n-3 Polyunsaturated fatty acids induce acute myeloid leukemia cell death associated with mitochondrial glycolytic switch and Nrf2 pathway activation

The Impact of Polyunsaturated Fatty Acids in Cancer and Therapeutic Strategies

PURPOSE OF REVIEW

Cancer is a disease influenced by both genetic and environmental factors, with dietary lipids being a significant contributing factor. This review summarizes the role of polyunsaturated fatty acids (PUFAs) in the mechanism of tumor occurrence and development, and elucidate the role of PUFAs in tumor treatment.

RECENT FINDINGS

PUFAs exert their impact on cancer through altering lipid composition in cell membranes, interacting with cell membrane lipid receptors, directly modulating gene expression in the cell nucleus, and participating in the metabolism of lipid mediators. Most omega-3 PUFAs are believed to inhibit cell proliferation, promote cancer cell death, suppress cancer metastasis, alter energy metabolism, inhibit tumor microenvironment inflammation, and regulate immune responses involving macrophages, T cells, NK cells, and others. However, certain omega-6 PUFAs exhibit weaker anti-tumor effects and may even promote tumor development, such as by fostering inflammatory tumor microenvironment and enhancing tumor cell proliferation. PUFAs play important roles in hallmarks of cancer including tumor cell proliferation, cell death, migration and invasion, energy metabolism remodeling, epigenetics, and immunity. These findings provide insights into the mechanisms of cancer development and offers options for dietary management of cancer.

n-3 polyunsaturated fatty acids enhanced efficacy of cytarabine in iron-overloaded NALM-6 cells via apoptotic and oxidative pathways

Despite progress in treating acute lymphoblastic leukemia (ALL), the adverse effects of chemotherapy toxicity and iron overload from transfusions continue to affect patients' quality of life. Polyunsaturated fatty acids (PUFAs) exhibit both antitumor and anti-inflammatory properties in leukemia. This study investigated the influence of n-3 PUFA on the efficacy of cytarabine in cells with iron overload. Iron overload was induced in NALM-6 cells using ferric ammonium citrate (FAC) and quantified through atomic absorption spectroscopy (AAS). The impact of n-3 PUFA on NALM-6 cells' response to cytarabine was evaluated using MTT, lactate dehydrogenase (LDH), apoptosis, and cell cycle assays. Additionally, gene expression analyses were performed on apoptotic, anti-apoptotic, and inflammatory genes, along with oxidative stress markers such as reactive oxygen species (ROS) and malondialdehyde (MDA) levels. The administration of n-3 PUFA significantly enhanced the effectiveness of cytarabine in iron-overloaded NALM-6 cells, leading to increased LDH secretion, elevated apoptosis rates, and G1 phase cell cycle arrest. These effects were associated with the upregulation of apoptotic genes such as P53 and caspase-8, the downregulation of the anti-apoptotic gene Bcl2, and a decrease in the inflammatory gene TNF-α. Furthermore, there was a notable increase in ROS and MDA levels. Overall, n-3 PUFA treatment improved cytarabine's efficacy in iron-overloaded NALM-6 cells by activating apoptotic processes and oxidative stress pathways.

Optimization of concentrations of different n-3PUFAs on antioxidant capacity in mouse hepatocytes

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), mainly including α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), possess antioxidant properties and play a crucial role in growth and development. However, the combined effects of ALA, EPA, and DHA at different concentrations have rarely been reported. This work explored the effects of EPA, ALA, and DHA on the viability and antioxidant capacity of mouse hepatocytes, with the objective of enhancing the antioxidant capacity. Within the appropriate concentration range, cell viability and the activity of glutathione S-transferase, superoxide dismutase, and catalase were increased, while the oxidation products of malondialdehyde and the level of intracellular reactive oxygen species were obviously reduced. Thus, oxidative stress was relieved, and cellular antioxidant levels were improved. Finally, response surface optimization was carried out for EPA, ALA, and DHA, and the model was established. The antioxidant capacity of the cells was highest at EPA, ALA, and DHA concentrations of 145.46, 405.05, and 551.52 µM, respectively. These findings lay the foundation for further exploration of the interactive mechanisms of n-3 PUFAs in the body, as well as their applications in nutraceutical food.

Modulation of carcinogenesis with selected GRAS nutraceuticals via Keap1-Nrf2 signaling pathway

Keap1-Nrf2 is a fundamental signaling cascade known to promote or prevent carcinogenesis. Extensive studies identify the key target of modulatory aspects of Keap1-Nrf2 signaling against cancer. Nutraceuticals are those dietary agents with many health benefits that have immense potential for cancer chemoprevention. The nutritional supplements known as nutraceuticals are found to be one of the most promising chemoprevention agents. Upon investigating the dual nature of Nrf2, it became clear that, in addition to shielding normal cells from numerous stresses, Nrf2 may also promote the growth of tumors. In the present review, we performed a systematic analysis of the role of 12 different nutraceuticals like curcumin, sulforaphane, resveratrol, polyunsaturated fatty acids (PUFA) from fish oil, lycopene, soybean, kaempferol, allicin, thymoquinone, quercetin, gingerol, and piperine in modulating the Nrf2/Keap1 signaling mechanism. Among these, 12 Generally Recognized As Safe (GRAS) certified nutraceuticals, sulforaphane is the most extensively studied compound in modulating Keap1-Nrf signaling. Even though there is much evidence at preclinical levels, further high-quality research is still required to validate the potential role of these nutraceuticals in Keap1-Nrf2 modulation.

The Involvement of Polyunsaturated Fatty Acids in Apoptosis Mechanisms and Their Implications in Cancer

Cancer is a significant global public health issue and, despite advancements in detection and treatment, the prognosis remains poor. Cancer is a complex disease characterized by various hallmarks, including dysregulation in apoptotic cell death pathways. Apoptosis is a programmed cell death process that efficiently eliminates damaged cells. Several studies have indicated the involvement of polyunsaturated fatty acids (PUFAs) in apoptosis, including omega-3 PUFAs such as alpha-linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid. However, the role of omega-6 PUFAs, such as linoleic acid, gamma-linolenic acid, and arachidonic acid, in apoptosis is controversial, with some studies supporting their activation of apoptosis and others suggesting inhibition. These PUFAs are essential fatty acids, and Western populations today have a high consumption rate of omega-6 to omega-3 PUFAs. This review focuses on presenting the diverse molecular mechanisms evidence in both in vitro and in vivo models, to help clarify the controversial involvement of omega-3 and omega-6 PUFAs in apoptosis mechanisms in cancer.

Variation in Lipid Species Profiles among Leukemic Cells Significantly Impacts Their Sensitivity to the Drug Targeting of Lipid Metabolism and the Prognosis of AML Patients

Several studies have linked bad prognoses of acute myeloid leukemia (AML) to the ability of leukemic cells to reprogram their metabolism and, in particular, their lipid metabolism. In this context, we performed "in-depth" characterization of fatty acids (FAs) and lipid species in leukemic cell lines and in plasma from AML patients. We firstly showed that leukemic cell lines harbored significant differences in their lipid profiles at steady state, and that under nutrient stress, they developed common mechanisms of protection that led to variation in the same lipid species; this highlights that the remodeling of lipid species is a major and shared mechanism of adaptation to stress in leukemic cells. We also showed that sensitivity to etomoxir, which blocks fatty acid oxidation (FAO), was dependent on the initial lipid profile of cell lines, suggesting that only a particular "lipidic phenotype" is sensitive to the drug targeting of FAO. We then showed that the lipid profiles of plasma samples from AML patients were significantly correlated with the prognosis of patients. In particular, we highlighted the impact of phosphocholine and phosphatidyl-choline metabolism on patients' survival. In conclusion, our data show that balance between lipid species is a phenotypic marker of the diversity of leukemic cells that significantly influences their proliferation and resistance to stress, and thereby, the prognosis of AML patients.

Drugless nanoparticles tune-up an array of intertwined pathways contributing to immune checkpoint signaling and metabolic reprogramming in triple-negative breast cancer

Metabolic reprogramming 'Warburg effect' and immune checkpoint signaling are immunosuppressive hallmarks of triple-negative breast cancer (TNBC) contributing to the limited clinical applicability of immunotherapy. Biomaterials arise as novel tools for immunomodulation of the tumor microenvironment that can be used alongside conventional immunotherapeutics. Chitosan and lecithin are examples of versatile biomaterials with interesting immunomodulatory properties. In this study, we aimed at investigation of the role of carefully designed hybrid nanoparticles (NPs) on common mediators of both programmed death ligand 1 (PD-L1) expression and glycolytic metabolism. Hybrid lecithin-chitosan NPs were prepared and characterized. Their intracellular concentration, localization and effect on the viability of MDA-MB-231 cells were assessed. Glycolytic metabolism was quantified by measuring glucose consumption, adenosine triphosphate (ATP) generation, lactate production and extracellular acidification. Nitric oxide production was quantified using Greiss reagent. Gene expression of inducible nitric oxide synthase (iNOS), phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB or Akt), mammalian target of rapamycin (mTOR), hypoxia-inducible factor 1α(HIF-1α) and PD-L1 was quantified by quantitative reverse transcription polymerase chain reaction (q-RT-PCR). Chitosan, lecithin and the NPs-formulated forms have been shown to influence the 'Warburg effect' and immune checkpoint signaling of TNBC cells differently. The composition of the hybrid systems dictated their subcellular localization and hence the positive or negative impact on the immunosuppressive characteristics of TNBC cells. Carefully engineered hybrid lecithin-chitosan NPs could convert the immune-suppressive microenvironment of TNBC to an immune-active microenvironment via reduction of PD-L1 expression and reversal of the Warburg effect.

AMPKα2 controls the anti-atherosclerotic effects of fish oils by modulating the SUMOylation of GPR120

Consuming fish oils (FO) is linked to reduced risk of cardiovascular disease in certain populations. However, FO failed to exhibit therapeutic effects in some patients with cardiovascular disease. This study aimed to determine the possible reasons for the inconsistent effects of FO. AMP-activated protein kinase (AMPK) α2 is an important energy metabolic sensor, which was reported to involve in FO mediated regulation of lipid and glucose metabolism. In an in vivo study, FO administration significantly reduced the aortic lesions and inflammation in the Ldlr^-/- mouse model of atherosclerosis, but not in Ldlr^-/-/Prkaa2^-/-and Ldlr^-/-/Prkaa2^-/-Sm22Cre mice. Mechanistically, inactivation of AMPKα2 increased the SUMOylation of the fatty acid receptor GPR120 to block FO-induced internalization and binding to β-arrestin. In contrast, activation of AMPKα2 can phosphorylate the C-MYC at Serine 67 to inhibit its trans-localization into the nuclei and transcription of SUMO-conjugating E2 enzyme UBC9 and SUMO2/3 in vascular smooth muscle cells (VSMCs), which result in GPR120 SUMOylation. In human arteries, AMPKα2 levels were inversely correlated with UBC9 expression. In a cohort of patients with atherosclerosis, FO concentrations did not correlate with atherosclerotic severity, however, in a subgroup analysis a negative correlation between FO concentrations and atherosclerotic severity was found in patients with higher AMPKα2 levels. These data indicate that AMPKα2 is required for the anti-inflammatory and anti-atherosclerotic effects of FO.

The molecular biology and therapeutic potential of Nrf2 in leukemia

NF-E2-related factor 2 (Nrf2) transcription factor has contradictory roles in cancer, which can act as a tumor suppressor or a proto-oncogene in different cell conditions (depending on the cell type and the conditions of the cell environment). Nrf2 pathway regulates several cellular processes, including signaling, energy metabolism, autophagy, inflammation, redox homeostasis, and antioxidant regulation. As a result, it plays a crucial role in cell survival. Conversely, Nrf2 protects cancerous cells from apoptosis and increases proliferation, angiogenesis, and metastasis. It promotes resistance to chemotherapy and radiotherapy in various solid tumors and hematological malignancies, so we want to elucidate the role of Nrf2 in cancer and the positive point of its targeting. Also, in the past few years, many studies have shown that Nrf2 protects cancer cells, especially leukemic cells, from the effects of chemotherapeutic drugs. The present paper summarizes these studies to scrutinize whether targeting Nrf2 combined with chemotherapy would be a therapeutic approach for leukemia treatment. Also, we discussed how Nrf2 and NF-κB work together to control the cellular redox pathway. The role of these two factors in inflammation (antagonistic) and leukemia (synergistic) is also summarized.

Adjunction of a fish oil emulsion to cytarabine and daunorubicin induction chemotherapy in high-risk AML

The treatment of acute myeloid leukemia (AML) with unfavorable cytogenetics treatment remains a challenge. We previously established that ex vivo exposure of AML blasts to eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or fish oil emulsion (FO) induces Nrf2 pathway activation, metabolic switch, and cell death. The FILO group launched a pilot clinical study to evaluate the feasibility, safety, and efficacy of the adjunction of a commercial FO emulsion to 3 + 7 in untreated AML with unfavorable cytogenetics. The primary objective was complete response (CR). Thirty patients were included. FO administration raised the plasma levels of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (p < 0.001). The pharmacokinetics of cytarabine and daunorubicin were unaffected. A historical comparison to the LAM2001 trial (Lioure et al. Blood 2012) found a higher frequency of grade 3 serious adverse events, with no drug-related unexpected toxicity. The CR rate was 77%, and the partial response (PR) 10%, not significantly superior to that of the previous study (CR 72%, PR 1%). RT-qPCR analysis of Nrf2 target genes and antioxidant enzymes did not show a significant in vivo response. Overall, FO emulsion adjunction to 3 + 7 is feasible. An improvement in CR was not shown in this cohort of high-risk patients. The present data does not support the use of FO in adjunction with 3 + 7 in high-risk AML patients.

ClinicalTrials.gov identifier: NCT01999413.

Curcumin and NCLX inhibitors share anti-tumoral mechanisms in microsatellite-instability-driven colorectal cancer

BACKGROUND AND AIMS

Recent evidences highlight a role of the mitochondria calcium homeostasis in the development of colorectal cancer (CRC). To overcome treatment resistance, we aimed to evaluate the role of the mitochondrial sodium-calcium-lithium exchanger (NCLX) and its targeting in CRC. We also identified curcumin as a new inhibitor of NCLX.

METHODS

We examined whether curcumin and pharmacological compounds induced the inhibition of NCLX-mediated mitochondrial calcium (mtCa2+) extrusion, the role of redox metabolism in this process. We evaluated their anti-tumorigenic activity in vitro and in a xenograft mouse model. We analyzed NCLX expression and associations with survival in The Cancer Genome Atlas (TCGA) dataset and in tissue microarrays from 381 patients with microsatellite instability (MSI)-driven CRC.

RESULTS

In vitro, curcumin exerted strong anti-tumoral activity through its action on NCLX with mtCa2+ and reactive oxygen species overload associated with a mitochondrial membrane depolarization, leading to reduced ATP production and apoptosis. NCLX inhibition with pharmacological and molecular approaches reproduced the effects of curcumin. NCLX inhibitors decreased CRC tumor growth in vivo. Both transcriptomic analysis of TCGA dataset and immunohistochemical analysis of tissue microarrays demonstrated that higher NCLX expression was associated with MSI status, and for the first time, NCLX expression was significantly associated with recurrence-free survival.

CONCLUSIONS

Our findings highlight a novel anti-tumoral mechanism of curcumin through its action on NCLX and mitochondria calcium overload that could benefit for therapeutic schedule of patients with MSI CRC.

Multi-targeted therapy of cancer by omega-3 fatty acids-an update

Low in dietary ω3 polyunsaturated fatty acid (PUFA) consumption has been associated with increased incidence of cancers. Many basic and clinical studies have been conducted over the last several decades. We previously reviewed multi-targeted therapy of cancer by omega-3 fatty acids in 2008, and since hundreds of new clinical trials are being conducted to validate the effectiveness of ω3 PUFA in cancer therapy. Because of the availability of such large amount of clinical trial data, in this update we summarize clinical data, sort out trials that show promising results, and discuss potential mechanism(s) responsible for the clinical outcomes. It appears that ω3 PUFA mainly affects cancer-associated symptoms, namely cachexia, inflammation, neuropathy, post operative complications and quality of life. Mechanisms responsible for these effects are possible regulation of skeletal muscle protein turnover, inflammatory response and neuron cell survive by ω3 PUFA.

Azacitidine Omega-3 Self-Assemblies: Synthesis, Characterization, and Potent Applications for Myelodysplastic Syndromes

5-Azacitidine, a cytidine analogue used as a hypomethylating agent, is one of the main drugs for the treatment of myelodysplastic syndromes (MDSs) and acute myeloid leukemia (AML) in the elderly. However, after administration, it exhibits several limitations, including restricted diffusion and cellular internalization due to its hydrophilicity, and a rapid enzymatic degradation by adenosine deaminase. The aim of this study was to improve the drug cell diffusion and protect it from metabolic degradation via the synthesis of amphiphilic prodrugs and their potential self-assembly. Azacitidine was conjugated to two different omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The carboxylic acid group of the omega-3 fatty acids was effectively conjugated to the amine group of the azacitidine base, yielding two amphiphilic prodrugs. Nanoprecipitation of the obtained prodrugs was performed and self-assemblies were successfully obtained for both prodrugs, with a mean diameter of 190 nm, a polydispersity index below 0.2 and a positive zeta potential. The formation of self-assemblies was confirmed using pyrene as a fluorescent dye, and the critical aggregation concentrations were determined: 400 µM for AzaEPA and 688 µM for AzaDHA. Additionally, the stability of the obtained self-assemblies was studied and after 5 days their final stable arrangement was reached. Additionally, cryo-TEM revealed that the self-assemblies attain a multilamellar vesicle supramolecular structure. Moreover, the obtained self-assemblies presented promising cytotoxicity on a leukemia human cell line, having a low IC50 value, comparable to that of free azacitidine.

Eicosapentaenoic acid (EPA) exhibits antioxidant activity via mitochondrial modulation

Reactive oxygen species (ROS) are mitochondrial respiration byproducts, the accumulation of which may cause oxidative damage and is associated with several chronic health problems. As an essential unsaturated fatty acid, eicosapentaenoic acid (EPA) provides various physiological functions; however, its exact regulatory role remains elusive. The current study aimed to address how EPA regulates cellular antioxidant capacity and the possible mechanisms of action. Upon 48 h of EPA treatment, the ROS levels of HepG2 cells were reduced by at least 40%; the total cellular antioxidant capacity was increased by approximately 50-70%, accompanied by enhanced activities and expression of major antioxidant enzymes. Furthermore, the mitochondrial membrane potential and the mitochondrial biogenesis were dramatically improved in EPA-treated cells. These data suggest that EPA improves cellular antioxidant capacity by enhancing mitochondrial function and biogenesis, which sheds light on EPA as a dietary complement to relieve the oxidative damage caused by chronic diseases.

Effect of EPA on Hsp90 and GRα protein expression in multiple myeloma drug-resistant cells

BACKGROUND

Approximately 20% of MM patients harbor glucocorticoid (GC) resistance and are not responsive to therapeutic effect. Chaperoneheat-shock proteins Hsp90 is needed for ligand docking, The imbalance of Hsp90/GRα (glucocorticoid receptor α) may be an important cause of GC resistance. Recent studies have indicated that EPA could repress cancer cell growth by regulating critical influential factors in progression of cancer, consisting of resistance to drugs, chemosensitivity. The aim of the present study was to test the cytotoxic effects of EPA alone or EPA + Dexamethasone in dexamethasone-resistant MM cell (MM.1R) and investigate whether DHA can induce apoptosis and reverse acquired glucocorticoid resistance in dexamethasone-resistant MM cell (MM.1R).

METHODS

Cell Counting Kit-8 (CCK-8) was used to detect the proliferation of MM.1R cells after treating with EPA alone and EPA combined with DEX. Mitochondrial membrane potential was measured by flow cytometry and GRα and Hsp90 protein expression were assessed by western blot analysis.

RESULTS

EPA alone was able to inhibit cell proliferation as evidenced by CCK-8 assay and the tumor growth was remarkably suppressed by EPA + Dexamethasone, Cell apoptosis after EPA treatment was obviously observed by Flow cytometry analysis of the mitochondrial membrane potential. Analysis of Hsp90 and GRα proteins in MM.1R cells incubated with EPA revealed down-regulation of Hsp90 and up-regulation of GRα. Accordingly, the Hsp90/GRα ratio was significantly decreased with the increase of EPA concentration.

CONCLUSIONS

EPA might be used as a new effective treatment for reversal of glucocorticoid-resistance in multiple myeloma.

In Vitro Analysis of Energy Metabolism in Bone-Marrow Mesenchymal Stromal Cells

Bone marrow mesenchymal stromal cells (MSCs) play an essential role in the regulation of normal and leukemic hematopoiesis. Their multipotent potential of differentiation also makes them an interesting therapeutic tool. Among factors involved in the regulation of MSCs, energy metabolism plays a key role in their proliferation and differentiation. Seahorse Bioscience introduced extracellular flux technology to the life sciences market in 2006. This methodology allows, in living cells and in real time, the concomitant determination of basal oxygen consumption, glycolysis rates, ATP production, and respiratory capacity in a single experiment. Here we describe the protocol used to study concomitantly the respiratory and glycolytic metabolism of primary MSCs from the determination of oxygen consumption (OCR) and extracellular acidification (ECAR) rates.

Antioxidant Activity of Docosahexaenoic Acid (DHA) and Its Regulatory Roles in Mitochondria

Reactive oxygen species (ROS) are single-electron-bearing oxidation-reduction products that are mainly produced in mitochondria. Excessive ROS accumulation may lead to oxidative damage. Docosahexaenoic acid (DHA) is an essential component of brain phospholipids and is mainly derived from the diet. Its antioxidant activities have been extensively studied. However, its regulatory roles in mitochondria and the underlying mechanism remain to be elucidated. In this study, the DHA's effect on cellular antioxidant capacity and mitochondrial functions was examined in HepG2 cells. The results showed that 100 μM DHA decreased cellular and mitochondrial ROS levels to 75.2 ± 9.4% (P < 0.05) and 55.1 ± 1.4% (P < 0.01), respectively. It also increased the total antioxidant capacity by 55.6 ± 0.1 and 49.2 ± 1.1% (P < 0.05), based on ABTS and FRAP assay results, respectively. Consistently, it increased the activities and gene expression of major antioxidant enzymes by at least 35 and 40% (P < 0.05), respectively. Furthermore, DHA promoted mitochondrial functions and biogenesis. These data suggested that DHA's antioxidant activity can be attributed to its enhancement of mitochondrial functions and biogenesis. This study may shed light on the molecular mechanisms underlying DHA's function in improving resistance to and relieving the symptoms of chronic disease.

Therapeutic Effects of Specialized Pro-Resolving Lipids Mediators on Cardiac Fibrosis via NRF2 Activation

Heart disease is the number one mortality disease in the world. In particular, cardiac fibrosis is considered as a major factor causing myocardial infarction and heart failure. In particular, oxidative stress is a major cause of heart fibrosis. In order to control such oxidative stress, the importance of nuclear factor erythropoietin 2 related factor 2 (NRF2) has recently been highlighted. In this review, we will discuss the activation of NRF2 by docosahexanoic acid (DHA), eicosapentaenoic acid (EPA), and the specialized pro-resolving lipid mediators (SPMs) derived from polyunsaturated lipids, including DHA and EPA. Additionally, we will discuss their effects on cardiac fibrosis via NRF2 activation.

Potential use of n-3 PUFAs to prevent oxidative stress-derived ototoxicity caused by platinum-based chemotherapy

Platinum-based compounds are widely used for the treatment of different malignancies due to their high effectiveness. Unfortunately, platinum-based treatment may lead to ototoxicity, an often-irreversible side effect without a known effective treatment and prevention plan. Platinum-based compound-related ototoxicity results mainly from the production of toxic levels of reactive oxygen species (ROS) rather than DNA-adduct formation, which has led to test strategies based on direct ROS scavengers to ameliorate hearing loss. However, favorable clinical results have been associated with several complications, including potential interactions with chemotherapy efficacy. To understand the contribution of the different cytotoxic mechanisms of platinum analogues on malignant cells and auditory cells, the particular susceptibility and response of both kinds of cells to molecules that potentially interfere with these mechanisms, is fundamental to develop innovative strategies to prevent ototoxicity without affecting antineoplastic effects. The n-3 long-chain polyunsaturated fatty acids (n-3 PUFAs) have been tried in different clinical settings, including with cancer patients. Nevertheless, their use to decrease cisplatin-induced ototoxicity has not been explored to date. In this hypothesis paper, we address the mechanisms of platinum compounds-derived ototoxicity, focusing on the differences between the effects of these compounds in neoplastic versus auditory cells. We discuss the basis for a strategic use of n-3 PUFAs to potentially protect auditory cells from platinum-derived injury without affecting neoplastic cells and chemotherapy efficacy.

Comparing the In Vitro Antitumor, Antioxidant and Anti-Inflammatory Activities between Two New Very Long Chain Polyunsaturated Fatty Acids, Docosadienoic Acid (DDA) and Docosatrienoic Acid (DTA), and Docosahexaenoic Acid (DHA)

Very long chain polyunsaturated fatty acids (VLCPUFAs) are widely used as nutraceutical supplements for human health. Recently, a high level of two new VLCPUFAs, docosadienoic acid (DDA, 22:2n-6) and docosatrienoic acid (DTA, 22:3n-3), was produced in oilseed crop Brassica carinata using a biotechnology approach. This study investigated the functional properties of these two VLCPUFAs in human cells. Compared to docosahexaenoic acid (DHA), the golden standard in evaluating the health-promoting activities of VLCPUFAs, both DDA and DTA exhibited comparable or even better antitumor and antioxidant effects against human breast cancer SK-BR-3 and MDA-MB-231 cells. Especially, DTA elicited much stronger antioxidant and pro-apoptotic effects than DHA. Furthermore, DDA and DTA showed strong anti-inflammatory effects in human macrophages differentiated from monocyte THP-1 cells through lowering the protein expression levels of pro-inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon γ (IFN-γ), monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor α (TNF-α). Future In Vivo and In Vivo studies are warranted to identify the mechanism of action (MOA) for the antitumor, antioxidant and anti-inflammatory functions of DDA and DTA and explore potential applications of these two VLCPUFAs as novel nutraceutical supplements in preventing inflammatory conditions, aging and even cancer.

Dietary Fat and Cancer-Which Is Good, Which Is Bad, and the Body of Evidence

A high-fat diet (HFD) induces changes in gut microbiota leading to activation of pro-inflammatory pathways, and obesity, as a consequence of overnutrition, exacerbates inflammation, a known risk factor not only for cancer. However, experimental data showed that the composition of dietary fat has a greater impact on the pathogenesis of cancer than the total fat content in isocaloric diets. Similarly, human studies did not prove that a decrease in total fat intake is an effective strategy to combat cancer. Saturated fat has long been considered as harmful, but the current consensus is that moderate intake of saturated fatty acids (SFAs), including palmitic acid (PA), does not pose a health risk within a balanced diet. In regard to monounsaturated fat, plant sources are recommended. The consumption of plant monounsaturated fatty acids (MUFAs), particularly from olive oil, has been associated with lower cancer risk. Similarly, the replacement of animal MUFAs with plant MUFAs decreased cancer mortality. The impact of polyunsaturated fatty acids (PUFAs) on cancer risk depends on the ratio between ω-6 and ω-3 PUFAs. In vivo data showed stimulatory effects of ω-6 PUFAs on tumour growth while ω-3 PUFAs were protective, but the results of human studies were not as promising as indicated in preclinical reports. As for trans FAs (TFAs), experimental data mostly showed opposite effects of industrially produced and natural TFAs, with the latter being protective against cancer progression, but human data are mixed, and no clear conclusion can be made. Further studies are warranted to establish the role of FAs in the control of cell growth in order to find an effective strategy for cancer prevention/treatment.

Human hematopoietic stem/progenitor cells display reactive oxygen species-dependent long-term hematopoietic defects after exposure to low doses of ionizing radiations

Hematopoietic stem cells are responsible for life-long blood cell production and are highly sensitive to exogenous stresses. The effects of low doses of ionizing radiations on radiosensitive tissues such as the hematopoietic tissue are still unknown despite their increasing use in medical imaging. Here, we study the consequences of low doses of ionizing radiations on differentiation and self-renewal capacities of human primary hematopoietic stem/progenitor cells (HSPC). We found that a single 20 mGy dose impairs the hematopoietic reconstitution potential of human HSPC but not their differentiation properties. In contrast to high irradiation doses, low doses of irradiation do not induce DNA double strand breaks in HSPC but, similar to high doses, induce a rapid and transient increase of reactive oxygen species (ROS) that promotes activation of the p38MAPK pathway. HSPC treatment with ROS scavengers or p38MAPK inhibitor prior exposure to 20 mGy irradiation abolishes the 20 mGy-induced defects indicating that ROS and p38MAPK pathways are transducers of low doses of radiation effects. Taken together, these results show that a 20 mGy dose of ionizing radiation reduces the reconstitution potential of HSPC suggesting an effect on the self-renewal potential of human hematopoietic stem cells and pinpointing ROS or the p38MAPK as therapeutic targets. Inhibition of ROS or the p38MAPK pathway protects human primary HSPC from low-dose irradiation toxicity.

Disruption of gap junctions attenuates acute myeloid leukemia chemoresistance induced by bone marrow mesenchymal stromal cells

The bone marrow (BM) niche impacts the progression of acute myeloid leukemia (AML) by favoring the chemoresistance of AML cells. Intimate interactions between leukemic cells and BM mesenchymal stromal cells (BM-MSCs) play key roles in this process. Direct intercellular communications between hematopoietic cells and BM-MSCs involve connexins, components of gap junctions. We postulated that blocking gap junction assembly could modify cell–cell interactions in the leukemic niche and consequently the chemoresistance. The comparison of BM-MSCs from AML patients and healthy donors revealed a specific profile of connexins in BM-MSCs of the leukemic niche and the effects of carbenoxolone (CBX), a gap junction disruptor, were evaluated on AML cells. CBX presents an antileukemic effect without affecting normal BM-CD34⁺ progenitor cells. The proapoptotic effect of CBX on AML cells is in line with the extinction of energy metabolism. CBX acts synergistically with cytarabine (Ara-C) in vitro and in vivo. Coculture experiments of AML cells with BM-MSCs revealed that CBX neutralizes the protective effect of the niche against the Ara-C-induced apoptosis of leukemic cells. Altogether, these results suggest that CBX could be of therapeutic interest to reduce the chemoresistance favored by the leukemic niche, by targeting gap junctions, without affecting normal hematopoiesis.

EPA and DHA have selective toxicity for PBMCs from multiple myeloma patients in a partly caspase-dependent manner

Poly-unsaturated fatty acids (PUFAs) have been shown to have cytotoxic effects in both solid and non-solid tumors. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are among the most studied PUFAs. The aim of the present study was to evaluate the cytotoxic effects of these two fatty acids (FAs) in the peripheral blood mononuclear cells (PBMCs) obtained from untreated patients (new cases) with confirmed symptomatic multiple myeloma (MM). Our results showed that EPA at the concentration of 100 μM and DHA at 50 and 100 μM induce potent apoptotic effects in the PBMCs of MM patients (P < 0.05) as evidenced by Annexin V and propidium iodide (PI) staining, while they have little or no effects on the PBMCs isolated from healthy donors (P > 0.05). The observed effects were concentration- and time-dependent and 72 h treatment with DHA at a concentration of 100 μM had the strongest effect (P < 0.01). CD138 + cells isolated from MM patients showed great sensitivity to EPA/DHA. EPA- and DHA-induced apoptosis was significantly inhibited by the pan-caspase inhibitor (Z-VAD-FMK), indicating that cell death was at least partly dependent on caspase activation. The results of the present study showed that EPA and DHA have selective toxicities for malignant human plasma cells from MM patients, but not for mononuclear cells of healthy donors. These results warrant further studies with larger study populations to investigate the usefulness of PUFAs as a promising adjunctive therapy in the treatment of MM.