA-induced oxidative stress and cell death. Finally, lipidomic analyses revealed that sequestration of PUFAs in LDs by sPLA2-induced TAG remodelling and retention of PUFAs in LDs by inhibition of ATGL-mediated TAG lipolysis protect from PUFA lipotoxicity. LDs are thus antioxidant and pro-survival organelles that guard TNBC cells against nutrient and lipotoxic stress and emerge as attractive targets for novel therapeutic interventions.

Endogenous ω-3 Fatty Acid Production by fat-1 Transgene and Topically Applied Docosahexaenoic Acid Protect against UVB-induced Mouse Skin Carcinogenesis.

The present study was intended to explore the effects of endogenously produced ω-3 polyunsaturated fatty acids (PUFAs) on ultraviolet B (UVB)-induced skin inflammation and photocarcinogenesis using hairless fat-1 transgenic mice harboring ω-3 desaturase gene capable of converting ω-6 to ω-3 PUFAs. Upon exposure to UVB irradiation, fat-1 transgenic mice exhibited a significantly reduced epidermal hyperplasia, oxidative skin damage, and photocarcinogenesis as compared to wild type mice. The transcription factor, Nrf2 is a master regulator of anti-inflammatory and antioxidant gene expression. While the protein expression of Nrf2 was markedly enhanced, the level of its mRNA transcript was barely changed in the fat-1 transgenic mouse skin. Topical application of docosahexaenoic acid (DHA), a representative ω-3 PUFA, in wild type hairless mice induced expression of the Nrf2 target protein, heme oxygenase-1 in the skin and protected against UVB-induced oxidative stress, inflammation and papillomagenesis. Furthermore, transient overexpression of fat-1 gene in mouse epidermal JB6 cells resulted in the enhanced accumulation of Nrf2 protein. Likewise, DHA treated to JB6 cells inhibited Nrf2 ubiquitination and stabilized it. Taken together, our results indicate that functional fat-1 and topically applied DHA potentiate cellular defense against UVB-induced skin inflammation and photocarcinogenesis through elevated activation of Nrf2 and upregulation of cytoprotective gene expression.

Microbial and genetically engineered oils as replacements for fish oil in aquaculture feeds.

As the global population grows more of our fish and seafood are being farmed. Fish are the main dietary source of the omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, but these cannot be produced in sufficient quantities as are now required for human health. Farmed fish have traditionally been fed a diet consisting of fishmeal and fish oil, rich in n-3 LC-PUFA. However, the increase in global aquaculture production has resulted in these finite and limited marine ingredients being replaced with sustainable alternatives of terrestrial origin that are devoid of n-3 LC-PUFA. Consequently, the nutritional value of the final product has been partially compromised with EPA and DHA levels both falling. Recent calls from the salmon industry for new sources of n-3 LC-PUFA have received significant commercial interest. Thus, this review explores the technologies being applied to produce de novo n-3 LC-PUFA sources, namely microalgae and genetically engineered oilseed crops, and how they may be used in aquafeeds to ensure that farmed fish remain a healthy component of the human diet.

Dual Roles of Group IID Phospholipase A2 in Inflammation and Cancer.

Phospholipase A2 enzymes have long been implicated in the promotion of inflammation by mobilizing pro-inflammatory lipid mediators, yet recent evidence suggests that they also contribute to anti-inflammatory or pro-resolving programs. Group IID-secreted phospholipase A2 (sPLA2-IID) is abundantly expressed in dendritic cells in lymphoid tissues and resolves the Th1 immune response by controlling the steady-state levels of anti-inflammatory lipids such as docosahexaenoic acid and its metabolites. Here, we show that psoriasis and contact dermatitis were exacerbated in Pla2g2d-null mice, whereas they were ameliorated in Pla2g2d-overexpressing transgenic mice, relative to littermate wild-type mice. These phenotypes were associated with concomitant alterations in the tissue levels of ω3 polyunsaturated fatty acid (PUFA) metabolites, which had the capacity to reduce the expression of pro-inflammatory and Th1/Th17-type cytokines in dendritic cells or lymph node cells. In the context of cancer, however, Pla2g2d deficiency resulted in marked attenuation of skin carcinogenesis, likely because of the augmented anti-tumor immunity. Altogether, these results underscore a general role of sPLA2-IID as an immunosuppressive sPLA2 that allows the microenvironmental lipid balance toward an anti-inflammatory state, exerting beneficial or detrimental impact depending upon distinct pathophysiological contexts in inflammation and cancer.

Altered hepatic gene expression in nonalcoholic fatty liver disease is associated with lower hepatic n-3 and n-6 polyunsaturated fatty acids.

UNLABELLED: In nonalcoholic fatty liver disease, hepatic gene expression and fatty acid (FA) composition have been reported independently, but a comprehensive gene expression profiling in relation to FA composition is lacking. The aim was to assess this relationship. In a cross-sectional study, hepatic gene expression (Illumina Microarray) was first compared among 20 patients with simple steatosis (SS), 19 with nonalcoholic steatohepatitis (NASH), and 24 healthy controls. The FA composition in hepatic total lipids was compared between SS and NASH, and associations between gene expression and FAs were examined. Gene expression differed mainly between healthy controls and patients (SS and NASH), including genes related to unsaturated FA metabolism. Twenty-two genes were differentially expressed between NASH and SS; most of them correlated with disease severity and related more to cancer progression than to lipid metabolism. Biologically active long-chain polyunsaturated FAs (PUFAs; eicosapentaenoic acid + docosahexaenoic acid, arachidonic acid) in hepatic total lipids were lower in NASH than in SS. This may be related to overexpression of FADS1, FADS2, and PNPLA3. The degree and direction of correlations between PUFAs and gene expression were different among SS and NASH, which may suggest that low PUFA content in NASH modulates gene expression in a different way compared with SS or, alternatively, that gene expression influences PUFA content differently depending on disease severity (SS versus NASH). CONCLUSION: Well-defined subjects with either healthy liver, SS, or NASH showed distinct hepatic gene expression profiles including genes involved in unsaturated FA metabolism. In patients with NASH, hepatic PUFAs were lower and associations with gene expression were different compared to SS.

Metabolic engineering plant seeds with fish oil-like levels of DHA.

BACKGROUND: Omega-3 long-chain (≥C(20)) polyunsaturated fatty acids (ω3 LC-PUFA) have critical roles in human health and development with studies indicating that deficiencies in these fatty acids can increase the risk or severity of cardiovascular and inflammatory diseases in particular. These fatty acids are predominantly sourced from fish and algal oils, but it is widely recognised that there is an urgent need for an alternative and sustainable source of EPA and DHA. Since the earliest demonstrations of ω3 LC-PUFA engineering there has been good progress in engineering the C(20) EPA with seed fatty acid levels similar to that observed in bulk fish oil (∼18%), although undesirable ω6 PUFA levels have also remained high. METHODOLOGY/PRINCIPAL FINDINGS: The transgenic seed production of the particularly important C(22) DHA has been problematic with many attempts resulting in the accumulation of EPA/DPA, but only a few percent of DHA. This study describes the production of up to 15% of the C(22) fatty acid DHA in Arabidopsis thaliana seed oil with a high ω3/ω6 ratio. This was achieved using a transgenic pathway to increase the C(18) ALA which was then converted to DHA by a microalgal Δ6-desaturase pathway. CONCLUSIONS/SIGNIFICANCE: The amount of DHA described in this study exceeds the 12% level at which DHA is generally found in bulk fish oil. This is a breakthrough in the development of sustainable alternative sources of DHA as this technology should be applicable in oilseed crops. One hectare of a Brassica napus crop containing 12% DHA in seed oil would produce as much DHA as approximately 10,000 fish.

Fish oil enhances intestinal integrity and inhibits TLR4 and NOD2 signaling pathways in weaned pigs after LPS challenge.

Long-chain (n-3) PUFA exert beneficial effects on inflammatory bowel diseases in animal models and clinical trials. In addition, pattern recognition receptors such as toll-like receptors (TLR) and nucleotide-binding oligomerization domain proteins (NOD) play a critical role in intestinal inflammation. We hypothesized that fish oil could alleviate Escherichia coli LPS-induced intestinal injury via modulation of TLR4 and NOD signaling pathways. Twenty-four weaned piglets were used in a 2 × 2 factorial design and the main factors included a dietary treatment (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). After feeding fish oil or corn oil diets for 21 d, pigs were injected with LPS or saline. At 4 h postinjection, blood samples were collected and pigs were killed. EPA, DHA, and total (n-3) PUFA were enriched in intestinal mucosa through fish supplementation. Fish oil improved intestinal morphology, indicated by greater villus height and villus height:crypt depth ratio, and intestinal barrier function, indicated by decreased plasma diamine oxidase (DAO) activity and increased mucosal DAO activity as well as enhanced protein expression of intestinal tight junction proteins including occludin and claudin-1. Moreover, fish oil decreased intestinal TNFα and PGE(2) concentrations and caspase-3 and heat shock protein 70 protein expression. Finally, fish oil downregulated the mRNA expression of intestinal TLR4 and its downstream signals myeloid differentiation factor 88, IL-1 receptor-associated kinase 1, TNFα receptor-associated factor 6, and NOD2, and its adaptor molecule, receptor-interacting serine/threonine-protein kinase 2. Fish oil decreased the protein expression of intestinal NFκB p65. These results indicate that fish oil supplementation is associated with inhibition of TLR4 and NOD2 signaling pathways and concomitant improvement of intestinal integrity under an inflammatory condition.

Interactions between dietary n-3 fatty acids and genetic variants and risk of disease.

Nutritional genomics has undergone rapid development and the concept is now very popular with the general public. Therefore, there is increasing demand for knowledge on adapting dietary composition to the genome. Our aim has been to undertake a systematic review so as to find out the level of evidence existing on whether the effects of n-3 fatty acids on health can be modulated by genetic variation. A systematic literature search was conducted on studies that jointly analyse the effect of one or more genetic variants in candidate genes and n-3 fatty acids. Both observational and experimental studies were included. Results are classified in accordance with whether the study was undertaken on intermediate phenotypes (plasma lipid concentrations, glucose, inflammation markers, anthropometric measurements) or disease phenotypes (cancer, cardiovascular diseases, metabolic syndrome, etc) and whether it was experimental or observational. A wide diversity of genetic variants and little consistency in the publication of replication studies was found. Greater consistency was observed in studies that involved the FADS1 and FADS2 locus in the determination of n-3 fatty acid concentrations in biological samples. Most of the studies were designed to measure gene-diet interactions and not diet-gene interactions. Despite the fact that multiple studies have shown statistically significant interactions between n-3 fatty acids and certain genetic variants on intermediate and disease phenotypes, the individual level of evidence is very low and recommendations cannot be made on increasing or reducing the intake of n-3 fatty acids based on each individual's genotype.

Endogenous n-3 polyunsaturated fatty acids delay progression of pancreatic ductal adenocarcinoma in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice.

Preclinical studies suggest that diets rich in omega-3 polyunsaturated fatty acids (n-3 PUFAs) may be beneficial for prevention of pancreatic cancer. Nutritional intervention studies are often complex, and there is no clear evidence, without potential confounding factors, on whether conversion of n-6 PUFAs to n-3 PUFAs in pancreatic tissues would provide protection. Experiments were designed using n-3 fatty acid desaturase (Fat-1) transgenic mice, which can convert n-6 PUFA to n-3 FAs endogenously, to determine the impact of n-3 PUFAs on pancreatic intraepithelial neoplasms (PanINs) and their progression to pancreatic ductal adenocarcinoma (PDAC). Six-week-old female p48(Cre/+)-LSL-Kras(G12D/+) and compound Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice were fed (AIN-76A) diets containing 10% safflower oil for 35 weeks. Pancreata were evaluated histopathologically for PanINs and PDAC. Results showed a dramatic reduction in incidence of PDAC (84%; P < .02) in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice compared to p48(Cre/+)-LSL-Kras(G12D/+) mice. Importantly, significant reductions of pancreatic ducts with carcinoma (90%; P < .0001) and PanIN 3 (~50%; P < .001) lesions were observed in the compound transgenic mice. The levels of n-3 PUFA were much higher (>85%; P < .05-0.01) in pancreas of compound transgenic mice than in those of p48(Cre/+)-LSL-Kras(G12D/+) mice. Molecular analysis of the pancreas showed a significant down-regulation of proliferating cell nuclear antigen, cyclooxygenase-2, 5-lipoxygenase (5-LOX), 5-LOX-activating protein, Bcl-2, and cyclin D1 expression levels in Fat-1-p48(Cre/+)-LSL-Kras(G12D/+) mice compared to p48(Cre/+)-LSL-Kras(G12D/+) mice. These data highlight the promise of dietary n-3 FAs for chemoprevention of pancreatic cancer in high-risk individuals.

Efficient production of omega-3 fatty acid desaturase (sFat-1)-transgenic pigs by somatic cell nuclear transfer.

Omega-3(omega-3) fatty acid desaturase transgenic pigs may improve carcass fatty acid composition. The use of transgenic pigs is also an excellent large animal model for studying the role of omega-3 fatty acids in the prevention and treatment of coronary heart disease and cancer. Transgenic pigs carrying synthesized fatty acid desaturase-1 gene (sFat-1) from Caenorhabditis briggsae by somatic cell nuclear transfer (SCNT) were produced for the first time in China. Porcine fetal fibroblast cells were transfected with a sFat-1 expression cassette by the liposome-mediated method. Transgenic embryos were reconstructed by nuclear transfer of positive cells into enucleated in vitro matured oocytes. A total of 1889 reconstructed embryos were transferred into 10 naturally cycling gilts. Nine early pregnancies were established, 7 of which went to term. Twenty-one piglets were born. The cloning efficiency was 1.1% (born piglets/transferred embryos). The integration of the sFat-1 gene was confirmed in 15 live cloned piglets by PCR and Southern blot except for 2 piglets. Expression of the sFat-1 gene in 12 of 13 piglets was detected with RT-PCR. The data demonstrates that an efficient system for sFat-1 transgenic cloned pigs was developed, which led to the successful production of piglets expressing the sFat-1 gene.

Effects of omega-3 and omega-6 fatty acids on IGF-I receptor signalling in colorectal cancer cells.

The insulin-like growth factor (IGF) system plays a critical role in normal growth and development as well as in malignant states. Most of the biological activities of the IGFs are mediated by the IGF-IR, which is over-expressed in most tumours and cancer cell lines. Fatty acids have critical roles in both systemic physiological processes (e.g. metabolism) and cellular events (e.g. proliferation, apoptosis, signal transduction, and gene expression). Alpha-linolenic acid (ALA) and linoleic acid (LA) are essential fatty acids of the omega-3 and omega-6 families, respectively. The aim of this study was to investigate the potential interactions between fatty acids and the IGF signal transduction pathways, and to evaluate the impact of this interplay on colon cancer cells survival and proliferation. Results of Western blot analyses revealed that ALA and LA enhanced the ligand-induced IGF-IR phosphorylation and, in addition, increased receptor phosphorylation in an IGF-I independent manner. Furthermore, fatty acid treatment led to phosphorylation of downstream signalling molecules, including Akt and Erk. In addition, FACS analysis and apoptosis measurements indicated that ALA and LA have a potential mitogenic effect on HCT116 cells, as reflected by the number of cells in S phase and by a reduction of PARP cleavage, implying a reduction in apoptotic activity. In summary, our results provide evidence that omega-3 and omega-6 fatty acids modulate IGF-I action in colon cancer cells.

Carbamylcholine and ouabain effects on Ca2+ handling and insulin release in islets from rats depleted in long-chain polyunsaturated omega 3 fatty acids.

A number of metabolic, ionic and secretory variables were recently found to be affected in pancreatic islets obtained from second generation rats depleted in long-chain polyunsaturated omega 3 fatty acids (omega 3 rats). The present study further documents three sets of anomalies in such islets. First, after 90 min exposure to D-glucose (8.3 mM), the release of insulin from perifused islets, prelabelled with 45Ca, is lower in omega 3 rats than in control animals, despite comparable 45Ca fractional outflow rate. Second, over 15 min exposure to carbamylcholine (0.1 mM), in the presence of D: -glucose, the cytosolic concentration of Ca2+ is increased to a greater relative extent in dispersed islet cells from omega 3 rats, as compared to control animals. This coincides with a greater relative increase in insulin output from perifused islets during the second phase of the secretory response to the cholinergic agent. Last, the increase provoked by ouabain (1.0 mM) in cytosolic Ca2+ concentration, 45Ca fractional outflow rate and insulin release are all delayed in the omega 3 rats. Taking into account the decreased activity of Na+, K+-ATPase in the islets of omega 3 rats, these findings are interpreted as reflecting an impaired priming of insulin-producing cells when first exposed for 105 min to a physiological postprandial concentration of D-glucose.