Antitumorigenic Properties of Omega-3 Endocannabinoid Epoxides

CB65 and novel CB65 liposomal system suppress MG63 and Saos-2 osteosarcoma cell growth in vitro

Curable approaches for primary osteosarcoma are inadequate and urge investigation of novel therapeutic formulations. Cannabinoid ligands exert antiproliferative and apoptotic effect on osteosarcoma cells via cannabinoid 2 (CB2) or transient receptor potential vanilloid type (TRPV1) receptors. In this study, we confirmed CB2 receptor expression in MG63 and Saos-2 osteosarcoma cells by qRT-PCR and flow cytometry (FCM), then reported the reduction effect of synthetic specific CB2 receptor agonist CB65 on the proliferation of osteosarcoma cells by WST-1 (water-soluble tetrazolium-1) and RTCA (real-time impedance-based proliferation). CB65 revealed an IC50 (inhibitory concentration) for MG63 and Saos-2 cells as 1.11 × 10-11 and 4.95 × 10-11 M, respectively. The specific antiproliferative effect of CB65 on osteosarcoma cells was inhibited by CB2 antagonist AM630. CB65 induced late apoptosis of MG63 and Saos-2 cells at 24 and 48 h, respectively by FCM when applied submaximal concentration. A novel CB65 liposomal system was generated by a thin film hydration method with optimal particle size (141.7 ± 0.6 nm), polydispersity index (0.451 ± 0.026), and zeta potential (-10.9 ± 0.3 mV) values. The encapsulation efficiency (EE%) of the CB65-loaded liposomal formulation was 51.12%. The CB65 and CB65-loaded liposomal formulation releasing IC50 of CB65 reduced proliferation by RTCA and invasion by scratch assay and induced late apoptosis of MG63 and Saos-2 cells, by FCM. Our results demonstrate the CB2 receptor-mediated antiproliferative and apoptotic effect of a new liposomal CB65 delivery system on osteosarcoma cells that can be used as a targeted and intelligent tool for bone tumors to ameliorate pediatric bone cancers following in vivo validation.

Omega-3 polyunsaturated fatty acid derived lipid mediators: a comprehensive update on their application in anti-cancer drug discovery

INTRODUCTION

ω-3 Polyunsaturated fatty acids (PUFAs) have a range of health benefits, including anticancer activity, and are converted to lipid mediators that could be adapted into pharmacological strategies. However, the stability of these mediators must be improved, and they may require formulation to achieve optimal tissue concentrations.

AREAS COVERED

Herein, the author reviews the literature around chemical stabilization and formulation of ω-3 PUFA mediators and their application in anticancer drug discovery.

EXPERT OPINION

Aryl-urea bioisosteres of ω-3 PUFA epoxides that killed cancer cells targeted the mitochondrion by a novel dual mechanism: as protonophoric uncouplers and as inhibitors of electron transport complex III that activated ER-stress and disrupted mitochondrial integrity. In contrast, aryl-ureas that contain electron-donating substituents prevented cancer cell migration. Thus, aryl-ureas represent a novel class of agents with tunable anticancer properties. Stabilized analogues of other ω-3 PUFA-derived mediators could also be adapted into anticancer strategies. Indeed, a cocktail of agents that simultaneously promote cell killing, inhibit metastasis and angiogenesis, and that attenuate the pro-inflammatory microenvironment is a novel future anticancer strategy. Such regimen may enhance anticancer drug efficacy, minimize the development of anticancer drug resistance and enhance outcomes.

Lipid metabolism-derived FAAH is a sensitive marker for the prognosis and immunotherapy of osteosarcoma patients

Lipid metabolism in cancer refers to the alterations in how cancer cells process and utilize lipids, a type of fat molecule. It was investigated how lipid metabolism relates to osteosarcoma. Genes relevant to lipid metabolism were gathered to create lipid metabolism-associated clusters and locate the dangerous marker. We investigated FAAH's prognostic significance, route annotation, immunotherapy response, and medication prediction. Besides, FAAH is proven to be a potent, dangerous marker that may promote growth and migration and inhibit the apoptosis of osteosarcoma. FAAH exhibits higher expression levels in tumor tissues as compared to normal tissues. In conclusion, FAAH is identified in this work as a potentially dangerous gene and immunotherapy determinant. This study requires more investigation to determine how FAAH influences the immune response in osteosarcoma.

Role of omega-3 and omega-6 endocannabinoids in cardiopulmonary pharmacology

Endocannabinoids are derived from dietary omega-3 and omega-6 fatty acids and play an important role in regulation of inflammation, development, neurodegenerative diseases, cancer, and cardiovascular diseases. They elicit this effect via interactions with cannabinoid receptors 1 and 2 which are also targeted by plant derived cannabinoid from cannabis. The evidence of the involvement of the endocannabinoid system in cardiopulmonary function comes from studies that show that cannabis consumption leads to cardiovascular effect such as arrythmia and is beneficial in lung cancer patients. Moreover, omega-3 and omega-6 endocannabinoids play several important roles in cardiopulmonary system such as causing airway relaxation, suppressing atherosclerosis and hypertension. These effects are mediated via the cannabinoids receptors that are abundant in the cardiopulmonary system. Overall, this chapter reviews the known role of phytocannabinoids and endocannabinoids in the cardiopulmonary context.

Anandamide and other N-acylethanolamines: A class of signaling lipids with therapeutic opportunities

N-acylethanolamines (NAEs), including N-palmitoylethanolamine (PEA), N-oleoylethanolamine (OEA), N-arachidonoylethanolamine (AEA, anandamide), N-docosahexaenoylethanolamine (DHEA, synaptamide) and their oxygenated metabolites are a lipid messenger family with numerous functions in health and disease, including inflammation, anxiety and energy metabolism. The NAEs exert their signaling role through activation of various G protein-coupled receptors (cannabinoid CB₁ and CB₂ receptors, GPR55, GPR110, GPR119), ion channels (TRPV1) and nuclear receptors (PPAR-α and PPAR-γ) in the brain and periphery. The biological role of the oxygenated NAEs, such as prostamides, hydroxylated anandamide and DHEA derivatives, are less studied. Evidence is accumulating that NAEs and their oxidative metabolites may be aberrantly regulated or are associated with disease severity in obesity, metabolic syndrome, cancer, neuroinflammation and liver cirrhosis. Here, we comprehensively review NAE biosynthesis and degradation, their metabolism by lipoxygenases, cyclooxygenases and cytochrome P450s and the biological functions of these signaling lipids. We discuss the latest findings and therapeutic potential of modulating endogenous NAE levels by inhibition of their degradation, which is currently under clinical evaluation for neuropsychiatric disorders. We also highlight NAE biosynthesis inhibition as an emerging topic with therapeutic opportunities in endocannabinoid and NAE signaling.

Cannabinoid CB1 receptors regulate salivation

Saliva serves multiple important functions within the body that we typically take for granted, such as helping prepare food for swallowing and defense against oral pathogens. Dry mouth is a primary symptom of Sjӧgren’s syndrome and is a side effect of many drug treatments. Cannabis users frequently report dry mouth, but the basis for this is still unknown. If the effects occur via the endogenous cannabinoid signaling system, then this may represent a novel mechanism for the regulation of salivation. We examined expression of cannabinoid CB1 receptors in submandibular salivary gland using immunohistochemistry and tested regulation of salivation by THC and cannabinoid-related ligands. We now report that CB1 receptors are expressed in the axons of cholinergic neurons innervating the submandibular gland. No staining is seen in submandibular gland epithelial cells (acinar and ductal), or myoepithelial cells (MECs). Treatment with THC (4 mg/kg, IP) or the cannabinoid receptor agonist CP55940 (0.5 mg/kg) reduced salivation in both male and female mice 1 h after treatment. CBD had no effect on its own but reversed the effect of THC in a concentration-dependent manner. Neither the CB1 receptor antagonist SR141716 (4 mg/kg) nor the CB2-selective agonist JWH133 (4 mg/kg) had an effect on salivation. We also found that fatty acid amide hydrolase (FAAH), the enzyme that metabolizes the endocannabinoid anandamide and related lipids, regulates salivation. Salivation was reduced in FAAH knockout mice as well as mice treated with the FAAH blocker URB597 (4 mg/kg). URB597 had no effect in CB1 knockout mice. FAAH protein is detected intracellularly in acinar but not ductal epithelial cells. In lipidomics experiments, we found that FAAH knockout mice chiefly had elevated levels of acylethanolamines, including anandamide, and reduced levels of acyglycines. Our results are consistent with a model wherein endocannabinoids activate CB1 receptors on cholinergic axons innervating the submandibular gland. THC likely acts by plugging into this system, activating CB1 receptors to reduce salivation, thus offering a mechanism underlying the dry mouth reported by cannabis users.

PUFA-Derived N-Acylethanolamide Probes Identify Peroxiredoxins and Small GTPases as Molecular Targets in LPS-Stimulated RAW264.7 Macrophages

We studied the mechanistic and biological origins of anti-inflammatory poly-unsaturated fatty acid-derived N-acylethanolamines using synthetic bifunctional chemical probes of docosahexaenoyl ethanolamide (DHEA) and arachidonoyl ethanolamide (AEA) in RAW264.7 macrophages stimulated with 1.0 μg mL^-1 lipopolysaccharide. Using a photoreactive diazirine, probes were covalently attached to their target proteins, which were further studied by introducing a fluorescent probe or biotin-based affinity purification. Fluorescence confocal microscopy showed DHEA and AEA probes localized in cytosol, specifically in structures that point toward the endoplasmic reticulum and in membrane vesicles. Affinity purification followed by proteomic analysis revealed peroxiredoxin-1 (Prdx1) as the most significant binding interactor of both DHEA and AEA probes. In addition, Prdx4, endosomal related proteins, small GTPase signaling proteins, and prostaglandin synthase 2 (Ptgs2, also known as cyclooxygenase 2 or COX-2) were identified. Lastly, confocal fluorescence microscopy revealed the colocalization of Ptgs2 and Rac1 with DHEA and AEA probes. These data identified new molecular targets suggesting that DHEA and AEA may be involved in reactive oxidation species regulation, cell migration, cytoskeletal remodeling, and endosomal trafficking and support endocytosis as an uptake mechanism.

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.

Osteosarcoma in Children: Not Only Chemotherapy

Osteosarcoma (OS) is the most severe bone malignant tumor, responsible for altered osteoid deposition and with a high rate of metastasis. It is characterized by heterogeneity, chemoresistance and its interaction with bone microenvironment. The 5-year survival rate is about 67% for patients with localized OS, while it remains at 20% in case of metastases. The standard therapy for OS patients is represented by neoadjuvant chemotherapy, surgical resection, and adjuvant chemotherapy. The most used chemotherapy regimen for children is the combination of high-dose methotrexate, doxorubicin, and cisplatin. Considered that the necessary administration of high-dose chemotherapy is responsible for a lot of acute and chronic side effects, the identification of novel therapeutic strategies to ameliorate OS outcome and the patients' life expectancy is necessary. In this review we provide an overview on new possible innovative therapeutic strategies in OS.

Biocatalytic regio- and stereoselective access to ω-3 endocannabinoid epoxides with peroxygenase from oat flour

The biocatalytic epoxidation of ethanolamides of ω-3 fatty acids EPA and DHA, regarded as biologically active ω-3 endocannabinoids, in the presence of a peroxygenase-containing preparation from oat flour was investigated. Good regio- and steroselectivity toward the formation of the epoxide on the terminal double bond in the chain was observed with both these fatty acid derivatives and chiral monoepoxides 1 or 2 in 74% optical purity and 51-53% yields were isolated and spectroscopically characterized. The use of acetone as cosolvent in the reaction medium allowed to increase the concentration of starting substrates up to 40 mM and to further improve the selectivity in the epoxidation of DHA-EA. Due to the easy availability of the enzymatic preparation, the method offers a valuable strategy for the access to oxyfunctionalized derivatives of fatty acids.

Immunomodulating effects of 13- and 16-hydroxylated docosahexaenoyl ethanolamide in LPS stimulated RAW264.7 macrophages

Docosahexaenoyl ethanolamide (DHEA), the ethanolamine conjugate of the n-3 long chain polyunsaturated fatty acid docosahexaenoic acid, is endogenously present in the human circulation and in tissues. Its immunomodulating properties have been (partly) attributed to an interaction with the cyclooxygenase-2 (COX-2) enzyme. Recently, we discovered that COX-2 converts DHEA into two oxygenated metabolites, 13- and 16-hydroxylated-DHEA (13- and 16-HDHEA, respectively). It remained unclear whether these oxygenated metabolites also display immunomodulating properties like their parent DHEA. In the current study we investigated the immunomodulating properties of 13- and 16-HDHEA in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The compounds reduced production of tumor necrosis factor alpha (TNFα), interleukin (IL)-1β and IL-1Ra, but did not affect nitric oxide (NO) and IL-6 release. Transcriptome analysis showed that the compounds inhibited the LPS-mediated induction of pro-inflammatory genes (InhbA, Ifit1) and suggested potential inhibition of regulators such as toll-like receptor 4 (TLR4), MyD88, and interferon regulatory factor 3 (IRF3), whereas anti-inflammatory genes (SerpinB2) and potential regulators IL-10, sirtuin 1 (Sirt-1), fluticasone propionate were induced. Additionally, transcriptome analysis of 13-HDHEA suggests a potential anti-angiogenic role. In contrast to the known oxylipin-lowering effects of DHEA, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analyses revealed that 13- and 16-HDHEA did not affect oxylipin formation. Overall, the anti-inflammatory effects of 13-HDHEA and 16-HDHEA are less pronounced compared to their parent molecule DHEA. Therefore, we propose that COX-2 metabolism of DHEA acts as a regulatory mechanism to limit the anti-inflammatory properties of DHEA.

Anti-inflammatory dopamine- and serotonin-based endocannabinoid epoxides reciprocally regulate cannabinoid receptors and the TRPV1 channel

The endocannabinoid system is a promising target to mitigate pain as the endocannabinoids are endogenous ligands of the pain-mediating receptors—cannabinoid receptors 1 and 2 (CB1 and CB2) and TRPV1. Herein, we report on a class of lipids formed by the epoxidation of N-arachidonoyl-dopamine (NADA) and N-arachidonoyl-serotonin (NA5HT) by epoxygenases. EpoNADA and epoNA5HT are dual-functional rheostat modulators of the endocannabinoid-TRPV1 axis. EpoNADA and epoNA5HT are stronger modulators of TRPV1 than either NADA or NA5HT, and epoNA5HT displays a significantly stronger inhibition on TRPV1-mediated responses in primary afferent neurons. Moreover, epoNA5HT is a full CB1 agonist. These epoxides reduce the pro-inflammatory biomarkers IL-6, IL-1β, TNF-α and nitrous oxide and raise anti-inflammatory IL-10 cytokine in activated microglial cells. The epoxides are spontaneously generated by activated microglia cells and their formation is potentiated in the presence of anandamide. Detailed kinetics and molecular dynamics simulation studies provide evidence for this potentiation using the epoxygenase human CYP2J2. Taken together, inflammation leads to an increase in the metabolism of NADA, NA5HT and other eCBs by epoxygenases to form the corresponding epoxides. The epoxide metabolites are bioactive lipids that are potent, multi-faceted molecules, capable of influencing the activity of CB1, CB2 and TRPV1 receptors.

Endocannabinoids are ligands of cannabinoid receptors and a promising target for pain management. Here, the authors report a class of lipids formed by the epoxidation of N-arachidonoyl dopamine and N-arachidonoyl serotonin by cytochrome P450 epoxygenases, which reciprocally regulate canabinoid receptors and display anti-inflammatory activity.

Synthesis and discovery of ω-3 polyunsaturated fatty acid- alkanolamine (PUFA-AA) derivatives as anti-inflammatory agents targeting Nur77

In this work, three series of ω-3 polyunsaturated fatty acid-alkanolamine derivatives (PUFA-AAs) were synthesized, characterized and their anti-inflammatory activity in vivo was evaluated. Compounds 4a, 4f, and 4k exhibited marked anti-inflammatory activity in LPS-stimulated RAW 264.7 cells. The most promising compound 4k dose-dependently suppressed the cytokines with IC₅₀ values in the low micromolar range. Further, 4k exhibited potential in vitro Nur77-binding affinity (K_d = 6.99 × 10^-6 M) which is consistent with the result of docking studies. Next, the anti-inflammatory mechanism of 4k was found to be through NF-κB signal pathway in a Nur77-dependent manner. Moreover, we also observed 4k significantly inhibited LPS-induced expression of cytokines (IL-6, TNF-α, and IL-1β) through suppressing NF-κB activation and attenuated LPS-induced inflammation in mouse acute lung injury (ALI) model. In conclusion, the study strongly suggests that the PUFA-AA derivatives can be particularly as new Nur77 mediators for further treatment in inflammatory diseases.

CYP2J2 Molecular Recognition: A New Axis for Therapeutic Design

Cytochrome P450 (CYP) epoxygenases are a special subset of heme-containing CYP enzymes capable of performing the epoxidation of polyunsaturated fatty acids (PUFA) and the metabolism of xenobiotics. This dual functionality positions epoxygenases along a metabolic crossroad. Therefore, structure-function studies are critical for understanding their role in bioactive oxy-lipid synthesis, drug-PUFA interactions, and for designing therapeutics that directly target the epoxygenases. To better exploit CYP epoxygenases as therapeutic targets, there is a need for improved understanding of epoxygenase structure-function. Of the characterized epoxygenases, human CYP2J2 stands out as a potential target because of its role in cardiovascular physiology. In this review, the early research on the discovery and activity of epoxygenases is contextualized to more recent advances in CYP epoxygenase enzymology with respect to PUFA and drug metabolism. Additionally, this review employs CYP2J2 epoxygenase as a model system to highlight both the seminal works and recent advances in epoxygenase enzymology. Herein we cover CYP2J2's interactions with PUFAs and xenobiotics, its tissue-specific physiological roles in diseased states, and its structural features that enable epoxygenase function. Additionally, the enumeration of research on CYP2J2 identifies the future needs for the molecular characterization of CYP2J2 to enable a new axis of therapeutic design.

Synthesis of Two Stereoisomers of Potentially Bioactive 13,19,20-Trihydroxy Derivative of Docosahexaenoic Acid

The C16-C22 fragment with the acetylene terminus was constructed through the asymmetric dihydroxylation of the corresponding olefin, while the 15-iodo-olefin corresponding to the C11-C15 part was prepared via the asymmetric transfer hydrogenation of the corresponding acetylene ketone followed by hydrozirconation/iodination. Both pieces were joined by a Sonogashira coupling, and the product was further converted into the title compound via a Wittig reaction with the remaining C1-C10 segment and Boland reduction using Zn with TMSCl.

Quantitative Lipidomic Analysis of Osteosarcoma Cell-Derived Products by UHPLC-MS/MS

Changes in lipid metabolism are involved in several pathological conditions, such as cancer. Among lipids, eicosanoids are potent inflammatory mediators, synthesized from polyunsaturated fatty acids (PUFAs), which coexist with other lipid-derived ones, including endocannabinoids (ECs) and N-acylethanolamides (NAEs). In this work, a bioanalytical assay for 12 PUFAs/eicosanoids and 20 ECs/NAEs in cell culture medium and human biofluids was validated over a linear range of 0.1-2.5 ng/mL. A fast pretreatment method consisting of protein precipitation with acetonitrile followed by a double step liquid-liquid extraction was developed. The final extracts were injected onto a Kinetex ultra-high-performance liquid chromatography (UHPLC) XB-C18 column with a gradient elution of 0.1% formic acid in water and methanol/acetonitrile (5:1; v/v) mobile phase. Chromatographic separation was followed by detection with a triple-quadrupole mass spectrometer operating both in positive and negative ion-mode. A full validation was carried out in a small amount of cell culture medium and then applied to osteosarcoma cell-derived products. To the best of our knowledge, this is the first lipid profiling of bone tumor cell lines (SaOS-2 and MG-63) and their secretome. Our method was also partially validated in other biological matrices, such as serum and urine, ensuring its broad applicability as a powerful tool for lipidomic translational research.

Omega-3 Polyunsaturated Fatty Acids and Lung Cancer: nutrition or Pharmacology?

Omega-3 polyunsaturated fatty acid (ω-3 PUFA) supplements for chemoprevention of different types of cancer including lung cancer has been investigated in recent years. ω-3 PUFAs are considered immunonutrients, commonly used in the nutritional therapy of cancer patients. ω-3 PUFAs play essential roles in cell signaling and in cell structure and fluidity of membranes. They participate in the resolution of inflammation and have anti-inflammatory effects. Lung cancer patients suffer complications, such as anorexia-cachexia syndrome, pain and depression. The European Society for Clinical Nutrition and Metabolism (ESPEN) 2017 guidelines for cancer patients only discuss the use of ω-3 PUFAs for cancer-cachexia treatment, leaving aside other cancer-related complications that could potentially be managed by ω-3 PUFAs. This review aims to elucidate whether the effects of ω-3 PUFAs in lung cancer is supplementary, pharmacological or both. In addition, clinical studies, evidence in cell lines and animal models suggest how ω-3 PUFAs induce anticancer effects. ω-3 PUFAs and their metabolites are suggested to modulate pivotal pathways underlying the progression or complications of lung cancer, indicating that this is a promising field to be explored. Further investigation is still required to analyze the benefits of ω-3 PUFAs as supplementation or pharmacological treatment in lung cancer.

Novel COX-2 products of n-3 polyunsaturated fatty acid-ethanolamine-conjugates identified in RAW264.7 macrophages

Cyclooxygenase 2 (COX-2) plays a key role in the regulation of inflammation by catalyzing the oxygenation of PUFAs to prostaglandins (PGs) and hydroperoxides. Next to this, COX-2 can metabolize neutral lipids, including endocannabinoid-like esters and amides. We developed an LC-HRMS-based human recombinant (h)COX-2 screening assay to examine its ability to also convert n-3 PUFA-derived N-acylethanolamines. Our assay yields known hCOX-2-derived products from established PUFAs and anandamide. Subsequently, we proved that eicosapentaenoylethanolamide (EPEA), the N-acylethanolamine derivative of EPA, is converted into PGE₃-ethanolamide (PGE₃-EA), and into 11-, 14-, and 18-hydroxyeicosapentaenoyl-EA (11-, 14-, and 18-HEPE-EA, respectively). Interestingly, we demonstrated that docosahexaenoylethanolamide (DHEA) is converted by hCOX-2 into the previously unknown metabolites, 13- and 16-hydroxy-DHEA (13- and 16-HDHEA, respectively). These products were also produced by lipopolysaccharide-stimulated RAW267.4 macrophages incubated with DHEA. No oxygenated DHEA metabolites were detected when the selective COX-2 inhibitor, celecoxib, was added to the cells, further underlining the role of COX-2 in the formation of the novel hydroxylated products. This work demonstrates for the first time that DHEA and EPEA are converted by COX-2 into previously unknown hydroxylated metabolites and invites future studies toward the biological effects of these metabolites.

The role of n-3 PUFA-derived fatty acid derivatives and their oxygenated metabolites in the modulation of inflammation

Notwithstanding the ongoing debate on their full potential in health and disease, there is general consensus that n-3 PUFAs play important physiological roles. Increasing dietary n-3 PUFA intake results in increased DHA and EPA content in cell membranes as well as an increase in n-3 derived oxylipin and -endocannabinoid concentrations, like fatty acid amides and glycerol-esters. These shifts are believed to (partly) explain the pharmacological and anti-inflammatory effects of n-3 PUFAs. Recent studies discovered that n-3 PUFA-derived endocannabinoids can be further metabolized by the oxidative enzymes CYP-450, LOX and COX, similar to the n-6 derived endocannabinoids. Interestingly, these oxidized n-3 PUFA derived endocannabinoids of eicosapentaenoyl ethanolamide (EPEA) and docosahexaenoyl ethanolamide (DHEA) have higher anti-inflammatory and anti-proliferative potential than their precursors. In this review, an overview of recently discovered n-3 PUFA derived endocannabinoids and their metabolites is provided. In addition, the use of chemical probes will be presented as a promising technique to study the n-3 PUFA and n-3 PUFA metabolism within the field of lipid biochemistry.

The Endocannabinoid/Endovanilloid System in Bone: From Osteoporosis to Osteosarcoma

Bone is a dynamic tissue, whose homeostasis is maintained by a fine balance between osteoclast (OC) and osteoblast (OB) activity. The endocannabinoid/endovanilloid (EC/EV) system’s receptors are the cannabinoid receptor type 1 (CB1), the cannabinoid receptor type 2 (CB2), and the transient receptor potential cation channel subfamily V member 1 (TRPV1). Their stimulation modulates bone formation and bone resorption. Bone diseases are very common worldwide. Osteoporosis is the principal cause of bone loss and it can be caused by several factors such as postmenopausal estrogen decrease, glucocorticoid (GC) treatments, iron overload, and chemotherapies. Studies have demonstrated that CB1 and TRPV1 stimulation exerts osteoclastogenic effects, whereas CB2 stimulation has an anti-osteoclastogenic role. Moreover, the EC/EV system has been demonstrated to have a role in cancer, favoring apoptosis and inhibiting cell proliferation. In particular, in bone cancer, the modulation of the EC/EV system not only reduces cell growth and enhances apoptosis but it also reduces cell invasion and bone pain in mouse models. Therefore, EC/EV receptors may be a useful pharmacological target in the prevention and treatment of bone diseases. More studies to better investigate the biochemical mechanisms underlining the EC/EV system effects in bone are needed, but the synthesis of hybrid molecules, targeting these receptors and capable of oppositely regulating bone homeostasis, seems to be a promising and encouraging prospective in bone disease management.

Novel Anti-inflammatory and Vasodilatory ω-3 Endocannabinoid Epoxide Regioisomers

Accumulating evidence suggests that diets rich in ω-3 polyunsaturated fatty acids (PUFAs) offer protection against vascular inflammation, neuroinflammation, hypertension, and thrombosis. Recently, biochemical studies have demonstrated that these benefits are partially mediated by their conversion to ω-3 endocannabinoid epoxide metabolites. These lipid metabolites originate from the epoxidation of ω-3 endocannabinoids, docosahexanoyl ethanolamide (DHEA) and eicosapentaenoyl ethanolamide (EPEA) by cytochrome P450 (CYP) epoxygenases to form epoxydocosapentaenoic acid-ethanolamides (EDP-EAs) and epoxyeicosatetraenoic acid-ethanolamides (EEQ-EAs), respectively. The EDP-EAs and EEQ-EAs are endogenously produced in rat brain and peripheral organs. Additionally, EDP-EAs and EEQ-EAs dose-dependently decrease pro-inflammatory IL-6 cytokine and increased anti-inflammatory IL-10 cytokine. Furthermore, the EEQ-EAs and EDP-EAs attenuate angiogenesis and cell migration in cancer cells, induce vasodilation in bovine coronary arteries, and reciprocally regulate platelet aggregation in washed human platelets. Taken together, the ω-3 endocannabinoid epoxides represent a new class of dual acting molecules that display unique pharmacological properties.

Are Long-Chain Polyunsaturated Fatty Acids the Link between the Immune System and the Microbiome towards Modulating Cancer?

Three recent studies revealed synergy between immune-checkpoint inhibitors and the microbiome as a new approach in the treatment of cancer. Incidentally, there has been significant progress in understanding the role of polyunsaturated fatty acids (PUFAs) in modulating cancer and the immune system, as well as in regulating the microbiome. Inflammation seems to be the common denominator among these seemingly unrelated biological entities-immune system, the microbiome, and long-chain polyunsaturated fatty acids (LC-PUFAs). This commentary presents a hypothesis proposing the existence of an optimal level of LC-PUFAs that nurtures the suitable gut microbiota preventing dysbiosis. This synergy between optimal LC-PUFAs and gut microbiota helps the immune system overcome the immunosuppressive tumour microenvironment including enhancing the efficacy of immune checkpoint inhibitors. A model on how LC-PUFAs (such as omega(n)-3 and n-6 fatty acids) forms a synergistic triad with the immune system and the microbiome in regulating inflammation to maintain homeostasis is presented. The principles underlying the hypothesis provide a basis in managing and even preventing cancer and other chronic diseases associated with inflammation.

Breakthroughs in Medicinal Chemistry: New Targets and Mechanisms, New Drugs, New Hopes-3

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