The reversibility of cancer: the relevance of cyclic AMP, calcium, essential fatty acids and prostaglandin E1

Unsaturated Fatty Acid Synthesis Is Associated with Worse Survival and Is Differentially Regulated by MYCN and Tumor Suppressor microRNAs in Neuroblastoma

MYCN amplification (MNA) and disruption of tumor suppressor microRNA (TSmiR) function are key drivers of poor outcomes in neuroblastoma (NB). While MYCN and TSmiRs regulate glucose metabolism, their role in de novo fatty acid synthesis (FAS) and unsaturated FAS (UFAS) remains poorly understood. Here, we show that FAS and UFAS (U/FAS) genes FASN, ELOVL6, SCD, FADS2, and FADS1 are upregulated in high-risk (HR) NB and that their expression is associated with lower overall survival. RNA-Seq analysis of human NB cell lines revealed parallel U/FAS gene expression patterns. Consistent with this, we found that NB-related TSmiRs were predicted to target these genes extensively. We further observed that both MYC and MYCN upregulated U/FAS pathway genes while suppressing TSmiR host gene expression, suggesting a possible U/FAS regulatory network between MYCN and TSmiRs in NB. NB cells are high in de novo synthesized omega 9 (ω9) unsaturated fatty acids and low in both ω6 and ω3, suggesting a means for NB to limit cell-autonomous immune stimulation and reactive oxygen species (ROS)-driven apoptosis from ω6 and ω3 unsaturated fatty acid derivatives, respectively. We propose a model in which MYCN and TSmiRs regulate U/FAS and play an important role in NB pathology, with implications for other MYC family-driven cancers.

FADS2 function at the major cancer hotspot 11q13 locus alters fatty acid metabolism in cancer

Dysregulation of fatty acid metabolism and de novo lipogenesis is a key driver of several cancer types through highly unsaturated fatty acid (HUFA) signaling precursors such as arachidonic acid. The human chromosome 11q13 locus has long been established as the most frequently amplified in a variety of human cancers. The fatty acid desaturase genes (FADS1, FADS2 and FADS3) responsible for HUFA biosynthesis localize to the 11q12-13.1 region. FADS2 activity is promiscuous, catalyzing biosynthesis of several unsaturated fatty acids by Δ6, Δ8, and Δ4 desaturation. Our main aim here is to review known and putative consequences of FADS2 dysregulation due to effects on the 11q13 locus potentially driving various cancer types. FADS2 silencing causes synthesis of sciadonic acid (5Z,11Z,14Z-20:3) in MCF7 cells and breast cancer in vivo. 5Z,11Z,14Z-20:3 is structurally identical to arachidonic acid (5Z,8Z,11Z,14Z-20:4) except it lacks the internal Δ8 double bond required for prostaglandin and leukotriene synthesis, among other eicosanoids. Palmitic acid has substrate specificity for both SCD and FADS2. Melanoma, prostate, liver and lung cancer cells insensitive to SCD inhibition show increased FADS2 activity and sapienic acid biosynthesis. Elevated serum mead acid levels found in hepatocellular carcinoma patients suggest an unsatisfied demand for arachidonic acid. FADS2 circular RNAs are at high levels in colorectal and lung cancer tissues. FADS2 circular RNAs are associated with shorter overall survival in colorectal cancer patients. The evidence thusfar supports an effort for future research on the role of FADS2 as a tumor suppressor in a range of neoplastic disorders.

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.

Interference of phosphatidylcholines with in-vitro cell proliferation - no flock without black sheep

According to early experiments with natural extracts, phosphatidylcholines (PCs) are widely considered essentially non-toxic. In addition to these physiological mixed-chain PCs, many different synthetic diacyl-PCs are currently available, but they have never been systematically evaluated for any interference with cell proliferation. We thus investigated the cell proliferation of several cell lines in the presence of various liposomes consisting of a single PC component and cholesterol. Most of the PCs investigated did not interfere with cell proliferation, supporting the notion that most PCs are safe excipients. Significant IC50 values below 0.5mM were detected for PC(12:0/12:0), PC(14:1/14:1)trans and all diacyl-PCs containing two polyunsaturated fatty acids (PUFAs). The ω-3 PC(22:6/22:6) was the most toxic PC assessed, revealing IC50 values below 100 μM, but no rule concerning ω-3/6 configuration or acyl chain length could be observed. Physiological mixed-chain PCs containing PUFAs were much less toxic than respective non-physiological diacyl-PCs. All trans fatty acids in diacyl-PCs interfered more with proliferation than their respective cis-configured counterparts. Depending on the concentration, those diacyl-PCs not only inhibited proliferation but also induced cell death. Unlike the non-toxic PCs usually used for liposomal drug delivery, the elucidated diacyl-PCs may be worthy of further examination to eventually construct a toxic shell for toxic drugs, thereby enhancing anticancer drug delivery via lipid particles.

Effect of dietary GLA+/-tamoxifen on the growth, ER expression and fatty acid profile of ER positive human breast cancer xenografts

Gamma linolenic acid (GLA) possesses a number of selective anti-tumour properties including modulation of steroid receptor structure and function. We have investigated the effect of dietary GLA on the growth, oestrogen receptor (ER) expression and fatty acid profile of ER+ve human breast cancer xenografts. Experimental diets A, B, C, D were commenced after subcutaneous implantation of 40 female nude mice with the MCF-7 B1M cell line (Group A = control diet: B = control diet + GLA supplement: C = control diet + tamoxifen: D = control diet + GLA + tamoxifen; 10 mice/group). The mice were terminated when tumour cross-sectional area reached 250 mm(2). ER H-scores were assessed by immunohistochemical assay and fatty acid profiles by gas-liquid chromatography of termination tumour samples. Groups C and D displayed significantly slower tumour growth (p =.0002, p =.0006) with trend for slower growth in B (p =.065) compared to control Group A. ER was significantly reduced in all groups compared to A (p <.0001) with Group D (combined therapy) displaying markedly lower ER expression than with either therapy alone (p =.0002). There were significantly raised levels of tumour GLA and metabolites in the two groups (B and D) receiving GLA (p <.0001). This xenograft model of ER+ve breast cancer has demonstrated significantly lower tumour ER expression in those groups receiving GLA, an effect which appears to be additive to the reduced ER expression resulting from tamoxifen alone. The effects of GLA on ER function and the possibility of synergistic inhibitory action of GLA with tamoxifen via enhanced down-regulation of the ER pathway require further investigation.

Epidermal growth factor and glucocorticoid effects on blood prostaglandin E2 level in DENA-induced carcinogenesis

This paper describes results on carcinogenesis in rats induced with diethylnitrosamine (DENA; 280 mg/kg single dose, i.p.). After inducing chemical carcinogenesis, the animals were treated with different compounds that affect cell proliferation and the effects on the blood prostaglandin E2 (PGE2) levels were observed. These compounds were epidermal growth factor (EGF, 10 micrograms/kg/24 h i.p., 7 days) and dexamethasone (4 mg/kg/24 h i.p., 7 days). The blood PGE2 levels of rats were measured by RIA (Radioimmunoassay). The blood PGE2 levels increased significantly following DENA and EGF administrations alone or together. Dexamethasone administration decreased the blood PGE2 levels. In conclusion the data show that the increase in the plasma PGE2 level by DENA treatment was enhanced by EGF but opposed by dexamethasone. This suggests that EGF may be effective as a promoter in chemical carcinogenesis.

The role of adenylate cyclase, cAMP and PGE2 in the in vitro growth regulation of murine melanoma cells by vitamin E

Previous studies have shown that vitamin E supplementation inhibits murine melanoma cell growth in vitro. In this study, malignant murine melanoma (BL6) and non-malignant monkey kidney (LLCMK) cells were supplemented with 1-10 micrograms/ml D-alpha-tocopherol acid succinate (vitamin E succinate). The effect of vitamin E succinate supplementation on growth as well as the levels of adenylate cyclase activity, prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP) were determined in these cells. Results from these studies indicated a significant inhibition of BL6 cell growth at 5 (P < 0.025), 7 and 10 micrograms/ml (P < 0.001) vitamin E succinate supplementation, while LLCMK cells showed no significant increase or decrease in growth following vitamin E succinate supplementation. BL6 cells supplemented with 7 and 10 micrograms/ml vitamin E succinate showed a marked increase in PGE2 levels, with a significant increase (P < 0.025) occurring at 10 micrograms/ml. Adenylate cyclase activity in BL6 cells was also significantly increased at vitamin E succinate concentrations of 7 (P < 0.05) and 10 micrograms/ml (P < 0.05), respectively, and supplementation of these cells with 5 (P < 0.05), 7 and 10 micrograms/ml (P < 0.001) vitamin E succinate resulted in a significant increase in the levels of cAMP, while LLCMK cells showed no significant increase or decrease in PGE2, adenylate cyclase activity or cAMP levels over the vitamin concentrations tested.

Effects of gamma-linolenic and dihomo-gamma-linolenic acids on 7,12-dimethylbenz(alpha)anthracene-induced mammary tumors in rats

The effects of pure gamma-linolenic acid (GLA; C18:3, n-6) and dihomo-gamma-linolenic acid (DGLA; C20:3, n-6) were investigated in 7,12-dimethylbenz(alpha)anthracene (DMBA) (10 mg/rat)-induced mammary tumors in Sprague-Dawley rats. 0.15 g of GLA, DGLA, or corn oil (CO) were administered (two times per week) by oral intubation, for 12 weeks to rats maintained on a 5% (w/w) CO diet. Tumor incidence, tumor multiplicity, and percent of tumor-bearing rats were highest in the CO group. Tumor multiplicity was significantly reduced in the GLA group (p = 0.015). Feeding of GLA and DGLA resulted in significant alterations in levels of these fatty acids in phospholipids of mammary tissue, thymus, colon, liver, stomach, and ovary. These results suggest that GLA may have a small, but significant, inhibitory effect on the development of DMBA-induced mammary tumors in rats.

In vitro effects of prostaglandin E1 and indomethacin on mitomycin C-induced sister-chromatid exchanges in mitogen-stimulated human lymphocytes

In this study, the individual and combined effects of prostaglandin E1 (PGE1) and Indomethacin on mitomycin C (MMC)-induced SCEs in human lymphocytes was investigated in vitro. All MMC-treated cultures showed a great increase of SCEs (approximately two-fold), indicating its ability to induce mutations. SCE data showed that MMC-induced SCEs were reduced significantly in the presence of PGE1 in pooled analysis of six experiments (60.55% reduction of SCEs at 10(-6) M, 34.13% reduction of SCEs at 10(-9) M). In contrast the presence of indomethacin in the medium during MMC treatment of cells failed to show a significant reduction of SCEs in pooled analysis (21.17%). However, individual analyses revealed only two of six donors with a significant SCE response. Thus, the findings suggest that PGE1 can modify the DNA damaging effect of carcinogens and thereby may prevent the initiation of the carcinogenic process.

Effect of diethylnitrosamine on prostaglandin E and lipid peroxidation levels in rat's liver, lung and renal tissue

We have investigated the generation of a prooxidant state and effect on prostaglandin E (PGE) levels after administration of diethylnitrosamine (DENA) to rats. Lipid peroxides were assayed by monitoring thiobarbituric acid (TBA) a reactive material. PGE--like activity was assayed by using bioassay procedure. Our results demonstrate that increased lipid peroxide and decreased PGE levels were found in a dose dependent manner in DENA injected groups when compared to control groups. According to these findings, it is suggested that there is a negative correlation between carcinogenic DENA induced lipid peroxidation and PGE in rat's liver, lung, and renal tissue.

Effects of eicosapentaenoic acid, gamma-linolenic acid and prostaglandin E1 on three human colon carcinoma cell lines

Several studies have demonstrated that certain essential fatty acids present a specific cytotoxicity for tumor cells. However, no investigation of this type has been performed on human colon cancer cells to date. This study investigated the effect of gamma-linolenic acid (GLA), eicosapentaenoic acid (EPA) and prostaglandin (PG) E1 on the proliferation and metabolism of three human colon cancer cell lines: HT 29, HRT 18, and CACO 2. GLA, EPA and PGE1 all inhibited the proliferation of the three cell lines, but with a decreasing gradient of sensitivity: HRT 18 > HT 29 > CACO 2, and with different IC50 values. PGE1 was markedly less effective than the other two. GLA and EPA increased lipid peroxidation and membrane fluidity in a dose-dependent manner. The presence of indomethacin did not modify the effects of GLA and EPA. In addition, PGE1 had little effect on membrane fluidity and lipid peroxidation. The antitumoral effect thus does not appear to be mediated by PGE1. Addition of vitamin E decreased the effects of GLA and EPA, which supports the hypothesis of direct action by these fatty acids. In conclusion, while EPA and GLA have an antitumoral effect in vitro, their effect on primary cultures of normal human colon cells must be investigated to determine whether this effect is specific to tumoral cells, as has been observed for other cell types.

A proposed mechanism of anticancer activity of indomethacin

The exact mechanism of anticancer activity of indomethacin still remains unclear. In view of the gathered observations and ideas, I hypothesize that the effect of indomethacin may be related--at least in certain cases--to its antagonism to gastrin/cholecystokinin family of peptides and/or to its agonistic activity to thromboxane A2 and melatonin. Future experiments in this direction are required.

Effects of increasing dietary linoleic acid on phospholipid fatty acid composition and eicosanoid production in leucocytes and gill cells of Atlantic salmon (Salmo salar)

Diets containing linoleic acid at 10, 25 and 45% of total dietary fatty acids were fed to three groups of post-smolt Atlantic salmon (Salmo salar) for 18 weeks. Incorporation of linoleic acid into membrane phospholipids of leucocytes and gills increased in response to dietary intake. In general, there was an increase in arachidonic acid and a decrease in eicosapentaenoic acid in the individual phospholipids of both cell types in response to increasing dietary linoleic acid. These changes in eicosanoid precursors were reflected in significantly increased plasma concentrations of 6-keto-PGF1 alpha and TXB2 in salmon given the highest dietary linoleic acid. In whole blood stimulated with the calcium ionophore A23187, LTB4, 12-HETE and TXB2 were significantly increased and 12-HEPE significantly decreased in response to increasing dietary linoleic acid. In isolated gill cells stimulated with A23187, 12-HEPE, 12-HETE, 14-HDHE and TXB2 were all decreased in response to increasing dietary linoleic acid, although the ratio of 12-HEPE/12-HETE was also decreased.

To wall off neoplasms with more viscous extracellular matrix

Normal inflammatory and immune mechanisms would destroy most neoplasms if the neoplasm did not alter its immediate environment to weaken the host defenses. Based on factors that seem to increase extracellular matrix viscosity, methods of enhancing host resistance in the vicinity of the tumor are suggested by the author. This includes adjuvant therapy, pyridoxine antagonist, cytokines, beta carotene, retinoids, vitamin C, iodides, bromides, and pellagragenic substances. Hyperthermia may also have an effect.

The effect of gamma-linolenic acid and zinc supplementation on the growth of normal and tumour cells in vitro

The effects of zinc, gamma-linolenic acid (GLA) and zinc combined and GLA supplementations on the growth of a benign monkey kidney, cell line (LLCMK) and a malignant tumour murine melanoma, cell line (BL-6) cells in vitro were studied. Cell growth was indicated by both cell counts and 3H-thymidine incorporation into DNA. The addition of zinc to the cells resulted in a general trend of overall reduction in the growth of tumour cells but not in the normal cells. The addition of GLA at high concentrations resulted in a general decrease in cell growth of both the benign and malignant tumour cells while the addition of lower concentrations of GLA had less effect. The combined effect of supplementary zinc and GLA resulted in an inhibitory effect on the growth of the malignant cells while a less and variable effect on the non-malignant cells was found. Some interaction between zinc and GLA in reducing tumour cell growth is suggested by the results.

Possible involvement of delta-6-desaturase in control of melanoma growth by gamma-linolenic acid

This study examined the effects of linoleic acid (LA) and gamma-linolenic acid (GLA) on BL6 melanoma growth in cell culture and of safflower oil (SFO) which contains LA and evening primrose oil (EPO) which contains GLA, on melanoma growth when grown in mice. The delta-6-desaturase activity of the melanoma cells in the two systems was also examined and an attempt made to relate the activity of the enzyme to the effects of GLA on cell and tumour growth. LA and GLA were found to be equipotent in inhibiting growth of the in vitro cultured BL6 cells which were found to contain an appreciable level of delta-6-desaturase activity. EPO was however found to be a more potent promoter of in vivo melanoma growth in mice than SFO. Melanomas grown in mice were found to lack delta-6-desaturase activity suggesting that the EPO diet, by providing GLA, was able to compensate for the loss of enzyme activity in the melanomas. The possibility that melanomas in mice have a requirement for GLA for growth while in in vitro cultured cells excess GLA inhibits the growth of the cells through an increase in lipid peroxidation is discussed.

Abnormalities of essential fatty acid distribution in the plasma phospholipids of patients with bladder cancer

We have examined the composition of the essential fatty acids in the plasma phospholipid fractions of 98 patients with histologically proven bladder cancer. These patients were attending hospital for regular follow-up by check cystoscopy. Patients were divided into two groups, depending on the cystoscopic findings, of either active (tumour recurrence seen) or inactive (no evidence of tumour recurrence) disease. Compared with a normal population, the plasma levels of most of the fatty acids, including arachidonic acid, were significantly lower in the 98 cancer patients (P less than 0.001, t-test). We were unable, however, to demonstrate any significant differences (Mann-Whitney U-test) between the active and inactive disease groups. Plasma levels of the essential fatty acids are abnormal in patients with bladder cancer; they do not help, however, to distinguish those patients with active disease from those with inactive disease. This may arise because the deficit in essential fatty acids we have demonstrated is a predisposing factor for the development of bladder cancer rather than a metabolic consequence of the tumour. Further studies are needed to establish the possible clinical role of measurement of essential fatty acids in patients with bladder carcinoma.

Eicosanoid synthesis and ornithine decarboxylase activity in mammary tumors of rats fed varying levels and types of N-3 and/or N-6 fatty acids

Virgin female Sprague-Dawley rats (50 days of age) were administered a single intragastric 10 mg dose of 7,12-dimethylbenz(a) anthracene (DMBA). Three weeks later they were placed on diets containing either 20% corn oil (CO), 20% primrose oil (PO), 20% black currant seed oil (BCO), 20% borage oil (BO), 15% menhaden oil plus 5% corn oil (15% MO + 5% CO), 10% menhaden oil plus 10% corn oil (10% MO + 10% CO), 5% menhaden oil plus 15% corn oil (5% MO + 15% CO) or 10% menhaden oil plus 10% borage oil (10% MO + 10% BO). Incidences of mammary tumors at 16 weeks post-DMBA were 80% in rats fed the CO diet, 84% in rats fed PO diet, 67% in rats fed BCO diet, 88% in rats fed BO diet, 60% in rats fed 15% MO + 5% CO diet, 67% in rats fed 10% MO + 10% CO diet, 83% in rats fed 5% MO + 15% CO diet, and 92% in rats fed 10% MO + 10% BO diet. Tumor multiplicity was lowest in PO-fed rats and highest in BO-fed rats. The tumor burden per tumor-bearing rat was lowest in rats fed the 15% MO + 5% CO, and 10% MO + 10% CO, diets and highest in those fed 20% BCO diet. Although body weight at 16 weeks post DMBA was not significantly different among the dietary groups, food intake was significantly greater in rats fed a diet containing 20% BO, or 5% MO + 15% CO.(ABSTRACT TRUNCATED AT 250 WORDS)

Defective generalized extracellular matrix in the neoplasm bearing host: decreased inflammation, immunity and resistance

Neoplasms have extensive qualitative and quantitative changes in their extracellular matrix. Lytic factors from neoplasms breakdown extracellular matrix of the areas adjacent to the neoplasms and fibroblasts in these areas produce increased extracellular matrix. Some of the extracellular matrix fractions are normally present in serum. Multiple fractions derived from extracellular matrix are present in the serum of tumor patients. Tumor patients often have decreased early cellular inflammation and immunity. These reactions depend on a normal extracellular matrix. A number of known facts about the tumor bearing host can be explained by the concept that the host's generalized extracellular matrix is altered by circulating fractions of extracellular matrix. These could be qualitative or quantitative defects as well as an abundance of depolymerized fractions. The beneficial effects of cytokines, streptococcal infections and pyridoxine deficiency on tumors can be explained by this concept.

Serum tumor markers of head and neck cancer: current status

The serum level of a variety of substances shows significant changes in head and neck cancer patients. Such substances are collectively called biochemical tumor markers. To date, most markers lack a high degree of specificity and sensitivity. However, serial measurement of markers showing elevated pretreatment levels may help in monitoring response to therapy. Other potential uses of tumor markers include earlier detection of recurrence and/or metastasis, and possible prediction of prognosis. Measurement of more than one marker seems to enhance the diagnostic accuracy of the test. Some markers show significant correlations with various immune parameters in head and neck cancer patients and may have a possible role in potentiating the immunodepressed status of such patients. A review of currently reported tumor markers in head and neck cancer showing their nature, sources, uses, and limitations is presented.

Pyridoxine deficiency and antagonism produce increased ground substance viscosity with resulting seborrheic dermatitis and increased tumor resistance

Pyridoxine deficiency and 4'-deoxypyridoxine produce acrodynia in rats and seborrheic dermatitis in man. They also produce tumor inhibition in man and animals. Pyridoxine is extensively involved in metabolism and its relationship to the inhibitor 4'-deoxypyridoxine is complex. Pyridoxine deficiency and antagonism increases ground substance viscosity. This increase the inflammatory reactivity of the skin to produce acrodynia in rats and seborrheic dermatitis in man. The increase in ground substance viscosity would explain the increased resistance to tumors in man and animals. Pyridoxine is important in protein metabolism. The protein moiety of glycosaminoglycans in ground substance is small but plays a major role in tissue viscosity. Pyridoxine deficiency or antagonism by itself does not offer a definitive answer for tumors. Combined with substances that stimulate fibroblast or glycosaminoglycans production it may have a significant additive effect.

On the nature of growth and new growth based on experiments designed to reveal a structure and function for laboratory space. Part III. Vorticeal behaviour. Dielectrics and matter responsiveness to fields. The primacy of pressure

This final paper in a series of three continues the discussion on experiments reported in the first which suggested a structure and function for laboratory space. The discussion is grouped under three heads. First a continuation of the discussion of vorticeal properties emphasises the ubiquity of non-observable vorticeal streets (filaments) at site of growth be this biological or hydrodynamic. Vorticeal patterns in pairs of streets can lead to stable or unstable behaviour. Stability of the pattern may underlie that filament subtending new growth in contrast to the instability leading to differentiation in growth manifest from unstable filaments. Rational treatment of the former would suggest exhibition of instability and this may underlie regimes as disparate as Lakhovsky's non-linear oscillators, Coley's bacterial digests and interferon used for cancer therapy. Secondly, study of dielectric properties of biomatter could be used to support the generalisation reached from vorticeal behaviour that the most ordered matter (high permittivity) is associated with growth and embryonic properties and the least ordered with differentiation and maturity. Finally those experiments are referred which showed a concurrence of atmospheric pressure and electrical effects at the remote site during action at a distance. Reasons making use of quantum field theory tenets are advanced for viewing pressure as a primary and the electrical effects as a secondary response to pressure in the non observable world.

The role of prostaglandins in the inhibition of cultured carcinoma cell growth produced by gamma-linolenic acid

The growth of the cultured human breast carcinoma cell line NUB 1 as well as that of other cultured malignant cells has been shown to be inhibited by addition of gamma-linolenic acid (GLA) to the culture medium. It has previously been suggested that these findings may be attributed to correction of a GLA deficiency in malignant cells, with supplementation of this fatty acid leading to increased prostaglandin (PG) production and consequent growth inhibition. To test this hypothesis the effect of 50 micrograms/ml concentrations of GLA and its sequential metabolite dihomo-gamma-linolenic acid (DGLA) and cell growth, morphology and prostaglandin (PGE and PGF) production by NUB 1 cells was investigated. GLA increased PGE and PGF production, inhibited cell growth and caused accumulation of lipid containing cytoplasmic granules. While treatment with DGLA increased PG production to a significantly greater extent than GLA administration it had no apparent effect on cell growth of morphology and did not inhibit cell growth. These findings suggest that some action other than the ability to increase PG production may be responsible for the inhibitory effects produced by GLA in malignant cells.

Polyunsaturated fatty acids stimulate superoxide formation in tumor cells: a mechanism for specific cytotoxicity and a model for tumor necrosis factor?

Some neoplastic cell lines are readily killed when incubated in the presence of polyunsaturated fatty acids (PUFA). In an attempt to elucidate this phenomenon, we studied PUFA-driven superoxide (O2-) production by cultured NS-1 cells (murine lymphoid tumor cells). We find: (1) Even in the absence of added PUFA, NS-1 cells generate O2- (i.e., reduce nitroblue tetrazolium). (2) addition of PUFA increases O2- by greater than 50%. (3) Artificial loading of NS-1 cells with liposome encapsulated superoxide dismutase prevents the majority of spontaneous and PUFA-driven NBT reduction. We conclude that PUFA drives O2- generation by tumor cells, that this generation is largely intracellular, and that this phenomenon may help explain toxicity of PUFA for tumor cells.

Effects of polyunsaturated fatty acids and of their oxidation products on cell survival

The stimulatory, cytostatic and cytotoxic effects of polyunsaturated fatty acids, prostaglandins, thromboxanes, hydroperoxy fatty acids, hydroxy fatty acids and leukotrienes on normal and tumor cells are described. Their effects are related to the ability of the cells to undergo lipid peroxidation. The significance of controlled peroxidation of selected polyunsaturated fatty acids in the control of tumor development is examined. It is suggested that selected polyunsaturated fatty acids if used at appropriate concentrations may have a protective role against cancer development by inducing and/or mediating cytotoxic reactions in malignant cells directly or indirectly through the intermediacy of immune cells.

Antitumor effect of gamma-linolenic acid on cultured human neuroblastoma cells

gamma-linolenic acid (GLA) was found to suppress the cell growth of 4 human neuroblastoma cell lines. GOTO was the most sensitive, followed by SK-N-DZ and NKP, while NCG was much less sensitive to GLA. In terms of GLA cytotoxicity, neither cyclo-oxygenase inhibitors nor a lipoxygenase inhibitor showed any effect. On the other hand, 4 antioxidants (Coenzyme Q, (D) alpha-tocopherol, (DL) alpha-tocopherol, butylated hydroxytoluene) reduced the growth inhibitory effect of GLA, but not in proportion to the decrease of GLA-stimulated lipid peroxidation. Accordingly, prostaglandins and leukotrienes probably do not play a role, and lipid peroxide may only be partly involved in the GLA effect.

A deficiency in dietary gamma-linolenic and/or eicosapentaenoic acids may determine individual susceptibility to AIDS

We hypothesize that a relative deficiency in gamma-linolenic and eicosapentaenoic acids and in their derivatives may contribute to the development of AIDS. These polyunsaturated fatty acids (PUFAs) may be the source of natural endogenous agents against AIDS by preventing the spread of viral infection due to their ability to destroy enveloped viruses, by controlling cancer development either directly due to their cytostatic and cytotoxic effects on cancer cells or indirectly by modulating the immune response and by protecting from genetic damage. Supplementation of these dietary PUFAs in the prevention, and possibly in the treatment of AIDS, is considered.

An antithrombotic role for nutritional antioxidants: implications for tumor metastasis and other pathologies

Nutritional antioxidants support prostacyclin synthesis by preventing lipid hydroperoxide-mediated inhibition of prostacyclin synthetase. Recent preliminary clinical studies indicate that supplementary antioxidants exert antithrombotic effects in vivo that are most likely attributable to enhanced prostacyclin production. Optimal antioxidant nutrition may thus have preventive and therapeutic value for disorders in which inappropriate platelet aggregation plays an etiologic role, including MI, stroke, atherogenesis, pre-eclampsia, and the vascular complications of diabetes. In light of evidence that platelet aggregation encourages the implantation of hematogenous tumor metastases, supplemental antioxidants should also impede tumor dissemination--an effect which will be complemented by the immunostimulant actions of these nutrients. By exerting anticarcinogenic, immunostimulant and anti-metastatic effects, nutritional antioxidants should act to inhibit neoplasia at each stage of its development.

Regression of lymphosarcoma by treatment with acetylsalicylic acid in rats

Increased synthesis of prostaglandins (PGs) may be an important promoting factor in the development of lymphosarcoma. Thus, inhibition of PG synthesis may represent a logical way of controlling the growth of lymphosarcomatous cells. In order to verify this hypothesis, two groups of rats with lymphosarcoma have been used: the test-group received acetyl salicylic acid (54 mg/animal/day) and the control-group received the same quantity of physiological saline solution. After 4 days of treatment, the lymph nodes stopped growing in the test-group. Microscopic and electron microscopic examinations of lymph node sections were carried out after 11 days of treatment. These showed for the test-group the disappearance of the characteristics of malignancy.

Effects of gamma-linolenic acid, dihomo-gamma-linolenic acid and ethanol on cultured human mammary carcinoma cells

A number of fatty acids have been shown to inhibit the growth of malignant cells in vitro. In particular, gamma-linolenic acid (GLA) has been proposed to act as a precursor for the production of prostanoids especially prostaglandin E1 (PGE1). To test this hypothesis, the effects of GLA on cultured human breast carcinoma cells were compared with those of dihomo-gamma-linolenic acid (DGLA) the metabolite of GLA and the immediate precursor of PGE1. The influence of ethanol (which has been shown to enhance conversion of DGLA to PGE1) on the actions of each of the fatty acids was also investigated. In contrast to the inhibitory effects observed with all concentrations of GLA cell growth was promoted by the presence of 50 micrograms DGLA. Ethanol reduced the action of both GLA and DGLA possibly due to some physicochemical reaction between the alcohol and the fatty acids. The fact that the actions of GLA were not mimicked by DGLA which is the next step towards PG production casts doubt upon the role of PGE1 as mediator of the effects which have been observed with GLA in malignant cells.

Selective killing of human cancer cells by polyunsaturated fatty acids

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.

The response of human carcinoma cell lines to gamma-linolenic acid with special reference to the effects of agents which influence prostaglandin and thromboxane synthesis

Recently, addition of gamma linolenic acid (GLA) which is a precursor of prostaglandin E1 (PGE1) to cell cultures, has been shown to inhibit growth of various carcinoma cells (1,2,3,4). These findings are consistent with Horrobin's proposal that some of the metabolic abnormalities of malignant cells may be due to deficiencies of certain prostanoids. To determine whether the observed effects of GLA are in fact mediated by increasing levels of its metabolites, this study investigated the influence of various inhibitors and stimulants of prostaglandin (PG) synthesis on the effects of GLA on carcinoma cells in vitro. Most of the agents used (aspirin, imidazole, lithium carbonate and ascorbic acid) produced results consistent with the idea that elevation of levels of thromboxane A2 (TxA2) and/or PGE1 may be important as regards the actions of GLA. In sharp contrast was the result obtained with indomethacin. This drug, which could be expected to block conversion of GLA to PGE1 and therefore protect cells against the effects of GLA, actually exaggerated the effects of this fatty acid, thereby causing cell death and desquamation.

Integration of allogeneic lymphocyte immunotherapy with short-course chemotherapy and hypoenergic hyperthermia: a "triple-threat" treatment for disseminated cancer

A strategy for treatment of disseminated cancer is proposed which unites short-course chemotherapy, local hyperthermia, and allogeneic lymphocyte immunotherapy, designed and timed so as to optimize their synergistic interactions. Short-course chemotherapy potentiates allogeneic lymphocyte immunotherapy, and in turn is potentiated by subsequent courses of local hyperthermia. Response to hyperthermia can be enhanced by measures which selectively inhibit tumor blood flow, impair tumor energy metabolism, and produce tumor acidification; these include induction of prolonged hyperglycemia, and administration of selectively activated "hypoenergic" agents which inhibit or uncouple tumor respiration. It is anticipated that these methods will enable a significant advance in the control of metastasized solid tumors.

Rationale for a novel immunotherapy of cancer with allogeneic lymphocyte infusion

A simple method of cancer immunotherapy has been developed which achieves marked objective response in 20-30% of patients with disseminated disease. Each course consists of a low dose of chemotherapy followed two days later by intravenous infusion of allogeneic lymphocytes. Courses are repeated on a monthly basis as needed. The function of the chemotherapy--too mild to significantly influence tumor growth directly--appears to be depletion of suppressor T cells, which sensitizes the patient to the immunostimulant action ("allogeneic effect") of the subsequently infused lymphocytes. The rationale for this method is discussed in the context of a review of past attempts at lymphocyte immunotherapy. We are now attempting to improve response rates by combatting anergy with nutritional immunopotentiators, and by preventing prostaglandin-mediated or -dependent immunosuppression with prostaglandin synthetase inhibition. By understanding and counteracting the various specific and general means by which a growing tumor induces host tolerance, it should prove possible to achieve immune-mediated tumor regression in a high proportion of patients. Best results may be seen when allogeneic lymphocyte therapy is initiated at an earlier stage of the disease, and is used in conjunction with surgery, radiotherapy, short-course intensive chemotherapy, or hyperthermia-based methods.

Prostaglandins and mutagenesis: prevention and/or reversibility of genetic damage induced by benzo (a) pyrene in the bone marrow cells of mice by prostaglandin E1

Prostaglandin E1 and thromboxane A2 (PGE1 and TXA2) have been proposed to bind to DNA, regulate gene action and prevent mutagenesis. Benzo (a) pyrene (BP) is a known mutagen and tumor promotor. BP-induced damage to the bone marrow cells of mice was prevented and/or reversed by PGE1 and by colchicine, an agent which may enhance PGE1 synthesis and TXA2 synthesis or action. PGF2 alpha did not have any action. Imidazole, a selective TXA2 synthesis inhibitor, enhanced the mutagenic action of benzo (a) pyrene. These results lend support to the concept that an altered PG system may have a role in the pathogenesis of mutagenesis and carcinogenesis.

Some effects of the essential fatty acids linoleic acid and alpha-linolenic acid and of their metabolites gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and of prostaglandins A1 and E1 on the proliferation of human osteogenic sarcoma cells in culture

Gamma-linolenic acid has been shown to suppress the rate of proliferation of a number of malignant cell lines in culture. To test the proposal that this was a specific prostaglandin 1- or 2-series effect, 379 batches of MG63 human osteogenic sarcoma cells were seeded in Greiner flasks and cultured in media supplemented with a range of unsaturated fatty acids and prostaglandins. The monounsaturated fatty acid oleic acid enhanced the rate of cancer cell proliferation. The polyunsaturated fatty acids linoleic acid, gamma-linolenic acid, arachidonic acid, alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid, as well as prostaglandins E1 and A1 suppressed the rate of cell proliferation. Total suppression of colony forming and cell proliferation occurred at high levels of polyunsaturated fatty acid supplementation. In addition gamma-linolenic in the form of evening primrose seed oil and vitamin C has been given to 6 patients with histologically diagnosed primary liver cell cancer. Some clinical improvement and reduction in tumor size occurred in 3 cases. One patient has shown remarkable improvement in reduction of liver and tumor size on the CAT scan and reduction of the serum alkaline phosphatase from 2830 to 295 units and gamma-glutamyl transaminase from 274 to 82 units. Thus preliminary clinical results suggest that gamma-linolenic acid may be effective in the management of human cancer patients and further trials should be conducted. However, the cell culture results suggest that although the essential fatty acids suppress proliferation, eicosanoids of all 3 series may be involved. The proliferation suppressive effect of docosahexaenoic acid suggests that other aspects than only eicosanoid activity may also be important in the suppression of cancer cell proliferation.

Prostaglandins and mutagenesis: modification of phenytoin induced genetic damage by prostaglandins in lymphocyte cultures

Diphenylhydantoin (DPH) is known to cause genetic damage both in vivo and in vitro. We investigated the effect of prostaglandin E1, E2 and F2 alpha on DPH induced chromosomal aberrations in lymphocyte cultures in vitro. Prostaglandin E1 prevented and/or reversed DPH induced chromosomal aberrations, whereas PGE2 and PGF2 alpha were without inhibitory action. In fact, PGE2 and PGF2 alpha themselves induced genetic damage comparable to that of DPH, suggesting that PGE2 and PGF2 alpha are mutagenic in nature whereas PGE1 has anti-mutagenic properties. These results are consistent with the hypothesis that an altered prostaglandin system could be involved in mutagenesis.

Cancer: a simple metabolic disease?

Recent studies on the effects of the essential fatty acid metabolic intermediate, gamma-linolenic acid, on the growth of cancer cells in culture and on induced mammary cancer tumours in rats, strongly suggest that the metabolic defect in the cancer cells studied is simply a metabolic block involving the enzyme delta-6-desaturase. The latter enzyme is responsible for the conversion of linoleic acid to gamma-linolenic acid. These observations would suggest that cancer in the cell lines studied could be a relatively simple metabolic disease.

Prostaglandins in breast cancer: relationship to disease stage and hormone status

Tissue prostaglandin (PG) content and production by human breast cancers were measured in 24 human mammary carcinoma specimens. The 5 compounds studied were PGE1, PGE2, PGF2 alpha, 6-keto-PGF1 alpha, and TXB2. The tissue content of all 5 compounds was higher in neoplastic tissue in comparison with the paired noncancerous breast tissue. However, microsomal PG synthetase activity in vitro in noncancerous and neoplastic breast tissue was comparable. Increased thromboxane formation was associated with three clinical variables--tumour size, axillary lymph node metastases and distant metastasis. A lesion negative for either oestrogen or progesterone receptor content tended to produce more TXB2 but lower PGE2 and 6-keto-PGF1 alpha. Results obtained in this pilot study may provide clues as to what direction future larger studies could take in the search for reliable prognostic indicators for breast cancer.

6-oxo-PGF1 alpha -a new tumour marker for tumours in the maxillo-facial region

The diagnosis of secondary or recurrent tumour growth after operations on primary maxillo-facial tumours is still only possible at a late stage. On the other hand, the prostaglandins of the E series assume an important role in connection with tumour growth. The present investigation succeeded for the first time in detecting an increase in the level of 6-oxo-PGF1 alpha, the stable metabolite of PGI2, before planned radical operation in patients with maxillo-facial tumours. In the further course of the illness it was possible to establish a correlation between the plasma values and the occurrence of metastasis or recurrence of disease. These results indicate that a certain significance can be attributed to 6-oxo-PGF1 alpha as a tumour marker.

Prostaglandin concentrations and prostaglandin synthetase activity in N-nitrosomethylurea-induced rat mammary adenocarcinoma

A comparison of tissue concentrations and biosynthesis of prostaglandin (PG)E2, PGF2 alpha, 6-keto-PGF1 alpha (degradation production of PGI2) and thromboxane (TX)B2 (degradation product of TXA2) was made in normal mammary glands obtained from virgin female Sprague-Dawley rats and in N-nitrosomethylurea (NMU)-induced mammary adenocarcinomas. The tissue concentrations (ng/g wet weight) of all 4 compounds were significantly higher in the NMU-induced tumor than in normal mammary tissue: PGE2, 210 +/- 37 vs 25 +/- 6; PGF2 alpha, 287 +/- 48 vs 23 +/- 8; 6-keto-PGF1 alpha, 294 +/- 42 vs 31 +/- 8; and TXB2, 260 +/- 49 vs 27 +/- 5 (mean +/- S.E.M.). Microsomal prostaglandin synthetase activity in NMU-induced tumors was also significantly higher than in normal tissue for all but 6-keto-PGF1 alpha: PGE2, 226 +/- 16 vs 50 +/- 9; PGF2 alpha, 28 +/- 3 vs 4 +/- 1; 6-keto-PGF1 alpha, 14 +/- 2 vs 11 +/- 2; and TXB2, 17 +/- 1 vs 10 +/- 1 ng/mg protein (mean +/- S.E.M.). There was no apparent relationship between either tumor size or age and the ability of microsomal enzyme to synthesize prostaglandins, although the content of prostaglandins extracted from tumor tissue was inversely related to the tumor size.

Prostaglandins and gene action: possible relevance to the effect of PG system on leukocyte alkaline phosphatase enzyme activity

Prostaglandin E2, colchicine and imidazole, known to enhance and inhibit thromboxane A2 (TxA2) synthesis respectively and chloroquine, a PGE1 synthesis enhancer and PGE2 antagonist can alter the leukocyte alkaline phosphatase (LAP) enzyme activity. Thromboxane A2 and other related prostaglandins (PGs) are known to bind to DNA and thus possibly regulate DNA action. It is proposed here that prostaglandins are able to modify LAP activity by their action on the DNA and thus the Gene that codes for LAP. This hypothesis envisages that normally there are specific receptors on the genes for PGs. Taking LAP enzyme system as the model, it is proposed that the affinity of TxA1, TxA2, PGE2 and PGE1 to the operator is more than to that of the repressor. But when the levels of TxA2, PGE2 and PGE1 are in excess, all the receptors on the operator are not only completely occupied but they are also able to bind to repressor in sufficient amounts to transiently switch off the LAP synthesis by the structural gene. It is further envisaged that the affinity of the PG receptors on the operator and repressor systems of the operon is greatest for TxA1 and least for PGE2 (TxA1 greater than TxA2 greater than PGE1 greater than PGE2). This hypothesis though simply in its model explains all the variables obtained in our studies on the effect of PGs on the LAP activity. This concept by itself or a suitable modification, may explain the role of PGs in the pathogenesis of cancer. It will be interesting to study, in the light of this hypothesis, the role of the PG system on DNA repair mechanism, m-RNA and t-RNA synthesis and gene action in several systems.