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It is desired to selectively kill tumor cells with little or no action on normal cells. Current treatment options are associated with significant side effects including therapy with immune check point inhibitors (ICI). ICI therapy induced side effects are due to excess production of pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). At the same time, production of appropriate amounts of IL-6 and TNF-α are needed to eliminate tumor cells. Hence, methods are needed that can selectively eliminate tumor cells and tone down the side effects of cytokine storm. Studies showed that IL-6 and TNF-α activate phospholipases to induce the release of polyunsaturated fatty acids (PUFAs) from the cell membrane phospholipid pool. PUFAs form precursors to pro- and anti-inflammatory eicosanoids and are capable of suppressing IL-6 and TNF-α excess production. PUFAs are endowed with capacity to selectively kill tumor cells by augmenting free radical generation and accumulation of toxic lipid peroxides in tumor but not normal cells. NK cells, TILs (tumor infiltrating cells) and γδ T cells release toxic granules (also called as cytolytic granules) that contain unsaturated fatty acids localized between the granule delimiting membrane and the granule core. Thus, lipids are a universal component of cytolytic granules and play an important role in their cytotoxic actions. Based on this evidence, it is suggested that a combination of ICI/TILs and PUFAs may form a novel method of eliminating cancer with few side effects., (Copyright © 2019 IMSS. Published by Elsevier Inc. All rights reserved.)

Radiation induces overexpression and activity of the MET oncogene that, in turn, enhances the production of prostaglandin E(2), a pro-inflammatory molecule. Prostaglandin E(2) promotes tumor cell invasion, prevents apoptosis, enhances their metastasis and causes radioresistance. It is proposed that lipoxin A(4), a potent endogenous anti-inflammatory molecule, opposes the actions of prostaglandin E(2) and thus, could promote radiosensitivity, suppress tumor cell proliferation, invasiveness and suppress metastasis. Thus, methods designed to enhance endogenous lipoxin A(4) formation or its synthetic analogs may be useful in the management of cancer., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Stem cells are pluripotent and expected to be of benefit in the management of coronary heart disease, stroke, diabetes mellitus, cancer, and Alzheimer's disease in which pro-inflammatory cytokines are increased. Identifying endogenous bioactive molecules that have a regulatory role in stem cell survival, proliferation, and differentiation may aid in the use of stem cells in various diseases including cancer. Essential fatty acids form precursors to both pro- and anti-inflammatory molecules have been shown to regulate gene expression, enzyme activity, modulate inflammation and immune response, gluconeogenesis via direct and indirect pathways, function directly as agonists of a number of G protein-coupled receptors, activate phosphatidylinositol 3-kinase/Akt and p44/42 mitogen-activated protein kinases, and stimulate cell proliferation via Ca(2+), phospholipase C/protein kinase, events that are also necessary for stem cell survival, proliferation, and differentiation. Hence, it is likely that bioactive lipids play a significant role in various diseases by modulating the proliferation and differentiation of embryonic stem cells in addition to their capacity to suppress inflammation. Ephrin Bs and reelin, adhesion molecules, and microRNAs regulate neuronal migration and cancer cell metastasis. Polyunsaturated fatty acids and their products seem to modulate the expression of ephrin Bs and reelin and several adhesion molecules and microRNAs suggesting that bioactive lipids participate in neuronal regeneration and stem cell proliferation, migration, and cancer cell metastasis. Thus, there appears to be a close interaction among essential fatty acids, their bioactive products, and inflammation and cancer growth and its metastasis.

Studies showed that gamma-linolenic acid (GLA) and its derivatives have the potential to be anti-cancer molecules. In vitro, in vivo and limited clinical studies showed that GLA has selective tumoricidal action with little or no side effects. The mechanism of its action appears to be by inducing apoptosis of tumor cells by augmenting free radical generation only in the tumor cells but not normal cells. Intra-arterial injection of a lithium salt derivative of GLA demonstrated its ability to selectively occlude tumor-feeding vessels. Since GLA is an endogenous naturally occurring molecule and has no significant side effects, it calls for more studies to exploit its potential as a novel anti-cancer drug.

Purpose of Review: The onset of cancer anorexia and the accompanying neurological symptoms and signs involve the general influence of cytokines on the brain. Using methylcholanthrene to induce tumors in Fischer 344 rats, we measured various specific components of the cytokine-induced anorectic reaction, including: (1) IL-1beta system components (ligand, signaling receptor, receptor accessory proteins, and receptor antagonist); (2) TNF-alpha; (3) TGF-beta1; and (4) IFN-gamma in the tumor tissue, the liver and the brain., Recent Findings: The data show that IL-1beta, TNF-alpha and IFN-gamma messenger RNA were detected in the tumor tissue of anorectic tumor-bearing rats. In brain regions, anorexia is associated with the upregulation of IL-1beta and its receptor mRNA. All other mRNA remained unchanged in the brain regions examined., Summary: This suggests that IL-1beta and its receptor may play a significant role in this model of cancer-associated anorexia. In vivo, the characterization of cytokine components in the brain may provide data for potential pharmacological interventions to ameliorate the anorexia of disease.

gamma-Linolenic acid (GLA) is known to have selective tumoricidal action. In this study, the effect of lithium salt of GLA conjugated to iodized lymphographic oil (LGIOC) was injected intra-arterially close to the origin of tumor-feeding vessel(s) was studied. Four patients with stage 4 cancer disease (2 with hepatocellular carcinoma, 1 with giant cell tumor of the bone, and one with renal cell carcinoma), were selected for the study. Angiography, radiography and computed axial tomography were performed prior to and immediately after the injection of LGIOC and at periodic intervals. All four patients tolerated the treatment well. The most significant observation was the complete occlusion of the tumor-feeding vessels after LGIOC injection. Follow-up angiograms performed in all the patients showed occlusion of the tumor-feeding vessels is more or less permanent. A significant reduction in the size of the tumor was also observed in these patients. LGIOC showed occlusion of tumor-feeding vessels after infusion, and further studies are needed to confirm these preliminary results.

Tumour cell drug resistance is a major problem in cancer chemotherapy. Essential fatty acids have been shown to be cytotoxic to a variety of tumour cells in vitro. But, the effect of these fatty acids on tumour cell drug resistance has not been well characterized. Gamma-linolenic acid (GLA) of the n-6 series and eicosapentaenoic acid (EPA) of the n-3 series potentiated the cytotoxicity of anti-cancer drugs: vincristine, cis-platinum and doxorubicin on human cervical carcinoma (HeLa) cells in vitro. Alpha-linolenic acid (ALA), GLA, EPA and docosahexaenoic acid (DHA) enhanced the uptake of vincristine by HeLa cells. In addition, DHA, EPA, GLA and DGLA were found to be cytotoxic to both vincristine-sensitive (KB-3-1) and -resistant (KB-ChR-8-5) human cervical carcinoma cells in vitro. Pre-incubation of vincristine-resistant cells with sub-optimal doses of fatty acids enhanced the cytotoxic action of vincristine. GLA, DGLA, AA, EPA and DHA enhanced the uptake and inhibited the efflux of vincristine and thus, augmented the intracellular concentration of the anti-cancer drug(s). Fatty acid analysis of KB-3-1 and KB-ChR-8-5 cells showed that the latter contained low amounts of ALA, GLA, 22:5 n-3 and DHA in comparison to the vincristine-sensitive cells. The concentrations of GLA and DHA were increased 10-15 fold in the phospholipid, free fatty acid and ether lipid cellular lipid pools of GLA and DHA treated cells. These results coupled with the observation that various fatty acids can alter the activity of cell membrane bound enzymes such as sodium-potassium-ATPase and 5'-nucleotidase, levels of various anti-oxidants, p53 expression and the concentrations of protein kinase C suggest that essential fatty acids and their metabolites can reverse tumour cell drug-resistance at least in vitro.

Tumour necrosis factor/cachectin (TNF) is considered a primary mediator in the pathogenesis of injury, infection and inflammation and seems to be essential for host defense and tissue homeostasis. On the other hand, TNF can also cause septic shock, tissue injury and cachexia. There is a close interaction between TNF and other cytokines such as interferon, interleukin-1 and interleukin-2, and prostaglandins. TNF is responsible for the deleterious effects of endotoxaemia, and passive immunization against it substantially mitigates the lethal effect of endotoxin. It is also a potent pyrogen, causes bone resorption, activates neutrophil adherence and degranulation and phagocytosis, and ultimately participates in inflammatory diseases of the skin, gastrointestinal tract, joints, muscle and central nervous system and in neoplastic diseases.

Polyunsaturated fatty acids killed incubated human breast, lung and prostate cancer cells at concentrations which had no adverse effects on normal human fibroblasts or on normal animal cell lines. The most consistent and selective effects were obtained with fatty acids containing 3, 4 and 5 double bonds. When human cancer cells and normal human fibroblasts were co-cultured in the absence of polyunsaturated fatty acids, the malignant cells overgrew the normal ones. When eicosapentaenoic acid (EPA, 20:5n-3), gamma-linolenic acid (GLA, 18:3n-6) or arachidonic acid (AA, 20:4n-6) were added to the co-cultures, the normal cells outgrew the malignant ones. These observations suggest that treatment of malignancy with polyunsaturated fatty acids may have considerable potential while being associated with a high level of safety.

We have previously shown that cis-unsaturated fatty acids (c-UFAs) possess a selective tumoricidal action that can be blocked by antioxidants. This property of c-UFAs might be due to various factors, including increased uptake, unusual distribution, or an ability to alter free radical generation in tumor but not normal cells. 14C-labelled linoleic acid (LA) uptake was almost the same in normal and tumor cells, whereas that of 14C-labelled arachidonic acid (AA) and 14C-labelled eicosapentaenoic acid (EPA) in tumor cells was substantially less than in normal cells. Tumor cells incorporate major portions of the fatty acids in the ether lipid and phospholipid fractions, whereas normal cells incorporate the fatty acids primarily in the phospholipid fraction. LA, AA, and EPA augmented nitroblue tetrazolium reduction, an indication of free radical generation, selectively in the tumor cells. These results suggest that there are significant differences between normal and tumor cells in fatty acid uptake and distribution, and in the ability of fatty acids to generate free radicals.