Inhibition of neuroblastoma cell proliferation with omega-3 fatty acids and treatment of a murine model of human neuroblastoma using a diet enriched with omega-3 fatty acids in combination with sunitinib

Enhancing cancer immunotherapy via inhibition of soluble epoxide hydrolase

Cancer therapy, including immunotherapy, is inherently limited by chronic inflammation-induced tumorigenesis and toxicity within the tumor microenvironment. Thus, stimulating the resolution of inflammation may enhance immunotherapy and improve the toxicity of immune checkpoint inhibition (ICI). As epoxy-fatty acids (EpFAs) are degraded by the enzyme soluble epoxide hydrolase (sEH), the inhibition of sEH increases endogenous EpFA levels to promote the resolution of cancer-associated inflammation. Here, we demonstrate that systemic treatment with ICI induces sEH expression in multiple murine cancer models. Dietary omega-3 polyunsaturated fatty acid supplementation and pharmacologic sEH inhibition, both alone and in combination, significantly enhance anti-tumor activity of ICI in these models. Notably, pharmacological abrogation of the sEH pathway alone or in combination with ICI counter-regulates an ICI-induced pro-inflammatory and pro-tumorigenic cytokine storm. Thus, modulating endogenous EpFA levels through dietary supplementation or sEH inhibition may represent a unique strategy to enhance the anti-tumor activity of paradigm cancer therapies.

FABP7 Facilitates Uptake of Docosahexaenoic Acid in Glioblastoma Neural Stem-like Cells

Glioblastoma (GBM) is an aggressive tumor with a dismal prognosis. Neural stem-like cells contribute to GBM's poor prognosis by driving drug resistance and maintaining cellular heterogeneity. GBM neural stem-like cells express high levels of brain fatty acid-binding protein (FABP7), which binds to polyunsaturated fatty acids (PUFAs) ω-6 arachidonic acid (AA) and ω-3 docosahexaenoic acid (DHA). Similar to brain, GBM tissue is enriched in AA and DHA. However, DHA levels are considerably lower in GBM tissue compared to adult brain. Therefore, it is possible that increasing DHA content in GBM, particularly in neural stem-like cells, might have therapeutic value. Here, we examine the fatty acid composition of patient-derived GBM neural stem-like cells grown as neurosphere cultures. We also investigate the effect of AA and DHA treatment on the fatty acid profiles of GBM neural stem-like cells with or without FABP7 knockdown. We show that DHA treatment increases DHA levels and the DHA:AA ratio in GBM neural stem-like cells, with FABP7 facilitating the DHA uptake. We also found that an increased uptake of DHA inhibits the migration of GBM neural stem-like cells. Our results suggest that increasing DHA content in the GBM microenvironment may reduce the migration/infiltration of FABP7-expressing neural stem-like cancer cells.

Omega-3 Fatty Acids and Their Role in Pediatric Cancer

BACKGROUND

Malnutrition is common in children with cancer and is associated with adverse clinical outcomes. The need for supportive care is becoming ever more evident and the role of nutrition in oncology is still not sufficiently understood. In particular, the consequences of macro- and micronutrient deficiencies require further research. As epidemiological data suggest anti-tumoral properties of omega-3 (n-3) polyunsaturated fatty acids (PUFAs), we reviewed the role of nutrition and n-3 supplementation in pediatric oncology.

METHODS

A comprehensive literature search was conducted on PubMed through 5 February 2021 to select meta-analyses, systematic reviews, observational studies, and individual randomized controlled trials (RCTs) on macro- and micronutrient supplementation in pediatric oncology. The search strategy included the following medical subject headings (MeSH) and keywords: "childhood cancer", "pediatric oncology", "nutritional status", "malnutrition", and "omega-3-fatty-acids". The reference lists of all relevant articles were screened to include potentially pertinent studies.

RESULTS

We summarize evidence about the importance of adequate nutrition in childhood cancer and the role of n-3 PUFAs and critically interpret findings. Possible effects of supplementation on the nutritional status and benefits during chemotherapy are discussed as well as strategies for primary and secondary prevention.

CONCLUSION

We here describe the obvious benefits of omega-3 supplementation in childhood cancer. Further large scale clinical trials are required to verify potential anti-cancer effects of n-3 fatty acids.

Cancer diets for cancer patients: Lessons from mouse studies and new insights from the study of fatty acid metabolism in tumors

Specific diets for cancer patients have the potential to offer an adjuvant modality to conventional anticancer therapy. If the concept of starving cancer cells from nutrients to inhibit tumor growth is quite simple, the translation into the clinics is not straightforward. Several diets have been described including the Calorie-restricted diet based on a reduction in carbohydrate intake and the Ketogenic diet wherein the low carbohydrate content is compensated by a high fat intake. As for other diets that deviate from normal composition only by one or two amino acids, these diets most often revealed a reduction in tumor growth in mice, in particular when associated with chemo- or radiotherapy. By contrast, in cancer patients, the interest of these diets is almost exclusively supported by case reports precluding any conclusions on their real capacity to influence disease outcome. In parallel, the field of tumor lipid metabolism has emerged in the last decade offering a better understanding of how fatty acids are captured, synthesized or stored as lipid droplets in cancers. Fatty acids participate to cancer cell survival in the hypoxic and acidic tumor microenvironment and also support proliferation and invasiveness. Interestingly, while such addiction for fatty acids may account for cancer progression associated with high fat diet, it could also represent an Achilles heel for tumors. In particular n-3 polyunsaturated fatty acids represent a class of lipids that can exert potent cytotoxic effects in tumors and therefore represent an attractive diet supplementation to improve cancer patient outcomes.

The Effect of Omega-3 Polyunsaturated Fatty Acid Supplementations on anti-Tumor Drugs in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) comprises about 10-20% of all diagnosed breast cancers. Increasing evidence shows that the omega-3 polyunsaturated fatty acids (ω-3PUFAs), docosahexaenoic acid and eicosapentaenoic acid, can influence the development, progression, and prognosis of TNBC In Vivo and In Vitro; however, clinical evidence supporting the effect of ω-3PUFAs on TNBC is lacking. Research has demonstrated that ω-3PUFAs can induce apoptosis in breast cancer cells by inhibiting the PI3K/AKT signal transduction pathway, and that ω-3PUFAs can improve the effectiveness of chemotherapy drugs. Using ω-3PUFA supplementation in addition to pharmacotherapy in the treatment of breast cancer may result in enhanced anti-tumor effects that will be particularly applicable to difficult to treat phenotypes such as TNBC. The aim of the current review was to summarize the evidence-base supporting the antitumor effects of omega-3 PUFAs in TNBC.

Addition of docosahexaenoic acid synergistically enhances the efficacy of apatinib for triple-negative breast cancer therapy

The current study aimed to investigate the antitumor and antiangiogenesis effects of apatinib in triple-negative breast cancer in vitro and also whether the combination of docosahexaenoic acid (DHA) and apatinib is more effective than apatinib monotherapy. The cell counting kit-8 assay was used to measure cell proliferation. Flow cytometry was utilized to determine the cell apoptosis rate. A wound healing assay was utilized to assess cell migration. Western blot analysis was carried out to determine the effects of apatinib and DHA on Bcl-2, BAX, cleaved caspase-3, caspase-3, phosphorylated protein kinase B (p-Akt), and Akt expression. DHA in combination with apatinib showed enhanced inhibitory effects on cell proliferation and migration compared with apatinib or DHA monotherapy. Meanwhile, DHA combined with apatinib strongly increased the cell apoptosis percentage. DHA was observed to enhance the antitumor and antiangiogenesis effects of apatinib via further downregulation of p-Akt expression.Abbreviations: FITC: fluorescein isothiocyanate; PI: propidium iodide.

Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits

Omega-3 polyunsaturated fatty acids (PUFAs) include α-linolenic acid (ALA; 18:3 ω-3), stearidonic acid (SDA; 18:4 ω-3), eicosapentaenoic acid (EPA; 20:5 ω-3), docosapentaenoic acid (DPA; 22:5 ω-3), and docosahexaenoic acid (DHA; 22:6 ω-3). In the past few decades, many epidemiological studies have been conducted on the myriad health benefits of omega-3 PUFAs. In this review, we summarized the structural features, properties, dietary sources, metabolism, and bioavailability of omega-3 PUFAs and their effects on cardiovascular disease, diabetes, cancer, Alzheimer's disease, dementia, depression, visual and neurological development, and maternal and child health. Even though many health benefits of omega-3 PUFAs have been reported in the literature, there are also some controversies about their efficacy and certain benefits to human health.

Secreted protein acidic and rich in cysteine (SPARC) induces lipotoxicity in neuroblastoma by regulating transport of albumin complexed with fatty acids

SPARC is a matrix protein that mediates interactions between cells and the microenvironment. In cancer, SPARC may either promote or inhibit tumor growth depending upon the tumor type. In neuroblastoma, SPARC is expressed in the stromal Schwannian cells and functions as a tumor suppressor. Here, we developed a novel in vivo model of stroma-rich neuroblastoma using non-tumorigenic SHEP cells with modulated levels of SPARC, mixed with tumorigenic KCNR cells. Tumors with stroma-derived SPARC displayed suppressed growth, inhibited angiogenesis and increased lipid accumulation. Based on the described chaperone function of SPARC, we hypothesized that SPARC binds albumin complexed with fatty acids and transports them to tumors. We show that SPARC binds albumin with Kd=18.9±2.3 uM, and enhances endothelial cell internalization and transendothelial transport of albumin in vitro. We also demonstrate that lipids induce toxicity in neuroblastoma cells and show that lipotoxicity is increased when cells are cultured in hypoxic conditions. Studies investigating the therapeutic potential of SPARC are warranted.

ω-3 Long Chain Polyunsaturated Fatty Acids as Sensitizing Agents and Multidrug Resistance Revertants in Cancer Therapy

Chemotherapy efficacy is strictly limited by the resistance of cancer cells. The ω-3 long chain polyunsaturated fatty acids (ω-3 LCPUFAs) are considered chemosensitizing agents and revertants of multidrug resistance by pleiotropic, but not still well elucidated, mechanisms. Nowadays, it is accepted that alteration in gene expression, modulation of cellular proliferation and differentiation, induction of apoptosis, generation of reactive oxygen species, and lipid peroxidation are involved in ω-3 LCPUFA chemosensitizing effects. A crucial mechanism in the control of cell drug uptake and efflux is related to ω-3 LCPUFA influence on membrane lipid composition. The incorporation of docosahexaenoic acid in the lipid rafts produces significant changes in their physical-chemical properties affecting content and functions of transmembrane proteins, such as growth factors, receptors and ATP-binding cassette transporters. Of note, ω-3 LCPUFAs often alter the lipid compositions more in chemoresistant cells than in chemosensitive cells, suggesting a potential adjuvant role in the treatment of drug resistant cancers.

Role of diets rich in omega-3 and omega-6 in the development of cancer

Over the past decade, some studies have addressed the therapeutic effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and the opposite effects of omega-6 (ω-6) PUFAs on several diseases, including cardiovascular disorders, diabetes, neurodegenerative diseases, and cancer. Research demonstrates the safety of these naturally occurring ingredients. Of particular interest, several studies have shown that ω-3 PUFAs possess a therapeutic role against certain types of cancer. It is also known that ω-3 PUFAs can improve the efficacy and tolerability of chemotherapy. Previous reports have indicated that suppression of nuclear factor-κB, activation of AMPK/SIRT1, modulation of cyclooxygenase (COX) activity, and up-regulation of novel anti-inflammatory lipid mediators such as protectins, maresins, and resolvins, are the main mechanisms of the antineoplastic effect of ω-3 PUFAs. In contrast, several studies have demonstrated that ω-6 PUFAs induce progression in certain types of cancer. In this review, we discuss epidemiological and experimental studies addressing the relationship between the development of some types of cancer, including colon and colorectal carcinoma, breast cancer, prostate cancer, lung cancer and neuroblastoma, and the ingestion to ω-3 and ω-6 (PUFAs). We also discuss the clinical data, addressing the therapeutic role of omega-3 PUFA against different types of cancer.

Docosahexaenoic acid liposomes for targeting chronic inflammatory diseases and cancer: an in vitro assessment

Inflammation, oxidative stress, and uncontrolled cell proliferation are common key features of chronic inflammatory diseases, such as atherosclerosis and cancer. ω3 polyunsaturated fatty acids (PUFAs; also known as omega3 fatty acids or fish oil) have beneficial effects against inflammation upon dietary consumption. However, these effects cannot be fully exploited unless diets are enriched with high concentrations of fish oil supplements over long periods of time. Here, a nanomedicine-based approach is presented for delivering effective levels of PUFAs to inflammatory cells. Nanoparticles are internalized by immune cells, and hence can adequately deliver bioactive lipids into these target cells. The ω3 FA docosahexaenoic acid was formulated into liposomes (ω-liposomes), and evaluated for anti-inflammatory effects in different types of immune cells. ω-Liposomes strongly inhibited the release of reactive oxygen species and reactive nitrogen species from human neutrophils and murine macrophages, and also inhibited the production of the proinflammatory cytokines TNFα and MCP1. Moreover, ω-liposomes inhibited tumor-cell proliferation when evaluated in FaDu head and neck squamous carcinoma and 4T1 breast cancer cells in in vitro cultures. We propose that ω-liposomes are a promising nanonutraceutical formulation for intravenous delivery of fish oil FAs, which may be beneficial in the treatment of inflammatory disorders and cancer.

How plausible is the use of dietary n-3 PUFA in the adjuvant therapy of cancer?

Considerable debate exists regarding the potential antineoplastic effect of dietary long-chain n-3 PUFA contained in fatty fishes. Since the majority of published data has proven that their intake does not induce toxic or carcinogenic effects in humans, their possible preventive use against cancer has been suggested. On the other hand, it is unlikely that they could be effective in cancer patients as a single therapy. Nevertheless, a considerable effort has been put forth in recent years to evaluate the hypothesis that n-3 PUFA might improve the antineoplastic efficiency of currently used anticancer agents. The rationale for this therapeutic combinatory strategy is trying to increase cancer sensitivity to conventional therapies. This could allow the use of lower drug/radiation doses and, thereby, a reduction in the detrimental health effects associated with these treatments. We will here critically examine the studies that have investigated this possibility, by focusing particularly on the biological and molecular mechanisms underlying the antineoplastic effect of these combined treatments. A possible use of n-3 PUFA in combination with the innovative single-targeted anti-cancer therapies, that often are not completely devoid of dangerous side-effects, is also suggested.

Accumulation of eicosapolyenoic acids enhances sensitivity to abscisic acid and mitigates the effects of drought in transgenic Arabidopsis thaliana

IgASE1, a C₁₈ Δ(9)-specific polyunsaturated fatty acid elongase from the marine microalga Isochrysis galbana, is able to convert linoleic acid and α-linolenic acid to eicosadienoic acid and eicosatrienoic acid in Arabidopsis. Eicosadienoic acid and eicosatrienoic acid are precursors of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which are synthesized via the Δ(8) desaturation biosynthetic pathways. This study shows that the IgASE1-expressing transgenic Arabidopsis exhibited altered morphology (decreased leaf area and biomass) and enhanced drought resistance compared to wild-type plants. The transgenic Arabidopsis were hypersensitive to abscisic acid (ABA) during seed germination, post-germination growth, and seedling development. They had elevated leaf ABA levels under well-watered and dehydrated conditions and their stomata were more sensitive to ABA. Exogenous application of eicosadienoic acid and eicosatrienoic acid can mimic ABA and drought responses in the wild type plants, similar to that found in the transgenic ones. The transcript levels of genes involved in the biosynthesis of ABA (NCED3, ABA1, AAO3) as well as other stress-related genes were upregulated in this transgenic line upon osmotic stress (300 mM mannitol). Taken together, these results indicate that these two eicosapolyenoic acids or their derived metabolites can mitigate the effects of drought in transgenic Arabidopsis, at least in part, through the action of ABA.