Inhibition of the HER2 pathway by n-3 polyunsaturated fatty acids prevents breast cancer in fat-1 transgenic mice

The transplantation of the gut microbiome of fat-1 mice protects against colonic mucus layer disruption and endoplasmic reticulum stress induced by high fat diet

High-fat diets alter gut barrier integrity, leading to endotoxemia by impacting epithelial functions and inducing endoplasmic reticulum (ER) stress in intestinal secretory goblet cells. Indeed, ER stress, which is an important contributor to many chronic diseases such as obesity and obesity-related disorders, leads to altered synthesis and secretion of mucins that form the protective mucus barrier. In the present study, we investigated the relative contribution of omega-3 polyunsaturated fatty acid (PUFAs)-modified microbiota to alleviating alterations in intestinal mucus layer thickness and preserving gut barrier integrity. Male fat-1 transgenic mice (exhibiting endogenous omega-3 PUFAs tissue enrichment) and wild-type (WT) littermates were fed either an obesogenic high-fat diet (HFD) or a control diet. Unlike WT mice, HFD-fed fat-1 mice were protected against mucus layer alterations as well as an ER stress-mediated decrease in mucin expression. Moreover, cecal microbiota transferred from fat-1 to WT mice prevented changes in the colonic mucus layer mainly through colonic ER stress downregulation. These findings highlight a novel feature of the preventive effects of omega-3 fatty acids against intestinal permeability in obesity-related conditions.

Decorin suppresses tumor lymphangiogenesis: A mechanism to curtail cancer progression

The complex interplay between malignant cells and the cellular and molecular components of the tumor stroma is a key aspect of cancer growth and development. These tumor-host interactions are often affected by soluble bioactive molecules such as proteoglycans. Decorin, an archetypical small leucine-rich proteoglycan primarily expressed by stromal cells, affects cancer growth in its soluble form by interacting with several receptor tyrosine kinases (RTK). Overall, decorin leads to a context-dependent and protracted cessation of oncogenic RTK activity by attenuating their ability to drive a pro-survival program and to sustain a pro-angiogenic network. Through an unbiased transcriptomic analysis using deep RNAseq, we discovered that decorin downregulated a cluster of tumor-associated genes involved in lymphatic vessel development when systemically delivered to mice harboring breast carcinoma allografts. We found that Lyve1 and Podoplanin, two established markers of lymphatic vessels, were markedly suppressed at both the mRNA and protein levels and this suppression correlated with a significant reduction in tumor lymphatic vessels. We further discovered that soluble decorin, but not its homologous proteoglycan biglycan, inhibited lymphatic vessel sprouting in an ex vivo 3D model of lymphangiogenesis. Mechanistically, we found that decorin interacted with VEGFR3, the main lymphatic RTK, and its activity was required for the decorin-mediated block of lymphangiogenesis. Finally, we discovered that Lyve1 was in part degraded via decorin-evoked autophagy in a nutrient- and energy-independent manner. These findings implicate decorin as a new biological factor with anti-lymphangiogenic activity and provide a potential therapeutic agent for curtailing breast cancer growth and metastasis.

Sexual Dimorphism of the Mouse Plasma Metabolome Is Associated with Phenotypes of 30 Gene Knockout Lines

Although metabolic alterations are observed in many monogenic and complex genetic disorders, the impact of most mammalian genes on cellular metabolism remains unknown. Understanding the effect of mouse gene dysfunction on metabolism can inform the functions of their human orthologues. We investigated the effect of loss-of-function mutations in 30 unique gene knockout (KO) lines on plasma metabolites, including genes coding for structural proteins (11 of 30), metabolic pathway enzymes (12 of 30) and protein kinases (7 of 30). Steroids, bile acids, oxylipins, primary metabolites, biogenic amines and complex lipids were analyzed with dedicated mass spectrometry platforms, yielding 827 identified metabolites in male and female KO mice and wildtype (WT) controls. Twenty-two percent of 23,698 KO versus WT comparison tests showed significant genotype effects on plasma metabolites. Fifty-six percent of identified metabolites were significantly different between the sexes in WT mice. Many of these metabolites were also found to have sexually dimorphic changes in KO lines. We used plasma metabolites to complement phenotype information exemplified for Dhfr, Idh1, Mfap4, Nek2, Npc2, Phyh and Sra1. The association of plasma metabolites with IMPC phenotypes showed dramatic sexual dimorphism in wildtype mice. We demonstrate how to link metabolomics to genotypes and (disease) phenotypes. Sex must be considered as critical factor in the biological interpretation of gene functions.

Conditional expression of endorepellin in the tumor vasculature attenuates breast cancer growth, angiogenesis and hyaluronan deposition

The tumor stroma of most solid malignancies is characterized by a pathological accumulation of pro-angiogenic and pro-tumorigenic hyaluronan driving tumorigenesis and metastatic potential. Of all three hyaluronan synthase isoforms, HAS2 is the primary enzyme that promotes the build-up of tumorigenic HA in breast cancer. Previously, we discovered that endorepellin, the angiostatic C-terminal fragment of perlecan, evokes a catabolic mechanism targeting endothelial HAS2 and hyaluronan via autophagic induction. To explore the translational implications of endorepellin in breast cancer, we created a double transgenic, inducible Tie2CreERT2;endorepellin(ER)Ki mouse line that expresses recombinant endorepellin specifically from the endothelium. We investigated the therapeutic effects of recombinant endorepellin overexpression in an orthotopic, syngeneic breast cancer allograft mouse model. First, adenoviral delivery of Cre evoking intratumor expression of endorepellin in ERKi mice suppressed breast cancer growth, peritumor hyaluronan and angiogenesis. Moreover, tamoxifen-induced expression of recombinant endorepellin specifically from the endothelium in Tie2CreERT2;ERKi mice markedly suppressed breast cancer allograft growth, hyaluronan deposition in the tumor proper and perivascular tissues, and tumor angiogenesis. These results provide insight into the tumor suppressing activity of endorepellin at the molecular level and implicate endorepellin as a promising cancer protein therapy that targets hyaluronan in the tumor microenvironment.

High Endogenously Synthesized N-3 Polyunsaturated Fatty Acids in Fat-1 Mice Attenuate High-Fat Diet-Induced Insulin Resistance by Inhibiting NLRP3 Inflammasome Activation via Akt/GSK-3β/TXNIP Pathway

High-fat (HF) diets and low-grade chronic inflammation contribute to the development of insulin resistance and type 2 diabetes (T2D), whereas n-3 polyunsaturated fatty acids (PUFAs), due to their anti-inflammatory effects, protect against insulin resistance. Interleukin (IL)-1β is implicated in insulin resistance, yet how n-3 PUFAs modulate IL-1β secretion and attenuate HF diet-induced insulin resistance remains elusive. In this study, a HF diet activated NLRP3 inflammasome via inducing reactive oxygen species (ROS) generation and promoted IL-1β production primarily from adipose tissue preadipocytes, but not from adipocytes and induced insulin resistance in wild type (WT) mice. Interestingly, endogenous synthesized n-3 polyunsaturated fatty acids (PUFAs) reversed this process in HF diet-fed fat-1 transgenic mice although the HF diet induced higher weight gain in fat-1 mice, compared with the control diet. Mechanistically, palmitic acid (PA), the main saturated fatty acid in an HF diet inactivated AMPK and led to decreased GSK-3β phosphorylation, at least partially through reducing Akt activity, which ultimately blocked the Nrf2/Trx1 antioxidant pathway and induced TXNIP cytoplasm translocation and NLRP3 inflammasome activation, whereas docosahexaenoic acid (DHA), the most abundant n-3 PUFA in fat-1 adipose tissue, reversed this process via inducing Akt activation. Our GSK-3β shRNA knockdown study further revealed that GSK-3β played a pivot role between the upstream AMPK/Akt pathway and downstream Nrf2/Trx1/TXNIP pathway. Given that NLRP3 inflammasome is implicated in the development of most inflammatory diseases, our results suggest the potential of n-3 PUFAs in the prevention or adjuvant treatment of NLRP3 inflammasome-driven diseases.

Contribution of n-3 Long-Chain Polyunsaturated Fatty Acids to the Prevention of Breast Cancer Risk Factors

Nowadays, diet and breast cancer are studied at different levels, particularly in tumor prevention and progression. Thus, the molecular mechanisms leading to better knowledge are deciphered with a higher precision. Among the molecules implicated in a preventive and anti-progressive way, n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs) are good candidates. These molecules, like docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, are generally found in marine material, such as fat fishes or microalgae. EPA and DHA act as anti-proliferative, anti-invasive, and anti-angiogenic molecules in breast cancer cell lines, as well as in in vivo studies. A better characterization of the cellular and molecular pathways involving the action of these fatty acids is essential to have a realistic image of the therapeutic avenues envisaged behind their use. This need is reinforced by the increase in the number of clinical trials involving more and more n-3 LC-PUFAs, and this, in various pathologies ranging from obesity to a multitude of cancers. The objective of this review is, therefore, to highlight the new elements showing the preventive and beneficial effects of n-3 LC-PUFAs against the development and progression of breast cancer.

Single nucleotide polymorphism of fatty acid desaturase gene and breast cancer risk in estrogen receptor subtype

BACKGROUND

Breast cancer (BC) is the most common cancer of women and the second most common cancer overall globally. Data suggest that the plasma concentration of omega fatty acids (n-3 and n-6) and the impact of the genetic variant are associated with diet-related inflammatory disease, BC. This study was aimed to find an association between genetic variant rs174537 of fatty acid desaturase gene 1(FADS 1) and breast cancer estrogen receptor subtype.

METHODOLOGY

Hundred and two blood samples from women were quantified for fatty acids by gas chromatography. SNP rs 174537(G > T) showed maximum variability and the strongest genetic determinant in the Genome-wide association study were genotyped using Sanger sequencing.

RESULTS

The highest tertile of ALA showed a significantly reduced risk of BC compared to the lowest tertile (OR = 0.2, 95 %CL = 0.1-1.14, P = 0.03). Median values of ALA were higher in GT/TT genotype in ER +ve molecular subtype (P = 0.03) and DPA was higher in GG genotype of ER-ve molecular subtype (P = 0.037). When both the groups were put together the highest tertile of GG tertile showed significantly reduced risk of BC compared with the other lowest tertiles of GG and GT/TT genotypes (OR, 95% CL = 0.45(0.2-0.9).

CONCLUSION

The high levels of arachidonic acid and low levels of n-3 fatty acids result in a pro-inflammatory milieu and that these pro-inflammatory effects might contribute to BC. We conclude that the individuals with genetically determined lower activity of FADS1(minor allele T) will derive greater advantage from n-3 FAs than those with higher FADS1 activity (G allele) and reduce the BC risk.

Increased lipogenesis is critical for self-renewal and growth of breast cancer stem cells: Impact of omega-3 fatty acids

Aberrant lipid metabolism has recently been recognized as a new hallmark of malignancy, but the characteristics of fatty acid metabolism in breast cancer stem cells (BCSC) and potential interventions targeting this pathway remain to be addressed. Here, by using the in vitro BCSC models, mammosphere‐derived MCF‐7 cells and HMLE‐Twist‐ER cells, we found that the cells with stem cell‐like properties exhibited a very distinct profile of fatty acid metabolism compared with that of their parental cancer cells, characterized by increased lipogenesis, especially the activity of stearoyl‐CoA desaturase 1 (SCD1) responsible for the production of monounsaturated fatty acids, and augmented synthesis and utilization of the omega‐6 arachidonic acid (AA). Suppression of SCD1 activity by either enzyme inhibitors or small interfering RNA (siRNA) knockdown strikingly limited self‐renewal and growth of the BCSC, suggesting a key role for SCD1 in BCSC proliferation. Furthermore, elevated levels of SCD1 and other lipogenic enzymes were observed in human breast cancer tissues relative to the noncancer tissues from the same patients and correlated with the pathological grades. Interestingly, treatment of BCSC with omega‐3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, effectively downregulated the expression of the lipogenic enzymes and markedly suppressed BCSC self‐renewal and growth. Dietary supplementation of nude mice bearing BCSC‐derived tumors with omega‐3 fatty acids also significantly reduced their tumor load. These findings have demonstrated that increased lipogenesis is critical for self‐renewal and growth of BCSC, and that omega‐3 fatty acids are effective in targeting this pathway to exert their anticancer effect.

Targeting ferroptosis in breast cancer

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

EO771, is it a well-characterized cell line for mouse mammary cancer model? Limit and uncertainty

Among mouse mammary tumor models, syngeneic cell lines present an advantage for the study of immune response. However, few of these models are well characterized. The tumor line EO771 is derived from spontaneous breast cancer of C57BL/6 mice. These cells are widely used but are referenced under different names: EO771, EO 771, and E0771. The characteristics of the EO771 cells are well described but some data are contradictory. This cell line presents the great interest of developing an immunocompetent neoplastic model using an orthotopic implantation reflecting the mammary tumors encountered in breast cancer patients. This review presents the phenotype characteristics of EO771 and its sensitivity to nutrients and different therapies such as radiotherapy, chemotherapy, hormone therapy, and immunotherapy.

Effects of Different Dietary Vegetable Lipid Sources on Health Status in Nile Tilapia (Oreochromis niloticus): Haematological Indices, Immune Response Parameters and Plasma Proteome

This study aimed to investigate the effects of DLs, including palm oil (PO; an SFAs), linseed oil (LO; n-3 PUFAs) and soybean oil (SBO; n-6 PUFAs) on the health status of Nile tilapia (Oreochromis niloticus) during adulthood. Three experimental diets incorporating PO, LO or SBO were fed to adult Nile tilapia for a period of 90 days, and haematological and innate immune parameters were evaluated. Proteome analysis was also conducted to evaluate the effects of DLs on plasma proteins. The tested DLs had no significant effects on red blood cell (RBC) count, haematocrit, haemoglobin, and total immunoglobulin and lysozyme activity. Dietary LO led to increased alternative complement 50 activity (ACH50), and proteome analysis revealed that PO and SBO enhanced A2ML, suggesting that different DLs promote immune system via different processes. Dietary LO or SBO increased the expression of several proteins involved in coagulation activity such as KNG1, HRG and FGG. Increased HPX in fish fed with PO suggests that SFAs are utilised in heme lipid-oxidation. Overall, DLs with distinct fatty acids (FAs) affect several parameters corresponding to health status in Nile tilapia, and dietary LO and SBO seemed to strengthen health in this species.

CRISPR/Cas9-mediated specific integration of fat-1 at the goat MSTN locus

Recent advances in understanding the CRISPR/Cas9 system have provided a precise and versatile approach for genome editing in various species. However, no study has reported simultaneous knockout of endogenous genes and site-specific knockin of exogenous genes in large animal models. Using the CRISPR/Cas9 system, this study specifically inserted the fat-1 gene into the goat MSTN locus, thereby achieving simultaneous fat-1 insertion and MSTN mutation. We introduced the Cas9, MSTN knockout small guide RNA and fat-1 knockin vectors into goat fetal fibroblasts by electroporation, and obtained a total of 156 positive clonal cell lines. PCR and sequencing were performed for identification. Of the 156 clonal strains, 40 (25.6%) had simultaneous MSTN knockout and fat-1 insertion at the MSTN locus without drug selection, and 55 (35.25%) and 101 (67.3%) had MSTN mutations and fat-1 insertions, respectively. We generated a site-specific knockin Arbas cashmere goat model using a combination of CRISPR/Cas9 and somatic cell nuclear transfer for the first time. For biosafety, we mainly focused on unmarked and non-resistant gene screening, and point-specific gene editing. The results showed that simultaneous editing of the two genes (simultaneous knockout and knockin) was achieved in large animals, demonstrating that the CRISPR/Cas9 system has the potential to become an important and applicable gene engineering tool in safe animal breeding.

The Transplantation of ω3 PUFA-Altered Gut Microbiota of fat-1 Mice to Wild-Type Littermates Prevents Obesity and Associated Metabolic Disorders

Altering the gut microbiome may be beneficial to the host and recently arose as a promising strategy to manage obesity. Here, we investigated the relative contribution of ω3 polyunsaturated fatty acid (PUFA)-mediated alterations in the microbiota to metabolic parameter changes in mice. Four groups were compared: male fat-1 transgenic mice (with constitutive production of ω3 PUFAs) and male wild-type (WT) littermates fed an obesogenic (high fat/high sucrose [HFHS]) or a control diet. Unlike WT mice, HFHS-fed fat-1 mice were protected against obesity, glucose intolerance, and hepatic steatosis. Unlike WT mice, fat-1 mice maintained a normal barrier function, resulting in a significantly lower metabolic endotoxemia. The fat-1 mice displayed greater phylogenic diversity in the cecum, and fecal microbiota transplantation from fat-1 to WT mice was able to reverse weight gain and to normalize glucose tolerance and intestinal permeability. We concluded that the ω3 PUFA-mediated alteration of gut microbiota contributed to the prevention of metabolic syndrome in fat-1 mice. It occurred independently of changes in the PUFA content of host tissues and may represent a promising strategy to prevent metabolic disease and preserve a lean phenotype.

The ω-3 polyunsaturated fatty acids prevented colitis-associated carcinogenesis through blocking dissociation of β-catenin complex, inhibiting COX-2 through repressing NF-κB, and inducing 15-prostaglandin dehydrogenase

Numerous studies have demonstrated that diets containing an increased ratio of ω-6 : ω-3 polyunsaturated fatty acids (PUFAs) are a risk factor for colon cancer and might affect tumorigenesis. Therefore, dietary ω-3 PUFA administration may be a preventive strategy against colon cancer. Until now, the exact molecular mechanisms and required dietary doses of ω-3 PUFAs for cancer prevention were unknown. In this study, we explored the anti-tumorigenic mechanisms of ω-3 PUFAs against a colitis-associated cancer (CAC) model. Through in vitro cell models involving docosahexaenoic acid (DHA) administration, down-regulation of survivin and Bcl-2, and up-regulation of Bax, accompanied by blockage of β-catenin complex dissociation, the main mechanisms responsible for DHA-induced apoptosis in HCT116 cells were determined. Results included significant reduction in azoxymethane-initiated, dextran sodium sulfate-promoted CACs, as well as significant preservation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and significant inhibition of Cyclooxyganase-2 (COX-2) and Prostaglandin E₂(P < 0.01). Additional mechanisms and significant induction of apoptosis in both tumor and non-tumor tissues were also noted in fat-1 transgenic (TG) mice. The lipid profiles of colon tissues measured in all specimens revealed that intake greater than 3 g ω-3 PUFA/60 kg of body weight showed tissue levels similar to those seen in fat-1 TG mice, preventing cancer. Our study concluded that COX-2 inhibition, 15-PGDH preservation, apoptosis induction, and blockage of β-catenin complex dissociation contributed to the anti-tumorigenesis effect of ω-3 PUFAs, and an intake higher than 3g ω-3 PUFAs/60 kg of body weight can assist in CAC prevention.

Implications of dietary ω-3 and ω-6 polyunsaturated fatty acids in breast cancer

Breast cancer represents one of the most common forms of cancer in women worldwide, with an increase in the number of newly diagnosed patients in the last decade. The role of fatty acids, particularly of a diet rich in ω-3 and ω-6 polyunsaturated fatty acids (PUFAs), in breast cancer development is not fully understood and remains controversial due to their complex mechanism of action. However, a large number of animal models and cell culture studies have demonstrated that high levels of ω-3 PUFAs have an inhibitory role in the development and progression of breast cancer, compared to ω-6 PUFAs. The present review focused on recent studies regarding the correlation between dietary PUFAs and breast cancer development, and aimed to emphasize the main molecular mechanisms involved in the modification of cell membrane structure and function, modulation of signal transduction pathways, gene expression regulation, and antiangiogenic and antimetastatic effects. Furthermore, the anticancer role of ω-3 PUFAs through the modulation of microRNA expression levels was also reviewed.

Modulation of Ras/ERK and Phosphoinositide Signaling by Long-Chain n-3 PUFA in Breast Cancer and Their Potential Complementary Role in Combination with Targeted Drugs

A potential complementary role of the dietary long-chain n-3 polyunsaturated fatty acids (LCn-3 PUFA) in combination with innovative mono-targeted therapies has recently been proposed. These compounds are thought to act pleiotropically to prevent the development and progression of a variety of cancers, including breast cancer. We hereinafter critically analyze the reports investigating the ability of LCn-3 PUFA to modulate the Ras/ERK and the phosphoinositide survival signaling pathways often aberrantly activated in breast cancer and representing the main targets of innovative therapies. The in vitro or in vivo animal and human interventional studies published up to January 2017 investigating the effects of LCn-3 PUFA on these pathways in normal and cancerous breast cells or tissues were identified through a systematic search of literature in the PubMed database. We found that, in most cases, both the in vitro and in vivo studies demonstrated the ability of LCn-3 PUFA to inhibit the activation of these pro-survival pathways. Altogether, the analyzed results strongly suggest a potential role of LCn-3 PUFA as complementary agents in combination with mono-targeted therapies. Moreover, the results indicate the need for further in vitro and human interventional studies designed to unequivocally prove the potential adjuvant role of these fatty acids.

Human glandular organoid formation in murine engineering chambers after collagenase digestion and flow cytometry isolation of normal human breast tissue single cells

Women with high mammographic density (MD) are at increased risk of breast cancer (BC) after adjustment for age and body mass index. We have developed a murine biochamber model in which both high MD (HMD) and low MD (LMD) tissue can be propagated. Here, we tested whether cells isolated by collagenase digestion and fluorescence-activated cell sorting (FACS) from normal breast can be reconstituted in our biochamber model, which would allow cell-specific manipulations to be tested. Fresh breast tissue was collected from women (n = 7) undergoing prophylactic mastectomy. The tissue underwent collagenase digestion overnight and, in some cases, additional FACS enrichment to obtain mature epithelial, luminal progenitor, mammary stem, and stromal cells. Cells were then transferred bilaterally into biochambers in SCID mice (n = 5-7) and incubated for 6 weeks, before harvesting for histological analyses, and immunohistochemical staining for cytokeratins (CK), vimentin, Ki-67, murine macrophages, and Cleaved Caspase-3. Biochambers inoculated with single cells after collagenase digestion or with flow cytometry contained glandular structures of human origin (human vimentin-positive), which expressed CK-14 and pan-CK, and were proliferating (Ki-67-positive). Glandular structures from the digested tissues were smaller than those in chambers seeded with finely chopped intact mammary tissue. Mouse macrophage infiltration was higher in the chambers arising from digested tissues. Pooled single cells and FACS fractionated cells were viable in the murine biochambers and formed proliferating glandular organoids of human origin. This is among the first report to demonstrate the success of formed human glandular organoids from isolated primary mammary cells in the murine biochamber model.

Activation of PPARγ2 by PPARγ1 through a functional PPRE in transdifferentiation of myoblasts to adipocytes induced by EPA

PPARγ and Wnt signaling are central positive and negative regulators of adipogenesis, respectively. Here we identified that, eicosapentaenoic acid (EPA) could effectively induce the transdifferentiation of myoblasts into adipocytes through modulation of both PPARγ expression and Wnt signaling. During the early stage of transdifferentiation, EPA activates PPARδ and PPARγ1, which in turn targets β-catenin to degradation and down-regulates Wnt/β-catenin signaling, such that the myogenic fate of myoblasts could be switched to adipogenesis. In addition, EPA up-regulates the expression of PPARγ1 by activating RXRα, then PPARγ1 binds to the functional peroxisome proliferator responsive element (PPRE) in the promoter of adipocyte-specific PPARγ2 to continuously activate the expression of PPARγ2 throughout the transdifferentiation process. Our data indicated that EPA acts as a dual-function stimulator of adipogenesis that both inhibits Wnt signaling and induces PPARγ2 expression to facilitate the transdifferentiation program, and the transcriptional activation of PPARγ2 by PPARγ1 is not only the key factor for the transdifferentiation of myoblasts to adipocytes, but also the crucial evidence for successful transdifferentiation. The present findings provided insight for the first time as to how EPA induces the transdifferentiation of myoblasts to adipocytes, but also provide new clues for strategies to prevent and treat some metabolic diseases.

Inhibition of colon cancer growth by docosahexaenoic acid involves autocrine production of TNFα

The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) has anti-inflammatory and anti-cancer properties. Among pro-inflammatory mediators, tumor necrosis factor α (TNFα) plays a paradoxical role in cancer biology with induction of cancer cell death or survival depending on the cellular context. The objective of the study was to evaluate the role of TNFα in DHA-mediated tumor growth inhibition and colon cancer cell death. The treatment of human colorectal cancer cells, HCT-116 and HCT-8 cells, with DHA triggered apoptosis in autocrine TNFα-dependent manner. We demonstrated that DHA-induced increased content of TNFα mRNA occurred through a post-transcriptional regulation via the down-regulation of microRNA-21 (miR-21) expression. Treatment with DHA led to nuclear accumulation of Foxo3a that bounds to the miR-21 promoter triggering its transcriptional repression. Moreover, inhibition of RIP1 kinase and AMP-activated protein kinase α reduced Foxo3a nuclear-cytoplasmic shuttling and subsequent increase of TNFα expression through a decrease of miR-21 expression in DHA-treated colon cancer cells. Finally, we were able to show in HCT-116 xenograft tumor-bearing nude mice that a DHA-enriched diet induced a decrease of human miR-21 expression and an increase of human TNFα mRNA expression limiting tumor growth in a cancer cell-derived TNFα dependent manner. Altogether, the present work highlights a novel mechanism for anti-cancer action of DHA involving colon cancer cell death mediated through autocrine action of TNFα.

Endogenous conversion of ω-6 to ω-3 polyunsaturated fatty acids in fat-1 mice attenuated intestinal polyposis by either inhibiting COX-2/β-catenin signaling or activating 15-PGDH/IL-18

Omega-3 polyunsaturated fatty acids (ω-3PUFAs) have inhibitory effects in various preclinical cancer models, but their effects in intestinal polyposis have never been examined. As attempts have been made to use nutritional intervention to counteract colon cancer development, in this study we evaluated the effects of ω-3 PUFAs on intestinal polyposis in the Apc(Min/+) mouse model. The experimental groups included wild-type C56BL/6 mice, Apc(Min/+) mice, fat-1 transgenic mice expressing an n-3 desaturase to enable ω-3 PUFA synthesis, and Apc(Min/+) × fat-1 double-transgenic mice; all mice were 20 weeks of age. Small intestines were collected for gross and pathologic evaluation, including assessment of polyp number and size, followed by immunohistochemical staining and Western blotting. After administration of various concentrations of ω-3 PUFAs, PUFA levels were measured in small intestine tissue by GC/MS/MS analysis to compare with PUFA synthesis of between C57BL6 and fat-1mice. As a result, ω-3 PUFAs significantly attenuated Apc mutation-induced intestinal polyposis accompanied with significant inhibition of Wnt/β-catenin signaling, COX-2 and PGE2, but induced significant levels of 15-PGDH. In addition, significant induction of the inflammasome-related substrates as IL-1β and IL-18 and activation of caspase-1 was observed in Apc(Min/+) × fat-1 mice. Administration of at least 3 g/60 kg ω-3 PUFAs was equivalent to ω-3 PUFAs produced in fat-1 mice and resulted in significant increase in the expression of IL-1β, caspase-3 and IL-18, as seen in Apc(Min/+) × fat-1 mice. We conclude that ω-3PUFAs can prevent intestinal polyp formation by inhibition of Wnt/β-catenin signaling, but increased levels of 15-PGDH and IL-18.

Effect of Docosahexaenoic Acid on Cell Cycle Pathways in Breast Cell Lines With Different Transformation Degree

n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), abundant in fish, have been shown to affect development and progression of some types of cancer, including breast cancer. The aim of our study was to further analyze and clarify the effects of these nutrients on the molecular mechanisms underlying breast cancer. Following treatments with DHA we examined cell viability, death, cell cycle, and some molecular effects in breast cell lines with different transformation, phenotypic, and biochemical characteristics (MCF-10A, MCF-7, SK-BR-3, ZR-75-1). These investigations showed that DHA is able to affect cell viability, proliferation, and cell cycle progression in a different way in each assayed breast cell line. The activation of ERK1/2 and STAT3 pathways and the expression and/or activation of molecules involved in cell cycle regulation such as p21(Waf1/Cip1) and p53, are very differently regulated by DHA treatments in each cell model. DHA selectively: (i) arrests non tumoral MCF-10A breast cells in G0 /G1 cycle phase, activating p21(Waf1/Cip1) , and p53, (ii) induces to death highly transformed breast cells SK-BR-3, reducing ERK1/2 and STAT3 phosphorylation and (iii) only slightly affects each analyzed process in MCF-7 breast cell line with transformation degree lower than SK-BR-3 cells. These findings suggest a more relevant inhibitory role of DHA within early development and late progression of breast cancer cell transformation and a variable effect in the other phases, depending on individual molecular properties and degree of malignancy of each clinical case.

Modulation of Breast Cancer Risk Biomarkers by High-Dose Omega-3 Fatty Acids: Phase II Pilot Study in Premenopausal Women

Higher intakes of the omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid (AA) have been variably associated with reduced risk of premenopausal breast cancer. The purpose of this pilot trial was to assess feasibility and explore the effects of high-dose EPA and DHA on blood and benign breast tissue risk biomarkers before design of a placebo-controlled phase IIB trial. Premenopausal women with evidence of hyperplasia ± atypia by baseline random periareolar fine needle aspiration were given 1860 mg of EPA + 1500 mg of DHA ethyl esters daily for 6 months. Blood and benign breast tissue were sampled during the same menstrual cycle phase prestudy and a median of 3 weeks after last dose. Additional blood was obtained within 24 hours of last dose. Feasibility, which was predefined as 50% uptake, 85% retention, and 70% compliance, was demonstrated with 46% uptake, 94% completion, and 85% compliance. Cytologic atypia decreased from 77% to 38% (P = 0.002), and Ki-67 from a median of 2.1% to 1.0% (P = 0.021) with an increase in the ratio of EPA + DHA to AA in erythrocyte phospholipids but no change in blood hormones, adipokines, or cytokines. Exploratory breast proteomics assessment showed decreases in several proteins involved in hormone and cytokine signaling with mixed effects on those in the AKT/mTOR pathways. Further investigation of EPA plus DHA for breast cancer prevention in a placebo-controlled trial in premenopausal women is warranted.

Modulation of Breast Cancer Risk Biomarkers by High-Dose Omega-3 Fatty Acids: Phase II Pilot Study in Postmenopausal Women

Associational studies suggest higher intakes/blood levels of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid (AA) are associated with reduced breast cancer risk. We performed a pilot study of high-dose EPA + DHA in postmenopausal women to assess feasibility before initiating a phase IIB prevention trial. Postmenopausal women with cytologic evidence of hyperplasia in their baseline random periareolar fine needle aspiration (RPFNA) took 1,860 mg EPA +1500 mg DHA ethyl esters daily for 6 months. Blood and breast tissue were sampled at baseline and study conclusion for exploratory biomarker assessment, with P values uncorrected for multiple comparisons. Feasibility was predefined as 50% uptake, 80% completion, and 70% compliance. Trial uptake by 35 study entrants from 54 eligible women was 65%, with 97% completion and 97% compliance. Favorable modulation was suggested for serum adiponectin (P = 0.0027), TNFα (P = 0.016), HOMA 2B measure of pancreatic β cell function (P = 0.0048), and bioavailable estradiol (P = 0.039). Benign breast tissue Ki-67 (P = 0.036), macrophage chemoattractant protein-1 (P = 0.033), cytomorphology index score (P = 0.014), and percent mammographic density (P = 0.036) were decreased with favorable effects in a proteomics array for several proteins associated with mitogen signaling and cell-cycle arrest; but no obvious overall effect on proteins downstream of mTOR. Although favorable risk biomarker modulation will need to be confirmed in a placebo-controlled trial, we have demonstrated feasibility for development of high-dose EPA and DHA ethyl esters for primary prevention of breast cancer.

α-linolenic acid and docosahexaenoic acid, alone and combined with trastuzumab, reduce HER2-overexpressing breast cancer cell growth but differentially regulate HER2 signaling pathways

BACKGROUND

Diets rich in the n-3 fatty acid alpha-linolenic acid (ALA) have been shown to reduce breast tumor growth, enhance the effectiveness of the HER2-targeted drug trastuzumab (TRAS) and reduce HER2 signaling in mouse models. It is unclear whether this is due to direct effects of ALA or due to its long-chain n-3 fatty acids metabolites including docosahexaenoic acid (DHA).

METHODS

The ability of HER2-overexpressing BT-474 human breast cancer cells to convert ALA to long-chain n-3 fatty acids was determined by measurement of phospholipid fatty acids by gas chromatography following treatment with 100 μM ALA. The effects of 96 h treatment with ALA or DHA, at serum levels seen in mice (50-100 μM), alone and combined with TRAS (10 μg/ml), on BT-474 cell growth measured by trypan blue exclusion, apoptosis measured by flow cytometric analysis of Annexin-V/7-AAD stained cells (ALA and TRAS treatment only) and protein biomarkers HER2 signaling measured by western blot were determined.

RESULTS

ALA-treated BT-474 cells had higher phospholipid ALA but no increase in downstream n-3 metabolites including DHA. Both ALA and DHA reduced cell growth with and without TRAS. ALA had no effect on apoptosis. ALA and DHA showed opposite effects on Akt and MAPK phosphorylation; ALA increased and DHA decreased phosphorylation.

CONCLUSIONS

Together these data suggest that, while both ALA and its DHA metabolite can reduce HER2-overexpressing breast cancer growth with and without TRAS, they demonstrate for the first time that DHA is responsible for the effects of ALA-rich diets on HER2 signaling pathways.

The effects of omega-3 polyunsaturated Fatty Acid consumption on mammary carcinogenesis

The consumption of omega-3 polyunsaturated fatty acids (n-3 PUFA) is associated with a reduced risk of breast cancer. Studies in animals and in vitro have demonstrated mechanisms that could explain this apparent effect, but clinical and epidemiological studies have returned conflicting results on the practical benefits of dietary n-3 PUFA for prevention of breast cancer. Effects are often only significant within a population when comparing the highest n-3 PUFA consumption group to the lowest n-3 group or highest n-6 group. The beneficial effects of n-3 PUFA eicosapentaenoic and docosahexaenoic on the risk of breast cancer are dose dependent and are negatively affected by total n-6 consumption. The majority of the world population, including the most highly developed regions, consumes insufficient n-3 PUFA to significantly reduce breast cancer risk. This review discusses the physiological and dietary context in which reduction of breast cancer risk may occur, some proposed mechanisms of action and meaningful recommendations for consumption of n-3 PUFA in the diet of developed regions.

The use of genetic engineering techniques to improve the lipid composition in meat, milk and fish products: a review

The health-promoting properties of dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFAs) for humans are well-known. Products of animal-origin enriched with n-3 LCPUFAs can be a good example of functional food, that is food that besides traditionally understood nutritional value may have a beneficial influence on the metabolism and health of consumers, thus reducing the risk of various lifestyle diseases such as atherosclerosis and coronary artery disease. The traditional method of enriching meat, milk or eggs with n-3 LCPUFA is the manipulation of the composition of animal diets. Huge progress in the development of genetic engineering techniques, for example transgenesis, has enabled the generation of many kinds of genetically modified animals. In recent years, one of the aims of animal transgenesis has been the modification of the lipid composition of meat and milk in order to improve the dietetic value of animal-origin products. This article reviews and discusses the data in the literature concerning studies where techniques of genetic engineering were used to create animal-origin products modified to contain health-promoting lipids. These studies are still at the laboratory stage, but their results have demonstrated that the transgenesis of pigs, cows, goats and fishes can be used in the future as efficient methods of production of healthy animal-origin food of high dietetic value. However, due to high costs and a low level of public acceptance, the introduction of this technology to commercial animal production and markets seems to be a distant prospect.

n-3 polyunsaturated fatty acids and mechanisms to mitigate inflammatory paracrine signaling in obesity-associated breast cancer

Globally, the prevalence of obesity is increasing which subsequently increases the risk of the development of obesity-related chronic diseases. Low-grade chronic inflammation and dysregulated adipose tissue inflammatory mediator/adipokine secretion are well-established in obesity, and these factors increase the risk of developing inflammation-associated cancer. Breast cancer is of particular interest given that increased inflammation within the subcutaneous mammary adipose tissue depot can alter the local tissue inflammatory microenvironment such that it resembles that of obese visceral adipose tissue. Therefore, in obese women with breast cancer, increased inflammatory mediators both locally and systemically can perpetuate inflammation-associated pro-carcinogenic signaling pathways, thereby increasing disease severity. Herein, we discuss some of these inflammation-associated pro-carcinogenic mechanisms of the combined obese breast cancer phenotype and offer evidence that dietary long chain n-3 polyunsaturated fatty acids (PUFA) may have utility in mitigating the severity of obesity-associated inflammation and breast cancer.

Effects of fish oil with a high content of n-3 polyunsaturated fatty acids on mouse gut microbiota

BACKGROUND AND AIMS

Many studies show that fish oil with high content of n-3 polyunsaturated fatty acids (PUFAs) plays an important role in human health and disease. But the effects of fish oil with high content of PUFAs on gut microbiota, which are also known play a significant role in several human diseases, is not clear. In the present study we evaluated the effects of fish oil with high content of n-3 PUFAs on gut microbiota.

METHODS

Changes in gut microbiota in ICR mice after supplementation of fish oil (containing eicosapentaenoic acid and docosahexaenoic acid: ∼40 and 27% respectively) for 15 days was characterized using the hypervariable V3 region of the 16 rRNA gene-based polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) profiling, DNA sequencing, and phylogenetic analysis techniques.

RESULTS

Fish oil treatment resulted in a decrease in Helicobacter, Uncultured bacterium clone WD2_aaf07d12 (GenBank: EU511712.1), Clostridiales bacterium, Sphingomonadales bacterium and Pseudomonas species Firmicutes, and several uncultured bacteria.

CONCLUSIONS

Fish oil with a high content of n-3 PUFAs are capable of producing significant changes in the gut microbiota that may, at least in part, explain the health benefits or injury induced by fish oil use.

Prostaglandin E3 metabolism and cancer

The anticancer activity of n-3 fatty acids, especially those derived from fish, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid) (DHA), has been studied for centuries. While there is a growing body of evidence that EPA and DHA may influence cancer initiation and development through targeting multiple events of tumor development, the underlying mechanisms responsible for these activities are still not fully understood. A number of studies have suggested that the anticancer activities of EPA and DHA are associated with their effects on eicosanoid metabolism by which they inhibit prostaglandin E2 (PGE2) production. In contrast to DHA, EPA can function as a substrate for cyclooxygenases (COXs) to synthesize unique 3-series prostaglandin compounds, especially PGE3. With advance technology in mass spectrometry, there is renewed interest in studying the role of PGE3 in EPA elicited anti-proliferative activity in various cancers, with some promising results. Here, we summarize the regulation of PGE3 synthesis in cancer cells and its role in EPA elicited anticancer activity. The development of PGE3 and its metabolites as potential biomarkers for future clinical evaluation of EPA and fish oil in cancer care is discussed.