Omega-3 fatty acid is a potential preventive agent for recurrent colon cancer

Dysregulation of cellular membrane homeostasis as a crucial modulator of cancer risk

Cellular membranes serve as an epicentre combining extracellular and cytosolic components with membranous effectors, which together support numerous fundamental cellular signalling pathways that mediate biological responses. To execute their functions, membrane proteins, lipids and carbohydrates arrange, in a highly coordinated manner, into well-defined assemblies displaying diverse biological and biophysical characteristics that modulate several signalling events. The loss of membrane homeostasis can trigger oncogenic signalling. More recently, it has been documented that select membrane active dietaries (MADs) can reshape biological membranes and subsequently decrease cancer risk. In this review, we emphasize the significance of membrane domain structure, organization and their signalling functionalities as well as how loss of membrane homeostasis can steer aberrant signalling. Moreover, we describe in detail the complexities associated with the examination of these membrane domains and their association with cancer. Finally, we summarize the current literature on MADs and their effects on cellular membranes, including various mechanisms of dietary chemoprevention/interception and the functional links between nutritional bioactives, membrane homeostasis and cancer biology.

Molecular Mechanisms Associated with the Inhibitory Role of Long Chain n-3 PUFA in Colorectal Cancer

Colorectal cancer (CRC) is the third leading cause of cancer-related death in the world. Multiple evidence suggests that there is an association between excess fat consumption and the risk of CRC. The long chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential for human health, and both in vitro and in vivo studies have shown that these fatty acids can prevent CRC development through various molecular mechanisms. These include the modulation of arachidonic acid (AA) derived prostaglandin synthesis, alteration of growth signaling pathways, arrest of the cell cycle, induction of cell apoptosis, suppression of angiogenesis and modulation of inflammatory response. Human clinical studies found that LC n-3 PUFA combined with chemotherapeutic agents can improve the efficacy of treatment and reduce the dosage of chemotherapy and associated side effects. In this review, we discuss comprehensively the anti-cancer effects of LC n-3 PUFA on CRC, with a main focus on the underlying molecular mechanisms.

The Salmon Oil OmeGo Reduces Viability of Colorectal Cancer Cells and Potentiates the Anti-Cancer Effect of 5-FU

Colorectal cancer (CRC) is one of the most common cancer types worldwide. Chemotherapy is toxic to normal cells, and combinatory treatment with natural well-tolerated products is being explored. Some omega-3 polyunsaturated fatty acids (n-3 PUFAs) and marine fish oils have anti-cancer effects on CRC cells. The salmon oil OmeGo (Hofseth BioCare) contains a spectrum of fatty acids, including the n-3 PUFAs docosahexaenoic acid (DHA) and eicosahexaenoic acid (EPA). We explored a potential anti-cancer effect of OmeGo on the four CRC cell lines DLD-1, HCT-8, LS411N, and LS513, alone and in combination with the chemotherapeutic agent 5-Fluorouracil (5-FU). Screening indicated a time- and dose-dependent effect of OmeGo on the viability of the DLD-1 and LS513 CRC cell lines. Treatment with 5-FU and OmeGo (IC20-IC30) alone indicated a significant reduction in viability. A combinatory treatment with OmeGo and 5-FU resulted in a further reduction in viability in DLD-1 and LS513 cells. Treatment of CRC cells with DHA + EPA in a concentration corresponding to the content in OmeGo alone or combined with 5-FU significantly reduced viability of all four CRC cell lines tested. The lowest concentration of OmeGo reduced viability to a higher degree both alone and in combination with 5-FU compared to the corresponding concentrations of DHA + EPA in three of the cell lines. Results suggest that a combination of OmeGo and 5-FU could have a potential as an alternative anti-cancer therapy for patients with CRC.

Cancer Metabolism as a Therapeutic Target and Review of Interventions

Cancer is amenable to low-cost treatments, given that it has a significant metabolic component, which can be affected through diet and lifestyle change at minimal cost. The Warburg hypothesis states that cancer cells have an altered cell metabolism towards anaerobic glycolysis. Given this metabolic reprogramming in cancer cells, it is possible to target cancers metabolically by depriving them of glucose. In addition to dietary and lifestyle modifications which work on tumors metabolically, there are a panoply of nutritional supplements and repurposed drugs associated with cancer prevention and better treatment outcomes. These interventions and their evidentiary basis are covered in the latter half of this review to guide future cancer treatment.

The comparative anti-cancer effects of krill oil and oxaliplatin in an orthotopic mouse model of colorectal cancer

BACKGROUND

Our in vitro studies demonstrated that krill oil (KO) has anti-cancer potential. This study aimed to compare the anti-cancer effects of KO with a commonly used chemotherapeutic drug, oxaliplatin and to identify the molecular mechanisms associated with KO supplementation in a mouse model of colorectal cancer (CRC).

METHODS

Thirty-six male Balb/c mice were randomly divided into six groups. Five groups received standard chow diet supplemented with KO (150 g/kg)), corn oil (150 g/kg), KO combined with ½ dose of oxaliplatin (1.5 mg/kg body weight/3 times per week), corn oil combined with ½ dose of oxaliplatin (1.5 mg/kg body weight/3 times per week), or a full dose of oxaliplatin (3 mg/kg body weight/3 times per week). The control (sham) group received a standard chow diet. Treatments started three weeks before and continued for three weeks after orthotopic CRC induction. The number of metastases, tumour weight and volume were quantified ex-vivo. The expression of cytochrome c, cleaved caspase-9 and -3, DNA damage, PD-L1, PD-L2 and HSP-70 were determined.

RESULTS

A significant reductions in the weight and volume of tumours were observed in mice treated with KO and KO plus a ½ dose of oxaliplatin compared to the sham group, similar to oxaliplatin-treated mice. KO, and KO plus ½ dose of oxaliplatin significantly increased the expression of cytochrome c, cleaved caspase-9 and -3, and DNA damage and decreased expression of PD-L1, PD-L2 and HSP-70 in tumour tissues compared to the sham group.

CONCLUSIONS

The in vivo anti-cancer effects of KO are comparable with oxaliplatin. Thus, dietary KO supplementation has a great potential as a therapeutic/adjunctive agent for CRC treatment.

Cancer Stem Cells: Metabolic Characterization for Targeted Cancer Therapy

The subpopulation of cancer stem cells (CSCs) within tumor bulk are known for tumor recurrence and metastasis. CSCs show intrinsic resistance to conventional therapies and phenotypic plasticity within the tumor, which make these a difficult target for conventional therapies. CSCs have different metabolic phenotypes based on their needs as compared to the bulk cancer cells. CSCs show metabolic plasticity and constantly alter their metabolic state between glycolysis and oxidative metabolism (OXPHOS) to adapt to scarcity of nutrients and therapeutic stress. The metabolic characteristics of CSCs are distinct compared to non-CSCs and thus provide an opportunity to devise more effective strategies to target CSCs. Mechanism for metabolic switch in CSCs is still unravelled, however existing evidence suggests that tumor microenvironment affects the metabolic phenotype of cancer cells. Understanding CSCs metabolism may help in discovering new and effective clinical targets to prevent cancer relapse and metastasis. This review summarises the current knowledge of CSCs metabolism and highlights the potential targeted treatment strategies.

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.

Selectively targeting cancer stem cells: Current and novel therapeutic strategies and approaches in the effective eradication of cancer

Cancer stem cells (CSCs) are a subgroup of cells in malignant cancers, which possess self-renewal capacity, tumor-initiating capability, and pluripotency, as well as being responsible for tumor maintenance, metastasis, relapse, and chemoresistance. The treatment modalities previously established for cancer included surgery, chemotherapy, and radiotherapy. The majority of tumor cells of non-CSCs could be eradicated using conventional chemotherapy and radiotherapy. Therefore, novel and promising therapeutic strategies that selectively target CSCs are of great importance. In this review, we described different therapeutic strategies such as immunotherapy, metabolism-based therapeutic strategies, and additional potential therapeutic approaches (targeting microRNAs [miRNAs], histone deacetylase, and DNA methyl transferase) against CSCs. Taken together, due to the inefficiency of anticancer single therapies, targeting CSCs through their metabolism and using immunotherapy and miRNAs besides classical chemo- and radiotherapy may exert better therapeutic effects.

Synergistic anticancer effect of docosahexaenoic acid and isoliquiritigenin on human colorectal cancer cells through ROS-mediated regulation of the JNK and cytochrome c release

A large body of research has demonstrated a synergistic anticancer effect between docosahexaenoic acid (DHA) and standard chemotherapy regimens against colorectal cancer (CRC). In this study, we investigated the chemotherapeutic potential of cotreatment with DHA and isoliquiritigenin (ISL) against CRC HCT-116 cells. Apoptosis was confirmed by Annexin V/PI staining and expression of apoptosis-associated proteins. The synergistic effect of DHA and ISL combination on apoptosis was detected using combination index approaches. Flow cytometry was carried out using fluorescent probes to measure the production of reactive oxygen species (ROS). DHA and ISL in combination synergistically enhanced the decrease in cell viability versus the compounds used alone. Moreover, we demonstrated that the synergistic anti-CRC activity of cotreatment with these two compounds was achieved by inducing the apoptosis caspase-dependently mediated through augmented ROS generation followed by increased Fas ligand mRNA expression and cytochrome c release. Our data also demonstrated that cotreating with DHA and ISL strongly upregulated the phosphorylation of ERK and JNK, which are functionally associated with ROS induced by the two compounds in combination. Interestingly, further study revealed that inhibiting ERK phosphorylation strongly enhanced Fas ligand mRNA expression and the combination of the two compounds induced stronger cytotoxicity, whereas inhibiting JNK phosphorylation significantly reduced the apoptotic signals mediated by cotreatment with these two compounds. Excessive ROS-induced JNK activation and cytochrome c release from mitochondria played a key role in the synergistic anticancer activity of CRC cells by cotreating with DHA and ISL.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Long-term outcomes after perioperative treatment with omega-3 fatty acid supplements in colorectal cancer

Background

This study aimed to evaluate the effect of perioperative supplementation with omega‐3 fatty acids (n‐3 FA) on perioperative outcomes and survival in patients undergoing colorectal cancer surgery.

Methods

Patients scheduled for elective resection of colorectal cancer between 2007 and 2010 were randomized to either an n‐3 FA‐enriched oral nutrition supplement (ONS) twice daily or a standard ONS (control) for 7 days before and after surgery. Outcome measures, including postoperative complications, 3‐year cumulative incidence of local or metastatic colorectal cancer recurrence and 5‐year overall survival, were compared between the groups.

Results

Of 148 patients enrolled in the study, 125 (65 patients receiving n‐3 FA‐enriched ONS and 60 receiving standard ONS) were analysed. There were no differences in postoperative complications after surgery (P = 0·544). The risk of disease recurrence at 3 years was similar (relative risk 1·66, 95 per cent c.i. 0·65 to 4·26).The 5‐year survival rate of patients treated with n‐3 FA was 69·2 (95 per cent c.i. 56·5 to 78·9) per cent, compared with 81·7 (69·3 to 89·4) per cent in the control group (P = 0·193). After adjustment for age, stage of disease and adjuvant chemotherapy, n‐3 FA was associated with higher mortality compared with controls (hazard ratio 1·73, 95 per cent c.i. 1·06 to 2·83; P = 0·029). The interaction between n‐3 FA and adjuvant chemotherapy was not statistically significant.

Conclusion

Perioperative supplementation with n‐3 FA did not confer a survival benefit in patients undergoing colorectal cancer surgery. n‐3 FA did not benefit the subgroup of patients treated with adjuvant chemotherapy or decrease the risk of disease recurrence.

Polyunsaturated fatty acids and DNA methylation in colorectal cancer

Colorectal cancer (CRC) has been designated a major global problem, especially due to its high prevalence in developed countries. CRC mostly occurs sporadically (75%-80%), and only 20%-25% of patients have a family history. Several processes are involved in the development of CRC such as a combination of genetic and epigenetic alterations. Epigenetic changes, including DNA methylation play a vital role in the progression of CRC. Complex interactions between susceptibility genes and environmental factors, such as a diet and sedentary lifestyle, lead to the development of CRC. Clinical and experimental studies have confirmed the beneficial effects of dietary polyunsaturated fatty acids (PUFAs) in preventing CRC. From a mechanistic viewpoint, it has been suggested that PUFAs are pleiotropic agents that alter chromatin remodeling, membrane structure and downstream cell signaling. Moreover, PUFAs can alter the epigenome via modulation of DNA methylation. In this review, we summarize recent investigations linking PUFAs and DNA methylation-associated CRC risk.

Functional link between plasma membrane spatiotemporal dynamics, cancer biology, and dietary membrane-altering agents

The cell plasma membrane serves as a nexus integrating extra- and intracellular components, which together enable many of the fundamental cellular signaling processes that sustain life. In order to perform this key function, plasma membrane components assemble into well-defined domains exhibiting distinct biochemical and biophysical properties that modulate various signaling events. Dysregulation of these highly dynamic membrane domains can promote oncogenic signaling. Recently, it has been demonstrated that select membrane-targeted dietary bioactives (MTDBs) have the ability to remodel plasma membrane domains and subsequently reduce cancer risk. In this review, we focus on the importance of plasma membrane domain structural and signaling functionalities as well as how loss of membrane homeostasis can drive aberrant signaling. Additionally, we discuss the intricacies associated with the investigation of these membrane domain features and their associations with cancer biology. Lastly, we describe the current literature focusing on MTDBs, including mechanisms of chemoprevention and therapeutics in order to establish a functional link between these membrane-altering biomolecules, tuning of plasma membrane hierarchal organization, and their implications in cancer prevention.

Omega-3 polyunsaturated fatty acids as adjuvant therapy of colorectal cancer

The majority of evidence linking anti-colorectal cancer (CRC) activity with omega-3 polyunsaturated fatty acids (O3FAs) has focussed on decreased CRC risk (prevention). More recently, preclinical data and human observational studies have begun to make the case for adjuvant treatment of advanced CRC. Herein, we review latest data regarding the effect of O3FAs on post-diagnosis CRC outcomes, including mechanistic preclinical data, evidence that O3FAs have beneficial effects on efficacy and tolerability of CRC chemotherapy, and human epidemiological data linking dietary O3FA intake with CRC outcomes. We also highlight ongoing randomised controlled trials of O3FAs with CRC endpoints and discuss critical gaps in the evidence base, which include limited understanding of the effects of O3FAs on the tumour microenvironment, the host immune response to CRC, and the intestinal microbiome.

Metabolism-Based Therapeutic Strategies Targeting Cancer Stem Cells

Cancer heterogeneity constitutes the major source of disease progression and therapy failure. Tumors comprise functionally diverse subpopulations, with cancer stem cells (CSCs) as the source of this heterogeneity. Since these cells bear in vivo tumorigenicity and metastatic potential, survive chemotherapy and drive relapse, its elimination may be the only way to achieve long-term survival in patients. Thanks to the great advances in the field over the last few years, we know now that cellular metabolism and stemness are highly intertwined in normal development and cancer. Indeed, CSCs show distinct metabolic features as compared with their more differentiated progenies, though their dominant metabolic phenotype varies across tumor entities, patients and even subclones within a tumor. Following initial works focused on glucose metabolism, current studies have unveiled particularities of CSC metabolism in terms of redox state, lipid metabolism and use of alternative fuels, such as amino acids or ketone bodies. In this review, we describe the different metabolic phenotypes attributed to CSCs with special focus on metabolism-based therapeutic strategies tested in preclinical and clinical settings.

Omega-3 fatty acids, membrane remodeling and cancer prevention

Proteins are often credited as the macromolecule responsible for performing critical cellular functions, however lipids have recently garnered more attention as our understanding of their role in cell function and human health becomes more apparent. Although cellular membranes are the lipid environment in which many proteins function, it is now apparent that protein and lipid assemblies can be organized to form distinct micro- or nanodomains that facilitate signaling events. Indeed, it is now appreciated that cellular function is partly regulated by the specific spatiotemporal lipid composition of the membrane, down to the nanosecond and nanometer scale. Furthermore, membrane composition is altered during human disease processes such as cancer and obesity. For example, an increased rate of lipid/cholesterol synthesis in cancerous tissues has long been recognized as an important aspect of the rewired metabolism of transformed cells. However, the contribution of lipids/cholesterol to cellular function in disease models is not yet fully understood. Furthermore, an important consideration in regard to human health is that diet is a major modulator of cell membrane composition. This can occur directly through incorporation of membrane substrates, such as fatty acids, e.g., n-3 polyunsaturated fatty acids (n-3 PUFA) and cholesterol. In this review, we describe scenarios in which changes in membrane composition impact human health. Particular focus is placed on the importance of intrinsic lipid/cholesterol biosynthesis and metabolism and extrinsic dietary modification in cancer and its effect on plasma membrane properties.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Nutritional Interventions in the Patient with Inflammatory Bowel Disease

Nutritional strategies have been explored as primary or adjunct therapies for inflammatory bowel disease (IBD). Exclusive enteral nutrition is effective for the induction of remission in Crohn disease and is recommended as a first-line therapy for children. Dietary strategies focus on adjusting the ratio of consumed nutrients that are proinflammatory or antiinflammatory. Treatments with dietary supplements focus on the antiinflammatory effects of the individual supplements (eg, curcumin, omega-3 fatty acids, vitamin D) or their positive effects on the intestinal microbiome (eg, prebiotics, probiotics). This article discusses the role of diets and dietary supplements in the treatment of IBD.

Effects of Omegaven®, EPA, DHA and oxaliplatin on oesophageal adenocarcinoma cell lines growth, cytokine and cell signal biomarkers expression

Background

There is limited evidence assessing the effects of omega-3 polyunsaturated fatty acids (PUFAs) on oesophageal adenocarcinoma, both in vitro and in vivo. We evaluated the effects of the omega-3 PUFA and oxaliplatin on OE33 and OE19 cells.

Method

The two oesophageal cells were treated with Omegaven® (fish oil emulsion), EPA, DHA and oxaliplatin and incubated for up to 144 h.

Results

The following inhibitory effects were observed on OE33 cells: EPA reduced cell growth by 39% (p = 0.001), DHA by 59% (p < 0.000) and Oxaliplatin by 77% (p < 0.000). For OE19 cells, the EPA reduced growth by 1% (p = 0.992), DHA by 26% (p = 0.019) and oxaliplatin by 76% (p < 0.000). For both cells, Omegaven® resulted in reduced cell growth at intermediate concentrations (20-40 μM) and increased cell growth at low (10 μM) and high (50 μM) concentrations. DHA, Omegaven® and oxaliplatin were associated with significant downregulation of VEGF and p53 protein, and upregulation of p21 protein. DHA, Omegaven® and Oxaliplatin also led to significant downregulation of the total ERK1/2 and Akt proteins.

Conclusion

DHA, Omegaven® and oxaliplatin were associated with downregulation of p53 and VEGF in both cells. Of the PUFAs studied, DHA alone or in combination (Omegaven®) had greater in vitro anti-cancer effects than EPA alone.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0664-1) contains supplementary material, which is available to authorized users.

Dietary fatty acids modulation of human colon cancer cells: mechanisms and future perspectives

Colorectal cancer (CRC) is one of the most common malignancies worldwide and its pathogenesis is proven to be related with dietary patterns, namely dietary fatty acid (FA) intake. We reviewed the evidences regarding the effect of different dietary FAs on human CRC cell lines proliferation and apoptosis. Altogether, the results obtained from in vitro studies show that monounsaturated FAs lack evidence regarding both proliferation and apoptosis, whereas there is a consensus about the anti-proliferative and pro-apoptotic effects, involving different intracellular targets, of n-3 polyunsaturated FAs, while n-6 series show a similar effect or no effects. The response to these dietary components depends on the cell type as well as the amount and duration of exposure. These results highlight the importance of identifying molecular targets for dietary components aiming to interfere with one of the main risk factors related with CRC incidence and prevalence.

Emerging role of chemoprotective agents in the dynamic shaping of plasma membrane organization

In the context of an organism, epithelial cells by nature are designed to be the defining barrier between self and the outside world. This is especially true for the epithelial cells that form the lining of the digestive tract, which absorb nutrients and serve as a barrier against harmful substances. These cells are constantly bathed by a complex mixture of endogenous (bile acids, mucus, microbial metabolites) and exogenous (food, nutrients, drugs) bioactive compounds. From a cell biology perspective, this type of exposure would directly impact the plasma membrane, which consists of a myriad of complex lipids and proteins. The plasma membrane not only functions as a barrier but also as the medium in which cellular signaling complexes form and function. This property is mediated by the organization of the plasma membrane, which is exquisitely temporally (nanoseconds to minutes) and spatially (nanometers to micrometers) regulated. Since numerous bioactive compounds found in the intestinal lumen can directly interact with lipid membranes, we hypothesize that the dynamic reshaping of plasma membrane organization underlies the chemoprotective effect of select membrane targeted dietary bioactives (MTDBs). This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Chemopreventive and Chemotherapeutic Effects of Fish Oil derived Omega-3 Polyunsaturated Fatty Acids on Colon Carcinogenesis

Colorectal cancer is the third most common cause of cancer related death in the world. Multiple lines of evidence suggest that there is an association between consumption of dietary fat and colon cancer risk. Not only the amount but also the type and the ratio of fatty acids comprising dietary fats consumed have been implicated in the etiology and pathogenesis of colon cancer. Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been known to inhibit development of colon cancer by downregulating the expression of genes involved in colon carcinogenesis and also by altering the membrane lipid composition. Data from laboratory, epidemiological, and clinical studies substantiate the beneficial role of n-3 PUFAs in preventing colitis and subsequent development of colon cancer. In addition, recent studies suggest that some n-3 PUFAs can be effective as an adjuvant with chemotherapeutic agents and other natural anticancer compounds in the management of colon cancer. In this review, we discuss chemopreventive and therapeutic effects of fish oil derived long chain n-3 PUFAs, particularly EPA and DHA, with focus on synergetic effects of which they exert when combined with chemotherapeutic agents and other natural compounds.

Effects of omega-3 fatty acids on patients undergoing surgery for gastrointestinal malignancy: a systematic review and meta-analysis

Background

Surgical resection remains the primary treatment for gastrointestinal (GI) malignancy including early-stage cancer. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to have beneficial clinical and immune-modulating effects in the prognosis of GI cancer patients undergoing surgery.

Methods

We searched PubMed, Embase, EBSCO-Medline, Cochrane Central Register of Controlled Trials (CENTRAL), CNKI and Wanfang to identify primary research reporting the effects of n-3 PUFAs compared with isocaloric nutrition on GI cancer patients who underwent surgery up to the end of June 30, 2016. Two authors independently reviewed and selected eligible randomized controlled trials (RCTs).

Results

A total of 9 RCTs (623 participants) were included. The n-3 PUFAs regime resulted in lower levels of C-reactive protein (CRP) (P < 0.05), interleukin-6 (IL-6) (P < 0.01), and higher levels of albumin (ALB), CD3⁺ T cells, CD4⁺ T cells and CD4⁺/CD8⁺ ratio (P < 0.05) compared with the isocaloric nutrition regime. However, there was no significant difference in the level of tumor necrosis factor-α (TNF-α) between the n-3 PUFAs regime and the isocaloric nutrition regime (P = 0.17). And the level of CD8 ⁺ T cells decreased compared with the isocaloric nutrition regime (P < 0.0001).

Conclusions

Our meta-analysis revealed that n-3 PUFAs are effective in improving the nutritional status and immune function of GI cancer patients undergoing surgery as they effectively enhance immunity and attenuate the inflammatory response.

Polyunsaturated Fatty Acids and Their Derivatives: Therapeutic Value for Inflammatory, Functional Gastrointestinal Disorders, and Colorectal Cancer

Polyunsaturated fatty acids (PUFAs) are bioactive lipids which modulate inflammation and immunity. They gained recognition in nutritional therapy and are recommended dietary supplements. There is a growing body of evidence suggesting the usefulness of PUFAs in active therapy of various gastrointestinal (GI) diseases. In this review we briefly cover the systematics of PUFAs and their metabolites, and elaborate on their possible use in inflammatory bowel disease (IBD), functional gastrointestinal disorders (FGIDs) with focus on irritable bowel syndrome (IBS), and colorectal cancer (CRC). Each section describes the latest findings from in vitro and in vivo studies, with reports of clinical interventions when available.

Original Research: Effect of various dietary fats on fatty acid profile in duck liver: Efficient conversion of short-chain to long-chain omega-3 fatty acids

Omega-3 fatty acids, especially long-chain omega-3 fatty acids, have been associated with potential health benefits for chronic disease prevention. Our previous studies found that dietary omega-3 fatty acids could accumulate in the meat and eggs in a duck model. This study was to reveal the effects of various dietary fats on fatty acid profile and conversion of omega-3 fatty acids in duck liver. Female Shan Partridge Ducks were randomly assigned to five dietary treatments, each consisting of 6 replicates of 30 birds. The experimental diets substituted the basal diet by 2% of flaxseed oil, rapeseed oil, beef tallow, or fish oil, respectively. In addition, a dose response study was further conducted for flaxseed and fish oil diets at 0.5%, 1%, and 2%, respectively. At the end of the five-week treatment, fatty acids were extracted from the liver samples and analyzed by GC-FID. As expected, the total omega-3 fatty acids and the ratio of total omega-3/omega-6 significantly increased in both flaxseed and fish oil groups when compared with the control diet. No significant change of total saturated fatty acids or omega-3 fatty acids was found in both rapeseed and beef tallow groups. The dose response study further indicated that 59-81% of the short-chain omega-3 ALA in flaxseed oil-fed group was efficiently converted to long-chain DHA in the duck liver, whereas 1% of dietary flaxseed oil could produce an equivalent level of DHA as 0.5% of dietary fish oil. The more omega-3 fatty acids, the less omega-6 fatty acids in the duck liver. Taken together, this study showed the fatty acid profiling in the duck liver after various dietary fat consumption, provided insight into a dose response change of omega-3 fatty acids, indicated an efficient conversion of short- to long-chain omega-3 fatty acid, and suggested alternative long-chain omega-3 fatty acid-enriched duck products for human health benefits.

Omega-3 polyunsaturated fatty acids and cancer: lessons learned from clinical trials

Over the past decades, extensive studies have addressed the therapeutic effects of omega-3 polyunsaturated fatty acids (omega-3 FAs) against different human diseases such as cardiovascular and neurodegenerative diseases, cancer, etc. A growing body of scientific research shows the pharmacokinetic information and safety of these natural occurring substances. Moreover, during recent years, a plethora of studies has demonstrated that omega-3 FAs possess therapeutic role against certain types of cancer. It is also known that omega-3 FAs can improve efficacy and tolerability of chemotherapy. Previous reports showed 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 antineoplastic effect of omega-3 FAs. In this review, we have collected the available clinical data on the therapeutic role of omega-3 FAs against breast cancer, colorectal cancer, leukemia, gastric cancer, pancreatic cancer, esophageal cancer, prostate cancer, lung cancer, head and neck cancer, as well as cancer cachexia. We also discussed the chemistry, dietary source, and bioavailability of omega-3 FAs, and the potential molecular mechanisms of anticancer and adverse effects.

Targeting cancer stem-like cells using dietary-derived agents - Where are we now?

Diet has been linked to an overwhelming proportion of cancers. Current chemotherapy and targeted therapies are limited by toxicity and the development of resistance against these treatments results in cancer recurrence or progression. In vitro evidence indicates that a number of dietary-derived agents have activity against a highly tumorigenic, chemoradiotherapy resistant population of cells within a tumour. This population is associated with cancer recurrence and is therefore clinically significant. Targeting this subpopulation, termed cancer stem-like cells with dietary-derived agents provides a potentially low toxicity strategy to enhance current treatment regimens. In addition, dietary-derived compounds also provide a novel approach to cancer prevention strategies. This review focusses on selected diet-derived agents that have been shown to specifically target cancer stem-like cells using in vivo models, or in clinical trials. Furthermore, the potential limitations of these studies are discussed, and areas of research that need to be addressed to allow successful translation of dietary-derived agents to the clinical arena are highlighted.

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.

Omega-3 Fatty Acids and Cancer Cell Cytotoxicity: Implications for Multi-Targeted Cancer Therapy

Cancer is a major disease worldwide. Despite progress in cancer therapy, conventional cytotoxic therapies lead to unsatisfactory long-term survival, mainly related to development of drug resistance by tumor cells and toxicity towards normal cells. n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can exert anti-neoplastic activity by inducing apoptotic cell death in human cancer cells either alone or in combination with conventional therapies. Indeed, n-3 PUFAs potentially increase the sensitivity of tumor cells to conventional therapies, possibly improving their efficacy especially against cancers resistant to treatment. Moreover, in contrast to traditional therapies, n-3 PUFAs appear to cause selective cytotoxicity towards cancer cells with little or no toxicity on normal cells. This review focuses on studies investigating the cytotoxic activity of n-3 PUFAs against cancer cells via apoptosis, analyzing the molecular mechanisms underlying this effective and selective activity. Here, we highlight the multiple molecules potentially targeted by n-3 PUFAs to trigger cancer cell apoptosis. This analysis can allow a better comprehension of the potential cytotoxic therapeutic role of n-3 PUFAs against cancer, providing specific information and support to design future pre-clinical and clinical studies for a better use of n-3 PUFAs in cancer therapy, mainly combinational therapy.

Omega-3 Polyunsaturated Fatty Acids: The Way Forward in Times of Mixed Evidence

Almost forty years ago, it was first hypothesized that an increased dietary intake of omega-3 polyunsaturated fatty acids (PUFA) from fish fat could exert protective effects against several pathologies. Decades of intense preclinical investigation have supported this hypothesis in a variety of model systems. Several clinical cardiovascular studies demonstrated the beneficial health effects of omega-3 PUFA, leading medical institutions worldwide to publish recommendations for their increased intake. However, particularly in recent years, contradictory results have been obtained in human studies focusing on cardiovascular disease and the clinical evidence in other diseases, particularly chronic inflammatory and neoplastic diseases, was never established to a degree that led to clear approval of treatment with omega-3 PUFA. Recent data not in line with the previous findings have sparked a debate on the health efficacy of omega-3 PUFA and the usefulness of increasing their intake for the prevention of a number of pathologies. In this review, we aim to examine the controversies on the possible use of these fatty acids as preventive/curative tools against the development of cardiovascular, metabolic, and inflammatory diseases, as well as several kinds of cancer.