Growth inhibitory effect of polyunsaturated fatty acids (PUFAs) on colon cancer cells via their growth inhibitory metabolites and fatty acid composition changes

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.

Targeting PTGES/PGE2 axis enhances sensitivity of colorectal cancer cells to 5-fluorouracil

Insensitivity and resistance to 5-fluorouracil (5FU) remain as major hurdles for effective and durable 5FU-based chemotherapy in colorectal cancer (CRC) patients. In this study, we identified prostaglandin E synthase (PTGES)/prostaglandin E2 (PGE2) axis as an important regulator for 5FU sensitivity in CRC cells. We found that PTGES expression and PGE2 production are elevated in CRC cells in comparison to normal colorectal epithelial cells. Depletion of PTGES significantly enhanced the inhibitory effect of 5FU on CRC cell viability that was fully reverted by exogenous supplement of PGE2. Inhibition of PTGES enzymatic function, by either inducing loss-of-function mutant or treatment with selective inhibitors, phenocopied the PTGES depletion in terms of 5FU sensitization. Mechanistically, PTGES/PGE2 axis modulates glycolysis in CRC cells, thereby regulating the 5FU sensitivity. Importantly, high PTGES expression is correlated with poor prognosis in 5FU-treated CRC patients. Thus, our study defines PTGES/PGE2 axis as a novel therapeutic target for enhancing the efficacy of 5FU-based chemotherapy in CRC.

Free Fatty Acids from Type 2 Diabetes Mellitus Serum Remodel Mesenchymal Stem Cell Lipids, Hindering Differentiation into Primordial Germ Cells

Type 2 diabetes mellitus (T2DM) adversely affects the essential characteristics of adipose tissue-derived mesenchymal stem cells (AdMSCs). Given that T2DM is associated with an altered serum free fatty acid (FFA) profile, we examined whether diabetic serum FFAs influence the viability, differentiation, and fatty acid composition of the major lipid fractions of human AdMSCs in vitro. Serum FFAs were isolated from 7 diabetic and 10 healthy nondiabetic female individuals. AdMSCs were cultured and differentiated into primordial germ cell-like cells (PGCLCs) in the presence of either diabetic or nondiabetic FFAs. Cell viability was assessed using trypan blue staining. Cell differentiation was evaluated by measuring the PGCLC transcriptional markers Blimp1 and Stella. Lipid fractionation and fatty acid quantification were performed using thin-layer chromatography and gas-liquid chromatography, respectively. Both diabetic and nondiabetic FFAs significantly reduced the viability of PGCLCs. The gene expression of both differentiation markers was significantly lower in cells exposed to diabetic FFAs than in those treated with nondiabetic FFAs. Saturated fatty acids were significantly increased and linoleic acid was significantly decreased in the cellular phospholipid fraction after exposure to diabetic FFAs. In contrast, monounsaturated fatty acids were reduced and linoleic acid was elevated in the cellular triglyceride fraction in response to diabetic FFAs. Such an altered serum FFA profile in patients with T2DM reduces the proliferation and differentiation potential of AdMSCs, presumably due to the aberrant distribution of fatty acids into cell phospholipids and triglycerides.

Dietary Intervention for Preventing Colorectal Cancer: A Practical Guide for Physicians

Colorectal cancer (CRC) is a disease with high prevalence and mortality. Estimated preventability for CRC is approximately 50%, indicating that altering modifiable factors, including diet and body weight, can reduce CRC risk. There is strong evidence that dietary factors including whole grains, high-fiber, red and processed meat, and alcohol can affect the risk of CRC. An alternative strategy for preventing CRC is use of a chemopreventive supplement that provides higher individual exposure to nutrients than what can be obtained from the diet. These include calcium, vitamin D, folate, n-3 polyunsaturated fatty acids, and phytochemicals. Several intervention trials have shown that these dietary chemopreventives have positive protective effects on development and progression CRC. Research on chemoprevention with phytochemicals that possess anti-inflammatory and/or, anti-oxidative properties is still in the preclinical phase. Intentional weight loss by bariatric surgery has not been effective in decreasing long-term CRC risk. Physicians should perform dietary education for patients who are at high risk of cancer for changing their dietary habits and behaviour. An increased understanding of the role of individual nutrients linked to the intestinal micro-environment and stages of carcinogenesis would facilitate the development of the best nutritional formulations for preventing CRC.

Anti-colorectal cancer effects of seaweed-derived bioactive compounds

Seaweeds are classified as Chlorophyta, Rhodophyta, and Phaeophyta. They constitute a number of the most significant repositories of new therapeutic compounds for human use. Seaweed has been proven to possess diverse bioactive properties, which include anticancer properties. The present review focuses on colorectal cancer, which is a primary cause of cancer-related mortality in humans. In addition, it discusses various compounds derived from a series of seaweeds that have been shown to eradicate or slow the progression of cancer. Therapeutic compounds extracted from seaweed have shown activity against colorectal cancer. Furthermore, the mechanisms through which these compounds can induce apoptosis in vitro and in vivo were reviewed. This review emphasizes the potential utility of seaweeds as anticancer agents through the consideration of the capability of compounds present in seaweeds to fight against colorectal cancer.

The probiotic Lactobacillus rhamnosus GG (LGG) restrains the angiogenic potential of colorectal carcinoma cells by activating a pro-resolving program via formyl peptide receptor 1

Formyl peptide receptors (FPR1, FPR2 and FPR3) are innate immune sensors of pathogen and commensal bacteria and have a role in colonic mucosa homeostasis. We identified FPR1 as a tumour suppressor in gastric cancer cells due to its ability to sustain an inflammation resolution response with antiangiogenic potential. Here, we investigate whether FPR1 exerts similar functions in colorectal carcinoma (CRC) cells. Since it has been shown that the commensal bacterium Lactobacillus rhamnosus GG (LGG) can promote intestinal epithelial homeostasis through FPR1, we explored the possibility that it could induce proresolving and antiangiogenic effects in CRC cells. We demonstrated that pharmacologic inhibition or genetic deletion of FPR1 in CRC cells caused a reduction of proresolving mediators and a consequent upregulation of angiogenic factors. The activation of FPR1 mediates opposite effects. Proresolving, antiangiogenic and homeostatic functions were also observed upon treatment of CRC cells with supernatant of LGG culture, but not of other lactic acid or nonprobiotic bacteria (i.e. Bifidobacterium bifidum or Escherichia coli). These activities of LGG are dependent on FPR1 expression and on the subsequent MAPK signalling activation. Thus, the innate immune receptor FPR1 could be a regulator of the balance between microbiota, inflammation and cancer in CRC models.

Biochemical and Metabolical Pathways Associated with Microbiota-Derived Butyrate in Colorectal Cancer and Omega-3 Fatty Acids Implications: A Narrative Review

Knowledge regarding the influence of the microbial community in cancer promotion or protection has expanded even more through the study of bacterial metabolic products and how they can modulate cancer risk, which represents an extremely challenging approach for the relationship between intestinal microbiota and colorectal cancer (CRC). This review discusses research progress on the effect of bacterial dysbiosis from a metabolic point of view, particularly on the biochemical mechanisms of butyrate, one of the main short chain fatty acids (SCFAs) with anti-inflammatory and anti-tumor properties in CRC. Increased daily intake of omega-3 polyunsaturated fatty acids (PUFAs) significantly increases the density of bacteria that are known to produce butyrate. Omega-3 PUFAs have been proposed as a treatment to prevent gut microbiota dysregulation and lower the risk or progression of CRC.

Krill oil supplementation reduces the growth of CT-26 orthotopic tumours in Balb/c mice

Background

We have previously reported that the free fatty acid extract (FFAE) of krill oil (KO) significantly inhibits the proliferation and migration, and induces apoptosis of colorectal cancer (CRC) cells. This study aimed to investigate the in vivo efficacy of various doses of KO supplementation on the inhibition of CRC tumour growth, molecular markers of proliferation, angiogenesis, apoptosis, the epidermal growth factor receptor (EGFR) and its downstream molecular signalling.

Methods

Male Balb/c mice were randomly divided into four groups with five in each group. The control (untreated) group received standard chow diet; and other three groups received KO supplementation at 5%, 10%, and 15% of their daily dietary intake respectively for three weeks before and after the orthotopic implantation of CT-26 CRC cells in their caecum. The expression of cell proliferation marker Ki-67 and angiogenesis marker CD-31 were assessed by immunohistochemistry. The expression of EGFR, phosphorylated EGFR (pEGFR), protein kinase B (AKT), pAKT, extracellular signal-regulated kinase (ERK1/2), pERK1/2, cleaved caspase-7, cleaved poly (ADP-ribose) polymerase (PARP), and DNA/RNA damage were determined by western blot.

Results

KO supplementation reduced the CRC tumour growth in a dose-dependent manner; with 15% of KO being the most effective in reduction of tumour weight and volume (68.5% and 68.3% respectively, P < 0.001), inhibition of cell proliferation by 69.9% (P < 0.001) and microvessel density by 72.7% (P < 0.001). The suppressive effects of KO on EGFR and its downstream signalling, ERK1/2 and AKT, were consistent with our previous in vitro observations. Furthermore, KO exhibited pro-apoptotic effects on tumour cells as indicated by an increase in the expression of cleaved PARP by 3.9-fold and caspase-7 by 8.9-fold.

Conclusions

This study has demonstrated that KO supplementation reduces CRC tumour growth by inhibiting cancer cell proliferation and blood vessel formation and inducing apoptosis of tumour cells. These anti-cancer effects are associated with the downregulation of the EGFR signalling pathway and activation of caspase-7, PARP cleavage, and DNA/RNA damage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03521-4.

Bioactive Compounds of Raspberry Oil Emulsions Induced Oxidative Stress via Stimulating the Accumulation of Reactive Oxygen Species and NO in Cancer Cells

There are growing interests in the complex combinations of natural compounds that may advance the therapy of cancer. Such combinations already exist in foods, and a good representative is seed oils. Two raspberry oils: cold pressed (ROCOP) and one extracted by supercritical CO₂ (ROSCO2) were evaluated for their chemical characteristics and oil emulsions for cell suppression potential against colon adenocarcinoma (LoVo), doxorubicin-resistant colon adenocarcinoma (LoVo/DX), breast cancer (MCF7), doxorubicin-resistant breast cancer (MCF7/DX), and lung cancer (A549) cell lines. The cytotoxicity was also assessed on normal human dermal fibroblasts (NHDFs). With increasing concentration of raspberry oil emulsions (0.5–10%), increasing inhibition of cancer cell viability and proliferation in all of the lines was observed, with different degrees of potency between cancer types and oil tested. ROSCO2 strongly induced free radical production and DNA strand damage in LoVo and MCF7 cells especially doxorubicin-resistant lines. This suggests that ROSCO2 engages and effectively targets the vulnerabilities of the cancer cell. Generally, both ROSCO2 and ROCOP could be a nontoxic support in therapy of selected human cancers.

Krill oil extract inhibits the migration of human colorectal cancer cells and down-regulates EGFR signalling and PD-L1 expression

BACKGROUND

The currently available treatments for colorectal cancer (CRC) are often associated with serious side-effects. Therefore, the development of a novel nutraceutical agent may provide an alternative complementary therapy for CRC. Overexpression of the epidermal growth factor receptor (EGFR) associates with a range of cancers while downregulation of EGFR signalling can inhibit cancer growth. Our previous studies have shown that the free fatty acid extract (FFAE) of krill oil exhibits anti-proliferative and pro-apoptotic properties. This study determines the effects of krill oil extract on the migration of human CRC cells, and its potential role in modulating EGFR signalling pathway and the expression of programmed death ligand 1 (PD-L1).

METHODS

Human CRC cells, DLD-1 and HT-29 were treated with FFAE of KO at 0.03 and 0.12 μL/100 μL for 8 or 24 h. Cell migration was determined by Boyden chamber migration assay. The expression of EGFR, phosphorylated EGFR (pEGFR), protein kinase B (AKT), phosphorylated AKT (pAKT), extracellular signal regulated kinase (ERK1/2), phosphorylated ERK1/2 (pERK1/2) as well as PD-L1 were assessed by western blotting and immunohistochemistry.

RESULTS

The FFAE of krill oil significantly inhibited cell migration compared to ethanol-treated (vehicle control) cells (P < 0.01 to P < 0.001). At the molecular level, krill oil extract reduced the expression of EGFR, pEGFR (P < 0.001 for both) and their downstream signalling, pERK1/2 and pAKT (P < 0.01 to P < 0.001) without altering total ERK 1/2 and AKT levels. In addition, the expression of PD-L1 was reduced by 67 to 72% (P < 0.001) following the treatment with krill oil extract.

CONCLUSION

This study has demonstrated that krill oil may be a potential therapeutic/adjunctive agent for CRC attributed to its anti-migratory effects.. The potential anti-cancer properties of krill oil are likely to be associated with the downregulation of EGFR, pEGFR and their downstream pERK/ERK1/2 and pAKT/AKT signalling pathways along with the downregulation of PD-L1.

The Role of Pro-Resolving Lipid Mediators in Colorectal Cancer-Associated Inflammation: Implications for Therapeutic Strategies

Inflammation is a recognized hallmark of cancer that contributes to the development and progression of colorectal cancer (CRC). Anti-inflammatory drugs currently used for the treatment of CRC show many adverse side effects that prompted researchers to propose the polyunsaturated fatty acids-derived specialized pro-resolving mediators (SPMs) as promoters of resolution of cancer-associated inflammation. SPMs were found to inhibit the CRC-associated pro-inflammatory milieu via specific G-coupled protein receptors, although clinical data are still lacking. This review aims to summarize the state-of-the-art in this field, ultimately providing insights for the development of innovative anti-CRC therapies that promote the endogenous lipid-mediated resolution of CRC-associated inflammation.

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.

Marine Oomycetes (Halophytophthora and Salispina): A Potential Source of Fatty Acids with Cytotoxic Activity Against Breast Adenocarcinoma Cells (MCF7)

Marine oomycetes are ubiquitous, fungus-like eukaryotes known to produce fatty acids with potential anticancer activity. The long chain omega-3 and omega-6 fatty acids are currently popular and considered as safe when used as nutraceuticals in cancer treatment. In this study, crude fatty acids from three marine oomycetes, Halophytophthora spp. (T12GP1 and T12YBP2) and Salispina hoi (USTCMS 1611), were explored for their cytotoxic and apoptotic potentials against human breast adenocarcinoma cells (MCF7) and normal human dermal fibroblasts (HDFn). Extracts from mycelia mats consisted of diverse saturated, monounsaturated, and polyunsaturated fatty acids such as linoleic, α-linolenic, γ-linolenic, eicosatrienoic and eicosapentaenoic acids. The crude fatty acids from all three oomycetes in in vitro assays for cytotoxicity showed no toxicity (30% toxicity values) on HDFn cells. On MCF7 cells, however, IC₅₀ values of 23.44, 15.63, and 26.15 µg/mL were obtained with extracts from Halophytophthora T12GP1 and T12YBP2 and S. hoi, respectively. Treated MCF7 cells exhibited deformed cell membrane in MTT assay and also aggregation of DNA and disruption of nuclear membrane aggregation in nuclear staining; further, green signals indicative of apoptosis was recorded in caspase 3/7 assay.

Krill oil extract suppresses the proliferation of colorectal cancer cells through activation of caspase 3/9

Background

Currently available treatments for colorectal cancer (CRC) associate with numerous side-effects that reduce patients' quality of life. The effective nutraceuticals with high anti-proliferative efficacy and low side-effects are desirable. Our previous study has reported that free fatty acids extract (FFAE) of krill oil induced apoptosis of CRC cells, possibly associated with changes in mitochondrial membrane potential (MMP). The aims of this study were to compare the anti-proliferative efficacy of FFAE from krill oil on CRC cells with commonly used chemotherapeutic drug, Oxaliplatin, and to investigate the molecular mechanisms underlying the anti-proliferative effects of krill oil with a focus on intrinsic mitochondrial death pathway.

Methods

Three human CRC cell lines, including DLD-1, HT-29 and LIM-2405, and one mouse CRC cell line, CT-26, were treated with FFAE of KO and the bioactive components of krill oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 24 h and 48 h. Similarly, these cell lines were treated with Oxaliplatin, a commonly used drug for CRC treatment, for 24 h. The effects of FFAE of KO, EPA, DHA and Oxaliplatin on cell proliferation, mitochondrial membrane potential and reactive oxygen species (ROS) were determined via WST-1, JC-10, and ROS assays respectively. The expression of caspase-3, caspase-9 and DNA damage following treatments of FFAE of KO was investigated via western blotting and immunohistochemistry.

Results

The FFAE of KO, EPA and DHA significantly inhibited cell proliferation and increased formation of ROS in all four cell lines (P < 0.01). A small dose of FFAE from KO ranged from 0.06 μL/100 μL to 0.12 μL/100 μL containing low concentrations of EPA (0.13-0.52 μM) and DHA (0.06-0.26 μM) achieved similar anti-proliferative effect as Oxaliplatin (P > 0.05). Treatments with the FFAE of KO, EPA and DHA (2:1 ratio) resulted in a significant increase in the mitochondrial membrane potential (P < 0.001). Furthermore, the expression of active forms of caspase-3 and caspase-9 was significantly increased following the treatment of FFAE of KO.

Conclusions

The present study has demonstrated that the anti-proliferative effects of krill oil on CRC cells are comparable with that of Oxaliplatin, and its anti-proliferative property is associated with the activation of caspase 3/9 in the CRC cells.

Methylselenol release as a cytotoxic tool: a study of the mechanism of the activity achieved by two series of methylselenocarbamate derivatives

A molecular modeling study has been carried out on two previously reported series of methylselenocarbamate derivatives that show remarkable antiproliferative and cytotoxic in vitro activity, against a panel of human cancer cell lines. These derivatives can be considered as having been constructed by a selenomethyl fragment located over a carbon atom which is decorated with two carbamate moieties, both aliphatic and aromatic, one of them attached by a single bond to the central carbon atom, while the second is connected by a double bond. According to the data obtained, these derivatives can undergo a water-mediated nucleophilic attack on the carbons with marked electrophilic character, which leads to the rupture of C-Se and carbamate C-O bonds. The aliphatic derivatives, series 1, show an early release of methylselenol and a further release of hydroxyl derivatives (alcohols), whereas the aromatic carbamates, series 2, show an early release of phenols followed by the subsequent release of methylselenol. Thus, the activity of the compounds can be related to the progressive release of active fragments. The data that support this connection are related to the overall molecular topology, volume and surface area as well as to quantum parameters such as the relative electrophilic character of the target carbon atoms (measured in terms of positive charge values) or the bond order values, especially concerning the central C-SeCH3 bond and the carbamate ones. Moreover, the data obtained regarding the chromatographic behavior of some representative compounds confirm this proposal.

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.

Antiproliferative Activity and Characterization of Metabolites of Aspergillus nidulans: An Endophytic Fungus from Nyctanthes arbor-tristis Linn. Against Three Human Cancer Cell Lines

BACKGROUND

Endophytic fungi are receiving attention as sources of structurally novel bioactive secondary metabolites towards drug discovery from natural products. This study reports the isolation and characterization of secondary metabolites from an endophytic fungus Aspergillus nidulans, associated with Nyctanthes arbor-tristis Linn., a plant which has a traditional use to cure many ailments including cancer.

OBJECTIVE

The objective of this study was to evaluate the antiproliferative activity of the metabolites of A. nidulans from N. arbor-tristis on three human cancer cell lines, lung (NCI-H460), breast (MCF-7) and uterine cervix (HeLa), and carry out their characterization.

METHODS

The extracts of the endophytic fungus cultured on potato dextrose agar were subjected to various chromatographic techniques. Structures of pure compounds were determined using spectroscopic techniques. The non-polar constituents were analyzed by GC-MS. Antiproliferative activity was determined by sulforhodamine B (SRB) assay.

RESULTS

The extracts and fractions showed moderate to good growth inhibition of the aforementioned human cancer cell lines. The broth extract was most potent (IC50 = 10 ± 3.1 μg/mL and LC50= 95 ± 3.9) against HeLa whereas petroleum ether insoluble fraction of mycelium was most active against NCI-H460 and MCF-7 (IC50 = 10 ± 2.1 µg/mL and 18 ± 3.1 µg/mL respectively). GC-MS led to identify 12 compounds in mycelium and 19 compounds in broth. Four pure compounds were isolated and characterized one compound 5, 10-dihydrophenazine-1-carboxylic acid (1) from broth and three 1-hydroxy-3-methylxanthone (2), ergosterol (3) and sterigmatocystin (4) from mycelium. 1 has not been reported earlier as a plant/fungal metabolite while 2-4 are new from this source. Sterigmatocystin exhibited growth inhibitory effect (IC50 = 50 ± 2.5 µM/mL) against only MCF-7 cell line whereas other compounds had IC50 > 100.

CONCLUSIONS

In this paper, the cytotoxicity of mycelium and broth constituents of endophytic fungus Aspergillus nidulans from Nyctanthes arbor-tristis is reported for the first time. The study shows that fungus Aspergillus nidulans from Nyctanthes arbor-tristis is capable of producing biologically active natural compounds and provides a scientific rationale for further chemical investigations of endophyte-producing natural products.

Emerging cellular functions of the lipid metabolizing enzyme 15-Lipoxygenase-1

The oxygenation of polyunsaturated fatty acids such as arachidonic and linoleic acid through lipoxygenases (LOXs) and cyclooxygenases (COXs) leads to the production of bioactive lipids that are important both in the induction of acute inflammation and its resolution. Amongst the several isoforms of LOX that are expressed in mammals, 15-LOX-1 was shown to be important both in the context of inflammation, being expressed in cells of the immune system, and in epithelial cells where the enzyme has been shown to crosstalk with a number of important signalling pathways. This review looks into the latest developments in understanding the role of 15-LOX-1 in different disease states with emphasis on the emerging role of the enzyme in the tumour microenvironment as well as a newly re-discovered form of cell death called ferroptosis. We also discuss future perspectives on the feasibility of use of this protein as a target for therapeutic interventions.

Proteomics Study Reveals That Docosahexaenoic and Arachidonic Acids Exert Different In Vitro Anticancer Activities in Colorectal Cancer Cells

Two polyunsaturated fatty acids, docosahexaenoic acid (DHA) and arachidonic acid (ARA), as well as derivatives, such as eicosanoids, regulate different activities, affecting transcription factors and, therefore, DNA transcription, being a critical step for the functioning of fatty-acid-derived signaling. This work has attempted to determine the in vitro anticancer activities of these molecules linked to the gene transcription regulation of HT-29 colorectal cancer cells. We applied the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test along with lactate dehydrogenase and caspase-3 assays; proteome changes were assessed by "sequential windowed acquisition of all theoretical mass spectra" quantitative proteomics, followed by pathway analysis, to determine the affected molecular mechanisms. In all assays, DHA inhibited cell proliferation of HT-29 cells to a higher extent than ARA and acted primarily by downregulating proteasome particles, while ARA presented a dramatic effect on all six DNA replication helicase particles. The results indicated that both DHA and ARA are potential chemopreventive agent candidates.

Saturated, mono- and polyunsaturated fatty acid intake and cancer risk: results from the French prospective cohort NutriNet-Santé

PURPOSE

Lipid intakes such as saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids have been widely studied regarding cardiovascular health, but their relevance to cancer is unclear. Inconsistent epidemiological results may be explained by varied mechanisms involving PUFAs and redox balance, inflammatory status and cell signalling, along with interactions with other dietary components such as antioxidants, dietary fibre and more generally fruits and vegetable intakes. Therefore, this study aimed to investigate the associations between lipid intakes and cancer risk, and their potential modulation by vitamin C, vitamin E, dietary fibre and fruit and vegetable intakes.

METHODS

This prospective study included 44,039 participants aged ≥ 45 years from the NutriNet-Santé cohort (2009-2017). Dietary data were collected using repeated 24 h-dietary records. Multivariable Cox models were performed to characterize associations.

RESULTS

SFA intake was associated with increased overall [n = 1722 cases, HR_Q5vsQ1 = 1.44 (1.10-1.87), p-trend = 0.008] and breast [n = 545 cases, HR_Q5vsQ1 = 1.98 (1.24-3.17), p-trend = 0.01] cancer risks. n-6 PUFA [HR_Q5vsQ1 = 0.56 (0.32-0.97), p-trend = 0.01] and MUFA (HR_Q5vsQ1 = 0.41 [0.18-0.0.95), p-trend = 0.009] intakes were associated with a decreased risk of digestive cancers (n = 190 cases). Associations between n-6 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intakes and digestive cancer risk were modulated by dietary fibre, vitamin C and fruit and vegetable intakes.

CONCLUSION

These findings suggested that SFA intake could increase overall and breast cancer risks while some unsaturated fatty acids could decrease digestive cancer risk. However, in line with mechanistic hypotheses, our results suggest that intakes of fruits and vegetables and their constituents (antioxidants, fibre) may interact with PUFAs to modulate these associations.

Mechanisms of Phytonutrient Modulation of Cyclooxygenase-2 (COX-2) and Inflammation Related to Cancer

The link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways. Cyclooxygenase-2 (COX-2), a key enzyme in fatty acid metabolism, is upregulated during both inflammation and cancer. COX-2 is induced by pro-inflammatory cytokines at the site of inflammation and enhanced COX-2-induced synthesis of prostaglandins stimulates cancer cell proliferation, promotes angiogenesis, inhibits apoptosis, and increases metastatic potential. As a result, COX-2 inhibitors are a subject of intense research interest toward potential clinical applications. Epidemiological studies highlight the potential benefits of diets rich in phytonutrients for cancer prevention. Plants contain numerous phytonutrient secondary metabolites shown to modulate COX-2. Studies have shown that these metabolites, some of which are used in traditional medicine, can reduce inflammation and carcinogenesis. This review describes the molecular mechanisms by which phytonutrients modulate inflammation, including studies of carotenoids, phenolic compounds, and fatty acids targeting various inflammation-related molecules and pathways associated with cancer. Examples of pathways include those of COX-2, mitogen-activated protein kinase kinase kinase, mitogen-activated protein kinase, pro-inflammatory cytokines, and transcription factors like nuclear factor kappa B. Such phytonutrient modulation of COX-2 and inflammation continue to be explored for applications in the prevention and treatment of cancer.

Composition and Concentration of Serum Fatty Acids of Phospholipids Depend on Tumour Location and Disease Progression in Colorectal Patients

BACKGROUND

Polyunsaturated fatty acids (PUFAs) play a role in the development/progression of colon cancer. The aim of the study was to assess the relation between serum phospholipids PUFAs, colorectal tumour localization and disease progression.

METHODS

A total of 67 patients (18 with proximal colon, 17 with distal colon and 32 with rectal tumour localization) as well as 16 controls were studied. One year after surgery, 33 patients had disease progression. Serum levels of C16:1(n-7), C18:1(n-9), C18:3(n-3), C20:5(n-3), C22:6(n- 3), C18:2(n-6), C20:2(n-6), C20:4(n-6) fatty acids of se - rum phospholipids were quantitatively measured before surgery by gas-chromatography.

RESULTS

Significantly higher mean value of C18:2, as compared to control, has been noted only for patients with proximal (p<0.05) and distal tumour (p<0.03) localization. The lower mean level of C20:5 and unsaturation index (UI) were observed in colorectal cancer patients regardless the tumour localization, but the statistical difference was noted only for patients with proximal tumours (p<0.05, p<0.03). In patients with proximal tumours, significantly lower mean level of C20:4 and UI were noted in patients with disease progression, as compared to patients with proximal tumours without disease progression (p<0.05).

CONCLUSION

The evaluation of PUFAs as a risk/prognostic factor in colorectal cancer patients should take into account tumour localization as a dependent variable.

Krill oil extract suppresses cell growth and induces apoptosis of human colorectal cancer cells

Background

Colorectal cancer (CRC) is the third most common cancer in the world. The current available treatments for CRC include surgery, chemotherapy and radiotherapy. However, surgery is only useful when the disease is diagnosed at the earlier stage. Chemotherapy and radiotherapy are associated with numerous side effects that decrease the patients’ quality of life. Safer, effective alternatives, such as natural compounds, to chemotherapy are desirable. This study assessed the efficacy of free fatty acid (FFA) extract of krill oil on three human CRC cells lines.

Methods

HCT-15, SW-480 and Caco-2 cells were treated with the FFA extracts of krill oil and fish oil for 48 h while treatments with the bioactive omega-3 polyunsaturated fatty acids (LC n-3 PUFA) of these marine oils, eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) in comparison with a n-6 PUFA, arachnoid acid (AA, C20:4n-6) were up to 72 h at the concentrations of 50, 100, 150 and 200 μM. Effects of all the treatments on cell proliferation were assessed using a water-soluble tetrazolium-1 (WST-1) assay kit at 24, 48 and 72 h. Effects of FFA extract of krill oil and EPA on apoptosis and mitochondrial membrane potential were determined using commercial kits after 48 h of treatment.

Results

Krill oil extract inhibited cell proliferation of all three cell lines in the similar manner as fish oil extract. A significant cell apoptosis and increase in mitochondrial membrane potential were observed after the treatment with krill oil extract. EPA at the concentration of 200 μM reduced significantly the proliferation of HCT-15 and SW-480 at 24, 48 and 72 h. In addition, EPA treatment (100 and 200 μM) resulted in significant cell apoptosis in all three cell lines. No significant changes were observed after treatment with DHA and AA.

Conclusions

Our results indicate that the FFA extract of krill oil maybe an effective chemotherapeutic agent to suppress proliferation and induce apoptosis in CRC cells through its bioactive constitute EPA. Although the exact mechanism of the pro-apoptotic properties of krill oil extract is unclear, mitochondrial pathway seems to be implicated.

Cancer Risk and Eicosanoid Production: Interaction between the Protective Effect of Long Chain Omega-3 Polyunsaturated Fatty Acid Intake and Genotype

Dietary inclusion of fish and fish supplements as a means to improve cancer prognosis and prevent tumour growth is largely controversial. Long chain omega-3 polyunsaturated fatty acids (LCn-3 PUFA), eicosapentaenoic acid and docosahexaenoic acid, may modulate the production of inflammatory eicosanoids, thereby influencing local inflammatory status, which is important in cancer development. Although in vitro studies have demonstrated inhibition of tumour cell growth and proliferation by LCn-3 PUFA, results from human studies have been mainly inconsistent. Genes involved in the desaturation of fatty acids, as well as the genes encoding enzymes responsible for eicosanoid production, are known to be implicated in tumour development. This review discusses the current evidence for an interaction between genetic polymorphisms and dietary LCn-3 PUFA in the risk for breast, prostate and colorectal cancers, in regards to inflammation and eicosanoid synthesis.

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.

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.