Essential fatty acids enhance free radical generation and lipid peroxidation to induce apoptosis of tumor cells

Fumonisin B1 protects against long-chained polyunsaturated fatty acid-induced cell death in HepG2 cells - implications for cancer promotion

Fumonisin B1 (FB1), a food-borne mycotoxin, is a cancer promoter in rodent liver and augments proliferation of initiated cells while inhibiting the growth of normal hepatocytes by disrupting lipid biosynthesis at various levels. HepG2 cancer cells exhibited resistance to FB1-induced toxic effects presumably due to their low content of polyunsaturated fatty acids (PUFA) even though FB1-typical lipid changes were observed, e.g. significantly increased phosphatidylethanolamine (PE), decreased sphingomyelin and cholesterol content, increased sphinganine (Sa) and sphinganine/sphingosine ratio, increased C18:1ω-9, decreased C20:4ω-6 content in PE and decreased C20:4ω-6_PC/PE ratio. Increasing PUFA content of HepG2 cells with phosphatidylcholine (PC) vesicles containing C20:4ω-6 (SAPC) or C22:6ω-3 (SDPC) disrupted cell survival, cellular redox status and induced oxidative stress and apoptosis. A partially protective effect of FB1 was evident in PUFA-enriched HepG2 cells which may be related to the FB1-induced reduction in oxidative stress and the disruption of key cell membrane constituents indicative of a resistant lipid phenotype. Interactions between different ω-6 and ω-3 PUFA, membrane constituents including cholesterol, and the glycerophospho- and sphingolipids and FB1 in this cell model provide further support for the resistant lipid phenotype and its role in the complex cellular effects underlying the cancer promoting potential of the fumonisins.

Alpha-linolenic acid alleviates the detrimental effects of lipopolysaccharide during in vitro ovine oocyte development

During the transition period and early lactation of ruminants with higher production, the reproductive organs are exposed to various stressors, like inflammation stimulators such as lipopolysaccharides (LPS), as a consequence of high concentrate consumption. In this study, we aimed to determine the probable potential of α-linolenic acid (ALA) in alleviating LPS-induced effects in ovine oocytes in vitro as well as the underlying controlling mechanisms. Different concentrations of LPS (0, 0.01, 0.1, 1, and 10 μg/mL) were added to the oocyte maturation medium to evaluate its effect on oocyte developmental competence. Likewise, different concentrations of ALA (0, 10, 50, 100, and 200 μM/mL) were added to the maturation medium to define its effects on oocyte developmental competence. Accordingly, a combination of ALA and LPS in a dose-dependent manner was added to the maturation medium to elucidate their effect on oocyte developmental competence and uncover any possible potential of ALA to alleviate the detrimental effect induced by the presence of LPS. The expressions of candidate genes were measured in mature oocytes treated either with ALA, LPS, or ALA plus LPS. Adding LPS to the maturation medium decreased the cleavage rate of the treated oocytes, and those oocytes reached the blastocyst stage at a lower rate. Adding ALA to the maturation medium in the presence of LPS alleviated the detrimental effects of LPS in a dose-dependent manner, which ultimately led to higher cleavage and blastocyst formation. A higher expression of Trim26, GRHPR, NDUFA, PGC-1α, SOD, CS, SDH, p53, and CAT was observed in LPS-treated oocytes compared with the ALA and control groups. Additionally, CS and CAT transcripts were down-regulated in oocytes in LPS plus ALA-treated group compared to that of the LPS-treated group. These findings revealed that ALA has the potential to alleviate the detrimental effects induced by LPS on in ovine oocytes during maturation in vitro. Thus, LPS-detrimental effect and ALA-preventing mechanisms seem to be regulated through the expression of genes involved in mitochondrial biogenesis and function, oxidative stress, and antioxidant systems.

Infection, Inflammation, and Immunity in Sepsis

Sepsis is triggered by microbial infection, injury, or even major surgery. Both innate and adaptive immune systems are involved in its pathogenesis. Cytoplasmic presence of DNA or RNA of the invading organisms or damaged nuclear material (in the form of micronucleus in the cytoplasm) in the host cell need to be eliminated by various nucleases; failure to do so leads to the triggering of inflammation by the cellular cGAS-STING system, which induces the release of IL-6, TNF-α, and IFNs. These cytokines activate phospholipase A2 (PLA2), leading to the release of polyunsaturated fatty acids (PUFAs), gamma-linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which form precursors to various pro- and anti-inflammatory eicosanoids. On the other hand, corticosteroids inhibit PLA2 activity and, thus, suppress the release of GLA, AA, EPA, and DHA. PUFAs and their metabolites have a negative regulatory action on the cGAS-STING pathway and, thus, suppress the inflammatory process and initiate inflammation resolution. Pro-inflammatory cytokines and corticosteroids (corticosteroids > IL-6, TNF-α) suppress desaturases, which results in decreased formation of GLA, AA, and other PUFAs from the dietary essential fatty acids (EFAs). A deficiency of GLA, AA, EPA, and DHA results in decreased production of anti-inflammatory eicosanoids and failure to suppress the cGAS-STING system. This results in the continuation of the inflammatory process. Thus, altered concentrations of PUFAs and their metabolites, and failure to suppress the cGAS-STING system at an appropriate time, leads to the onset of sepsis. Similar abnormalities are also seen in radiation-induced inflammation. These results imply that timely administration of GLA, AA, EPA, and DHA, in combination with corticosteroids and anti-IL-6 and anti-TNF-α antibodies, may be of benefit in mitigating radiation-induced damage and sepsis.

Novel Formulation of Undecylenic Acid induces Tumor Cell Apoptosis

Undecylenic acid, a monounsaturated fatty acid, is currently in clinical use as a topical antifungal agent, however the potential for therapeutic application in other disease settings has not been investigated. In this study, we describe a novel platform for the solubilization of fatty acids using amino acids and utilize this approach to define a tumoricidal activity and underlying mechanism for undecylenic acid. We examined a novel formulation of undecylenic acid compounded with L-Arginine, called GS-1, that induced concentration-dependent tumor cell death, with undecylenic acid being the cytotoxic component. Further investigation revealed that GS-1-mediated cell death was caspase-dependent with a reduction in mitochondrial membrane potential, suggesting a pro-apoptotic mechanism of action. Additionally, GS-1 was found to localize intracellularly to lipid droplets. In contrast to previous studies where lipid droplets have been shown to be protective against fatty acid-induced cell death, we showed that lipid droplets could not protect against GS-1-induced cytotoxicity. We also found a role for Fatty Acid Transport Protein 2 (FATP2) in the uptake of this compound. Collectively, this study demonstrates that GS-1 has effective pro-apoptotic antitumor activity in vitro and, together with the novel platform of fatty acid solubilization, contributes to the re-emerging field of fatty acids as potential anti-cancer therapeutics.

Pro- and anti-inflammatory bioactive lipids imbalance contributes to the pathobiology of autoimmune diseases

Autoimmune diseases are driven by T_H17 cells that secrete pro-inflammatory cytokines, especially IL-17. Under normal physiological conditions, autoreactive T cells are suppressed by TGF-β and IL-10 secreted by microglia and dendritic cells. When this balance is upset due to injury, infection and other causes, leukocyte recruitment and macrophage activation occurs resulting in secretion of pro-inflammatory IL-6, TNF-α, IL-17 and PGE2, LTs (leukotrienes) accompanied by a deficiency of anti-inflammatory LXA4, resolvins, protecting, and maresins. PGE2 facilitates T_H1 cell differentiation and promotes immune-mediated inflammation through T_H17 expansion. There is evidence to suggest that autoimmune diseases can be suppressed by anti-inflammatory bioactive lipids LXA4, resolvins, protecting, and maresins. These results imply that systemic and/or local application of LXA4, resolvins, protecting, and maresins and administration of their precursors AA/EPA/DHA could form a potential therapeutic approach in the prevention and treatment of autoimmune diseases.

Gamma-Linolenic Acid (GLA) Protects against Ionizing Radiation-Induced Damage: An In Vitro and In Vivo Study

Radiation is pro-inflammatory in nature in view of its ability to induce the generation of reactive oxygen species (ROS), cytokines, chemokines, and growth factors with associated inflammatory cells. Cells are efficient in repairing radiation-induced DNA damage; however, exactly how this happens is not clear. In the present study, GLA reduced DNA damage (as evidenced by micronuclei formation) and enhanced metabolic viability, which led to an increase in the number of surviving RAW 264.7 cells in vitro by reducing ROS generation, and restoring the activities of desaturases, COX-1, COX-2, and 5-LOX enzymes, TNF-α/TGF-β, NF-kB/IkB, and Bcl-2/Bax ratios, and iNOS, AIM-2, and caspases 1 and 3, to near normal. These in vitro beneficial actions were confirmed by in vivo studies, which revealed that the survival of female C57BL/6J mice exposed to lethal radiation (survival~20%) is significantly enhanced (to ~80%) by GLA treatment by restoring altered levels of duodenal HMGB1, IL-6, TNF-α, and IL-10 concentrations, as well as the expression of NF-kB, IkB, Bcl-2, Bax, delta-6-desaturase, COX-2, and 5-LOX genes, and pro- and anti-oxidant enzymes (SOD, catalase, glutathione), to near normal. These in vitro and in vivo studies suggest that GLA protects cells/tissues from lethal doses of radiation by producing appropriate changes in inflammation and its resolution in a timely fashion.

Single nucleotide polymorphism of fatty acid desaturase gene and breast cancer risk in estrogen receptor subtype

BACKGROUND

Breast cancer (BC) is the most common cancer of women and the second most common cancer overall globally. Data suggest that the plasma concentration of omega fatty acids (n-3 and n-6) and the impact of the genetic variant are associated with diet-related inflammatory disease, BC. This study was aimed to find an association between genetic variant rs174537 of fatty acid desaturase gene 1(FADS 1) and breast cancer estrogen receptor subtype.

METHODOLOGY

Hundred and two blood samples from women were quantified for fatty acids by gas chromatography. SNP rs 174537(G > T) showed maximum variability and the strongest genetic determinant in the Genome-wide association study were genotyped using Sanger sequencing.

RESULTS

The highest tertile of ALA showed a significantly reduced risk of BC compared to the lowest tertile (OR = 0.2, 95 %CL = 0.1-1.14, P = 0.03). Median values of ALA were higher in GT/TT genotype in ER +ve molecular subtype (P = 0.03) and DPA was higher in GG genotype of ER-ve molecular subtype (P = 0.037). When both the groups were put together the highest tertile of GG tertile showed significantly reduced risk of BC compared with the other lowest tertiles of GG and GT/TT genotypes (OR, 95% CL = 0.45(0.2-0.9).

CONCLUSION

The high levels of arachidonic acid and low levels of n-3 fatty acids result in a pro-inflammatory milieu and that these pro-inflammatory effects might contribute to BC. We conclude that the individuals with genetically determined lower activity of FADS1(minor allele T) will derive greater advantage from n-3 FAs than those with higher FADS1 activity (G allele) and reduce the BC risk.

Arachidonic Acid as Mechanotransducer of Renin Cell Baroreceptor

For normal maintenance of blood pressure and blood volume a well-balanced renin-angiotensin-aldosterone system (RAS) is necessary. For this purpose, renin is secreted as the situation demands by the juxtaglomerular cells (also called as granular cells) that are in the walls of the afferent arterioles. Juxtaglomerular cells can sense minute changes in the blood pressure and blood volume and accordingly synthesize, store, and secrete appropriate amounts of renin. Thus, when the blood pressure and blood volume are decreased JGA cells synthesize and secrete higher amounts of renin and when the blood pressure and blood volume is increased the synthesis and secretion of renin is decreased such that homeostasis is restored. To decipher this important function, JGA cells (renin cells) need to sense and transmit the extracellular physical forces to their chromatin to control renin gene expression for appropriate renin synthesis. The changes in perfusion pressure are sensed by Integrin β1 that is transmitted to the renin cell’s nucleus via lamin A/C that produces changes in the architecture of the chromatin. This results in an alteration (either increase or decrease) in renin gene expression. Cell membrane is situated in an unique location since all stimuli need to be transmitted to the cell nucleus and messages from the DNA to the cell external environment can be conveyed only through it. This implies that cell membrane structure and integrity is essential for all cellular functions. Cell membrane is composed to proteins and lipids. The lipid components of the cell membrane regulate its (cell membrane) fluidity and the way the messages are transmitted between the cell and its environment. Of all the lipids present in the membrane, arachidonic acid (AA) forms an important constituent. In response to pressure and other stimuli, cellular and nuclear shape changes occur that render nucleus to act as an elastic mechanotransducer that produces not only changes in cell shape but also in its dynamic behavior. Cell shape changes in response to external pressure(s) result(s) in the activation of cPLA2 (cytosolic phospholipase 2)-AA pathway that stretches to recruit myosin II which produces actin-myosin cytoskeleton contractility. Released AA can undergo peroxidation and peroxidized AA binds to DNA to regulate the expression of several genes. Alterations in the perfusion pressure in the afferent arterioles produces parallel changes in the renin cell membrane leading to changes in renin release. AA and its metabolic products regulate not only the release of renin but also changes in the vanilloid type 1 (TRPV1) expression in renal sensory nerves. Thus, AA and its metabolites function as intermediate/mediator molecules in transducing changes in perfusion and mechanical pressures that involves nuclear mechanotransduction mechanism. This mechanotransducer function of AA has relevance to the synthesis and release of insulin, neurotransmitters, and other soluble mediators release by specialized and non-specialized cells. Thus, AA plays a critical role in diseases such as diabetes mellitus, hypertension, atherosclerosis, coronary heart disease, sepsis, lupus, rheumatoid arthritis, and cancer.

Advances on delta 5-unsaturated-polymethylene-interrupted fatty acids: Resources, biosynthesis, and benefits

Though the knowledge on delta 5-unsaturated-polymethylene-interrupted fatty acids (Δ5-UPIFAs) is being updated, the issue of their integration still exists within the field. Thus, this review systematically summarizes the sources, biosynthesis and metabolism, analytical methods, preparation, and health-promoting roles of Δ5-UPIFAs. In plants, the content of Δ5-UPIFAs is higher, which is an ideal source. In animals, although the content of Δ5-UPIFAs is not high, there are many species, which is the possible source of some special Δ5-UPIFAs. At present, although the extraction of Δ5-UPIFAs is mainly from plants, the fermentation by organisms, especially for genetically modified microorganisms engineering maybe be a substitue of pepration of Δ5-UPIFAs. Δ5-UPIFAs have been proved to possess multi-beneficial effects, such as lipid lowering, anti-inflammation and so on, so it has a certain potential application value. However, related knowledge of the underlying molecular mechanisms regarding Δ5-UPIFAs limited, and how Δ5-UPIFAs work is not clear. Further clinical and human studies about Δ5-UPIFAs are also needed. Studies on tapping new resources, developing structured lipide rich in Δ5-UPIFA and enhancing delivery were quite deficient. This review emphasizes the further directions on Δ5-UPIFAs with scientific suggestions to pay more attention to the applications of Δ5-UPIFAs in food, pharmaceutical and cosmetic industries.

γ-Linolenic Acid Prevents Lipid Metabolism Disorder in Palmitic Acid-Treated Alpha Mouse Liver-12 Cells by Balancing Autophagy and Apoptosis via the LKB1-AMPK-mTOR Pathway

Excessive fat deposition is the main character in nonalcoholic fatty liver disease (NAFLD), while γ-linolenic acid (GLA) is a polyunsaturated fatty acid that can reduce lipid deposition. This study investigated the effect and regulatory mechanism of GLA (100 μM) on lipid metabolism in alpha mouse liver 12 (AML-12) cells treated by 400 μM palmitic acid (PA). GLA reduced lipid content and increased fatty acid β oxidation, as indicated by decreasing triglyceride and cholesterol contents and increasing mRNA and protein expressions of CPT1α and PPARα. GLA relieved oxidative stress caused by PA, upregulated mRNA levels of superoxide dismutase and glutathione peroxidase, and decreased reactive oxygen species content. GLA reduced apoptosis, as indicated by decreases in the BAX/BCL2 expression level and apoptosis percentage. GLA activated autophagy, autophagosome-lysosome fusion, and LKB1-AMPK-mTOR signaling and upregulated mRNA and protein expressions of Beclin-1, autophagy-related 5, and liver kinase B1 (LKB1). These effects of GLA on lipid metabolism disorders of PA-treated hepatocytes were reversed by autophagy inhibitor 3MA and AMPK inhibitor compound C, confirming our conclusions. Overall, GLA can protect AML-12 cells from lipid metabolism disorder caused by PA via balancing autophagy and apoptosis mediated by the LKB1-AMPK-mTOR pathway. Consequently, GLA, as a dietary supplement, can help to prevent and treat NAFLD by regulating lipid metabolism and autophagy.

Stearoyl-CoA Desaturase 1 Potentiates Hypoxic plus Nutrient-Deprived Pancreatic Cancer Cell Ferroptosis Resistance

Hypoxia and nutrient starvation (H/NS) microenvironment, a notable characteristic of pancreatic carcinoma, plays a critical role in cell death resistance and tumor recurrence. However, its role in ferroptosis remains to be classified. Here, we found that H/NS contributed to the pancreatic cancer cell ferroptosis resistance depending on the altered intracellular lipid compositions. Mechanistically, H/NS induced the upregulation of stearoyl-CoA desaturase 1 (SCD1), which promoted monounsaturated fatty acids (MUFAs) synthesis and protected against lipid peroxidation. Surprisingly, SCD1 showed a strong correlation with antiferroptosis gene expression. Moreover, short-hairpin RNA-based knockdown of SCD1 enhanced erastin-induced ferroptosis in vitro under H/NS. Finally, our results demonstrate the synergistic effect of erastin and A939572, a special SCD1 inhibitor, in dictating pancreatic carcinoma subcutaneous ferroptotic death. Taken together, our findings reveal a new role of the H/NS microenvironment against ferroptosis and suggest a potential therapeutic strategy for overcoming ferroptosis resistance in pancreatic cancer cells.

"Cell Membrane Theory of Senescence" and the Role of Bioactive Lipids in Aging, and Aging Associated Diseases and Their Therapeutic Implications

Lipids are an essential constituent of the cell membrane of which polyunsaturated fatty acids (PUFAs) are the most important component. Activation of phospholipase A2 (PLA2) induces the release of PUFAs from the cell membrane that form precursors to both pro- and ant-inflammatory bioactive lipids that participate in several cellular processes. PUFAs GLA (gamma-linolenic acid), DGLA (dihomo-GLA), AA (arachidonic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are derived from dietary linoleic acid (LA) and alpha-linolenic acid (ALA) by the action of desaturases whose activity declines with age. Consequently, aged cells are deficient in GLA, DGLA, AA, AA, EPA and DHA and their metabolites. LA, ALA, AA, EPA and DHA can also be obtained direct from diet and their deficiency (fatty acids) may indicate malnutrition and deficiency of several minerals, trace elements and vitamins some of which are also much needed co-factors for the normal activity of desaturases. In many instances (patients) the plasma and tissue levels of GLA, DGLA, AA, EPA and DHA are low (as seen in patients with hypertension, type 2 diabetes mellitus) but they do not have deficiency of other nutrients. Hence, it is reasonable to consider that the deficiency of GLA, DGLA, AA, EPA and DHA noted in these conditions are due to the decreased activity of desaturases and elongases. PUFAs stimulate SIRT1 through protein kinase A-dependent activation of SIRT1-PGC1α complex and thus, increase rates of fatty acid oxidation and prevent lipid dysregulation associated with aging. SIRT1 activation prevents aging. Of all the SIRTs, SIRT6 is critical for intermediary metabolism and genomic stability. SIRT6-deficient mice show shortened lifespan, defects in DNA repair and have a high incidence of cancer due to oncogene activation. SIRT6 overexpression lowers LDL and triglyceride level, improves glucose tolerance, and increases lifespan of mice in addition to its anti-inflammatory effects at the transcriptional level. PUFAs and their anti-inflammatory metabolites influence the activity of SIRT6 and other SIRTs and thus, bring about their actions on metabolism, inflammation, and genome maintenance. GLA, DGLA, AA, EPA and DHA and prostaglandin E2 (PGE2), lipoxin A4 (LXA4) (pro- and anti-inflammatory metabolites of AA respectively) activate/suppress various SIRTs (SIRt1 SIRT2, SIRT3, SIRT4, SIRT5, SIRT6), PPAR-γ, PARP, p53, SREBP1, intracellular cAMP content, PKA activity and peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α). This implies that changes in the metabolism of bioactive lipids as a result of altered activities of desaturases, COX-2 and 5-, 12-, 15-LOX (cyclo-oxygenase and lipoxygenases respectively) may have a critical role in determining cell age and development of several aging associated diseases and genomic stability and gene and oncogene activation. Thus, methods designed to maintain homeostasis of bioactive lipids (GLA, DGLA, AA, EPA, DHA, PGE2, LXA4) may arrest aging process and associated metabolic abnormalities.

Tetrazanbigen Derivatives as Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Partial Agonists: Design, Synthesis, Structure-Activity Relationship, and Anticancer Activities

Tetrazanbigen (TNBG) is a novel sterol isoquinoline derivative with poor water solubility and moderate inhibitory effects on human cancer cell lines via lipoapoptosis induction. Herein, we developed a series of novel TNBG analogues with improved water solubility and antiproliferative activities. The CCK-8 assay enabled us to identify a novel compound, 14g, which strongly inhibited HepG2 and A549 cell growth with IC₅₀ values of 0.54 and 0.47 μM, respectively. The anticancer effects might be explained by the partial activation and upregulation of PPARγ expression, as indicated by the transactivation assay and western blotting evaluation. Furthermore, the in vitro antiproliferative activity was verified in an in vivo xenograft model in which 14g strongly reduced tumor growth at a dose of 10 mg/kg. In line with these positive observations, 14g exhibited an excellent water solubility of 31.4 mg/mL, which was more than 1000-fold higher than that of TNBG (4 μg/mL). Together, these results suggest that 14g is a promising anticancer therapeutic that deserves further investigation.

Mechanistic Insight into the Regulation of Lipoxygenase-Driven Lipid Peroxidation Events in Human Spermatozoa and Their Impact on Male Fertility

A prevalent cause of sperm dysfunction in male infertility patients is the overproduction of reactive oxygen species, an attendant increase in lipid peroxidation and the production of cytotoxic reactive carbonyl species such as 4-hydroxynonenal. Our previous studies have implicated arachidonate 15-lipoxygenase (ALOX15) in the production of 4-hydroxynonenal in developing germ cells. Here, we have aimed to develop a further mechanistic understanding of the lipoxygenase-lipid peroxidation pathway in human spermatozoa. Through pharmacological inhibition studies, we identified a protective role for phospholipase enzymes in the liberation of peroxidised polyunsaturated fatty acids from the human sperm membrane. Our results also revealed that arachidonic acid, linoleic acid and docosahexanoic acid are key polyunsaturated fatty acid substrates for ALOX15. Upon examination of ALOX15 in the spermatozoa of infertile patients compared to their normozoospermic counterparts, we observed significantly elevated levels of ALOX15 protein abundance in the infertile population and an increase in 4-hydroxynonenal adducts. Collectively, these data confirm the involvement of ALOX15 in the oxidative stress cascade of human spermatozoa and support the notion that increased ALOX15 abundance in sperm cells may accentuate membrane lipid peroxidation and cellular dysfunction, ultimately contributing to male infertility.

Human DECR1 is an androgen-repressed survival factor that regulates PUFA oxidation to protect prostate tumor cells from ferroptosis

Fatty acid β-oxidation (FAO) is the main bioenergetic pathway in human prostate cancer (PCa) and a promising novel therapeutic vulnerability. Here we demonstrate therapeutic efficacy of targeting FAO in clinical prostate tumors cultured ex vivo, and identify DECR1, encoding the rate-limiting enzyme for oxidation of polyunsaturated fatty acids (PUFAs), as robustly overexpressed in PCa tissues and associated with shorter relapse-free survival. DECR1 is a negatively-regulated androgen receptor (AR) target gene and, therefore, may promote PCa cell survival and resistance to AR targeting therapeutics. DECR1 knockdown selectively inhibited β-oxidation of PUFAs, inhibited proliferation and migration of PCa cells, including treatment resistant lines, and suppressed tumor cell proliferation and metastasis in mouse xenograft models. Mechanistically, targeting of DECR1 caused cellular accumulation of PUFAs, enhanced mitochondrial oxidative stress and lipid peroxidation, and induced ferroptosis. These findings implicate PUFA oxidation via DECR1 as an unexplored facet of FAO that promotes survival of PCa cells.

Antimicrobial, Antioxidant, and Anti-Tumor Activities of Sargassum linearifolium and Cystoseira crinita from Egyptian Mediterranean Coast

Brown algae earned importance by virtue of their promising secondary metabolites of reasonable biological activities. Herein, the antioxidant, antimicrobial, and anticancer effects of crude extracts obtained from two Egyptian brown seaweeds, Sargassum linearifolium and Cystoseira crinita were evaluated. Phytochemical and GC-MS analyses revealed numerous active secondary metabolites in C. crinita cold methanolic extract (CCME) and S. linearifolium hot aqueous extract (SHAE). Both SHAE and CCME exhibited comparable DPPH (124.5 vs 125.6 µg/ml) and ABTS (257.1 vs 254.8 µg/ml) scavenging activities, respectively. Moreover, both crude extracts exhibited antimicrobial activity against various pathogenic microorganisms. Interestingly, employing MTT assay revealed cytotoxic effects of both extracts against a panel of cancer cells, where CCME showed a strong cytotoxic activity against MCF-7 cells (IC50 = 18.0 ± 0.74 µg/ml), while SHAE exhibited a moderate effect (IC50 = 31.1 ± 1.04 µg/ml). Increased mRNA and protein expression of Bax and Beclin-1 as well as the decreased expression of Bcl-2 revealed the ability of both extracts to induce apoptosis and autophagy in MCF-7 cells. Collectively, these findings provide evidence for antioxidant, antimicrobial, as well as anticancer effects driven by the two brown seaweeds that may underlay their plausible application in the therapeutic uses.

The Effect of Diet Supplementation with Pomegranate and Bitter Melon on Lipidomic Profile of Serum and Cancerous Tissues of Rats with Mammary Tumours

The aim of this study was to present overall lipid profile of organisms with ongoing neoplastic process and applied diet supplementation with pomegranate seed oil (PSO) and bitter melon extract (BME). The following were quantified in serum and cancerous tissues of rats suffering from mammary tumours: fatty acids, conjugated fatty acids and sterols, their oxidised metabolites (malondialdehyde and oxysterols) and lipoxygenase (LOX) metabolites of polyunsaturated fatty acids. The obtained results indicate that abnormalities in lipid metabolism accompany neoplastic process. These differences concern all classes of lipids and most pathways of their transformation, with the special emphasis on lipid peroxidation and LOX-mediated metabolism. Cancer process appears to be so detrimental that it may conceal positive influence of dietary modifications. The lack of anticarcinogenic properties of PSO and BME in this model may be due to their antioxidant properties or elevated levels of conjugated linoleic acids (CLA), which change CLA isomer activity from anti- to pro-tumorigenic. As CLA are the product of conjugated linolenic acids (CLnA) endogenous metabolism, high CLA levels may be explained by applied diet enrichment.

Bioactive Lipids in Age-Related Disorders

Our own studies and those of others have shown that defects in essential fatty acid (EFA) metabolism occurs in age-related disorders such as obesity, type 2 diabetes mellitus, hypertension, atherosclerosis, coronary heart disease, immune dysfunction and cancer. It has been noted that in all these disorders there could occur a defect in the activities of desaturases, cyclo-oxygenase (COX), and lipoxygenase (LOX) enzymes leading to a decrease in the formation of their long-chain products gamma-linolenic acid (GLA), arachidonic acid, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). This leads to an increase in the production of pro-inflammatory prostaglandin E2 (PGE2), thromboxanes (TXs), and leukotrienes (LTs) and a decrease in anti-inflammatory lipoxin A4, resolvins, protectins and maresins. All these bioactive molecules are termed as bioactive lipids (BALs). This imbalance in the metabolites of EFAs leads to low-grade systemic inflammation and at times acute inflammatory events at specific local sites that trigger the development of various age-related disorders such as obesity, type 2 diabetes mellitus, hypertension, coronary heart disease, atherosclerosis, and immune dysfunction as seen in rheumatoid arthritis, lupus, nephritis and other localized inflammatory conditions. This evidence implies that methods designed to restore BALs to normal can prevent age-related disorders and enhance longevity and health.

Saturated Fatty Acids, MUFAs and PUFAs Regulate Ferroptosis

Apoptosis, necroptosis, autophagy, and ferroptosis are distinct mechanisms of cell death. In this issue of Cell Chemical Biology, Magtanong et al. (2019) demonstrated that exogenous monounsaturated fatty acids (MUFAs) induce a ferroptosis-resistant cell state by suppressing the accumulation of lipid peroxides and decreasing levels of oxidizable polyunsaturated fatty acids (PUFAs).

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

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

Effects of carbon nanotube on denitrification performance of Alcaligenes sp. TB: Promotion of electron generation, transportation and consumption

Multi-walled carbon nanotubes (MWCNTs) promote biodegradation in water treatment, but the effect of MWCNT on denitrification under aerobic conditions is still unclear. This investigation focused on the denitrification performance of MWCNT and its toxic effects on Alcaligenes sp. TB which showed that 30 mg/L MWCNTs increased NO₃^- removal efficiency from 84% to 100% and decreased the NO₂^-and N₂O accumulation rates by 36% and 17.5%, respectively. Nitrite reductase and nitrous oxide reductase activities were further increased by 19.5% and 7.5%, respectively. The mechanism demonstrated that electron generation (NADH yield) and electron transportation system activity increased by 14.5% and 104%, respectively. Cell membrane analysis found that MWCNT caused an increase in polyunsaturated fatty acids, which had positive effects on electron transportation and membrane fluidity at a low concentration of 96 mg/kg but caused membrane lipid peroxidation and impaired membrane integrity at a high concentration of 115 mg/L. These findings confirmed that MWCNT affects the activity of Alcaligenes sp. TB and consequently enhances denitrification performance.

Bioactive lipids as modulators of immune check point inhibitors

It is proposed that arachidonic acid (AA, 20:4 n-6) and other polyunsaturated fatty acids (PUFAs) in combination with immune check point inhibitors and tumor infiltrating lymphocytes (TILs) enhances the activity of T and NK cells and macrophages and thus, aids in the elimination of tumor cells and suppresses inflammatory side effects due to immune check point inhibitors.

Arachidonic acid activates extrinsic apoptotic pathway to enhance tumoricidal action of bleomycin against IMR-32 cells

Bleomycin is a commonly used anti-cancer drug in the management of a variety of cancers. Previously, we showed that arachidonic acid (AA) augmented the growth inhibitory action of bleomycin on IMR-32 (human neuroblastoma cells) in vitro by enhancing oxidative stress. Despite these results, the exact molecular mechanism of cytotoxic action of bleomycin and its augmentation by AA is not known. Our current study revealed that a combination of bleomycin and AA significantly enhanced the expression of FAS gene, which is involved in programmed cell death (apoptosis) and caspases 3 and 8 compared to either bleomycin or AA alone implying that activation of extrinsic apoptotic pathway plays a major role in their (bleomycin + AA) tumoricidal action. It is interesting to note that AA by itself enhanced the expression of FAS and caspases 3 and 8 compared to control. Since caspases have a role in inflammation, cell proliferation, tumour suppression, cell differentiation, neural development and axon guidance and ageing, this may explain pleiotropic actions of AA and their metabolites.

Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review

Arachidonic acid (AA 20:4n-6) is an essential component of cell membranes and modulates cell membrane fluidity. AA is metabolized by cyclo-oxygenase (COX), lipoxygenase (LOX) and cytochrome P450 enzymes to form several metabolites that have important biological actions. Of all the actions, role of AA in the regulation of blood pressure and its ability to prevent both type 1 and type 2 diabetes mellitus seems to be interesting. Studies showed that AA and its metabolites especially, lipoxin A4 (LXA4) and epoxyeicosatrienoic acids (EETs), potent anti-inflammatory metabolites, have a crucial role in the pathobiology of hypertension and diabetes mellitus. AA, LXA4 and EETs regulate smooth muscle function and proliferation, voltage gated ion channels, cell membrane fluidity, membrane receptors, G-coupled receptors, PPARs, free radical generation, nitric oxide formation, inflammation, and immune responses that, in turn, participate in the regulation blood pressure and pathogenesis of diabetes mellitus. In this review, role of AA and its metabolites LXA4 and EETs in the pathobiology of hypertension, pre-eclampsia and diabetes mellitus are discussed. Based on several lines of evidences, it is proposed that a combination of aspirin and AA could be of benefit in the prevention and management of hypertension, pre-eclampsia and diabetes mellitus.

Profiling of Heterobranchia Sea Slugs from Portuguese Coastal Waters as Producers of Anti-Cancer and Anti-Inflammatory Agents

Bioprospection of marine invertebrates has been predominantly biased by the biological richness of tropical regions, thus neglecting macro-organisms from temperate ecosystems. Species that were not the object of studies on their biochemical composition include the Heterobranchia gastropods Armina maculata, Armina tigrina and Aglaja tricolorata, inhabitants of the Portuguese Atlantic coastal waters. Here, we present for the first time the fatty acid profile of neutral lipids and homarine content of these three species. Qualitative and quantitative differences in the fatty acid content among species points to the existence of a fatty acid profile of neutral lipids, particularly of each genus. The results from cytotoxicity assays, using the acetonic extracts of the gastropods on human gastric adenocarcinoma (AGS) and human lung adenocarcinoma (A549) cell lines, revealed a pronounced cytotoxic effect of the A. tigrina extract on both cell lines (IC₅₀ values of 68.75 and 69.77 μg mL⁻¹ for AGS and A549, respectively). It is worth noting the significant reduction of NO levels in LPS-challenged RAW 264.7 macrophages exposed to A. tricolorata extract, at concentrations as low as 125 μg mL⁻¹.

Potential Application of Eicosapentaenoic Acid Monoacylglyceride in the Management of Colorectal Cancer

Background: There is increasing evidence that marine omega-3 oils are involved in the reduction of cancer risk and progression. However, the anticancer effect of omega-3 monoglyceride on colorectal cancer has yet to be assessed. The goal of this study was to evaluate the anti-cancer effects of eicosapentaenoic acid monoglyceride (MAG-EPA) in HCT116 colorectal carcinoma cells. Methods: The effect of MAG-EPA was evaluated in vitro on HCT116 cells and in vivo on mouse model of HCT116 xenograft. Results: Our data reveal that MAG-EPA decreased cell proliferation and induced apoptosis in HCT116 cells. In a xenograft mouse model, daily per os administration of MAG-EPA reduced tumor growth. Furthermore, MAG-EPA treatments decreased EGFR, VEGFR, and AKT activation pathways and reduced VEGF and HIF1α expression levels in tumors. Conclusion: MAG-EPA may promote apoptosis and inhibit growth of tumors by suppressing EGFR and VEGFR activation pathways. Altogether, these data provide new evidence regarding the mode of action of MAG-EPA in colorectal cancer cells.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

Comparative Correlation Between Chemical Composition and Cytotoxic Potential of the Coral-Associated Fungus Aspergillus sp. 2C1-EGY Against Human Colon Cancer Cells

Cancer is a leading cause of death in several countries. In the search for new anticancer drugs, marine organisms have played an important role in the discovery of lead compounds and the development of new pharmaceuticals for their wide diversity of chemical structures and biological activities. In the present study, the cytotoxicity on colorectal cancer cells HCT116 exerted by marine fungus Aspergillus sp. 2C1-EGY extracts associated with the soft coral Sinularia sp. was investigated; the sub-fractions Fr 2c and Fr 2d had significantly high cytotoxic activity (88 and 85%, respectively). Moreover, the major hexadecanoic, octadecanoic, and octadecenoic acids as well as their methyl esters were isolated. GC/MS analysis revealed the identification of 46 major and minor compounds, from which 19 saturated and unsaturated fatty acids and eight fatty acid esters were identified.

Effect of eicosapentaenoic acid on bovine cumulus-oocyte complex in vitro

The aim of the present study was to investigate the effects of eicosapentaenoic acid (EPA) supplementation during in vitro maturation (IVM) of bovine oocytes. The concentrations tested in all experiments were 1 nM, 1 μM, and 1 mM EPA. The effect of EPA was evaluated on cumulus-oocyte complexes (COC) by oocyte maturation (cumulus expansion area and oocyte nuclear maturation), genotoxicity [single cell gel electrophoresis (SCGE)], and cytotoxicity (apoptosis, viability, and MTT assays) end points. The maturation parameters were affected by exposure of COC to different EPA concentrations in the IVM medium. Cumulus expansion area increased in the presence of 1 nM EPA (P < 0.05) whereas addition of 1 nM EPA (P < 0.05) decreased cumulus expansion after 24 h of IVM. Moreover, the maturation rate significantly decreased when 1 mM of EPA was assayed (P < 0.001). EPA at 1 nM induced genotoxic and cytotoxic effects on bovine cumulus cells (CC) and primary DNA lesions (P < 0.001). A significant increase in the frequency of apoptotic (P < 0.01) and necrotic (P < 0.001) cells was observed after 24 h of treatment with 1 nM, 1 μM, and 1 mM EPA. Mitochondrial activity was altered with 1 mM EPA (P < 0.001). We inferred that optimal oocyte quality was partially dependent on the presence of adequate EPA concentrations; EPA could be beneficial to improve oocyte quality in the maturation process, because low concentration tested (1 nM EPA) improved cumulus expansion.

Differential modulation of the lipid metabolism as a model for cellular resistance to fumonisin B1-induced cytotoxic effects in vitro

Differential sensitivity of primary hepatocytes and Chang cells to the cancer promoter fumonisin B1 (FB1)-induced cytotoxic effects were investigated in relation to changes in membrane lipid distribution. In contrast to primary hepatocytes, Chang cells were resistant to FB1-induced cytotoxic effects. This was associated with a high cholesterol (Chol) and sphingomyelin (SM) and low phosphatidylcholine (PC) content, resulting in a significant (P<0.05) decrease in phosphatidylethanolamine (PE)/PC ratio, increased Chol/total phosphoglyceride (TPG) ratios and low total polyunsaturated fatty acids (PUFA) content in PC and PE, suggesting a more rigid membrane structure. High levels of C18:1 and reduced polyunsaturated fatty acid (PUFA) levels are likely to provide selective resistance to FB1-induced oxidative stress. FB1-associated lipid changes included decreases in SM and Chol, increases in sphinganine (Sa) and PE with the increases in key saturated, monounsaturated, and PUFAs in PE as key role players in the differential responses to FB1-induced cell growth responses in cells.

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

Background

Colorectal cancer is common. Polyunsaturated fatty acids (PUFAs) exert growth-inhibitory and pro-apoptotic effects on colon cancer cells. Metabolites of PUFAs such as prostaglandins (PGs), leukotrienes (LTs) and lipoxins (LXs) play a significant role in colon cancer.

Methods

Human colon cancer LoVo and RKO cells were cultured with different concentration of PUFAs and 5-fluorouracil (5-FU) in vitro. Cell morphological changes, fatty acid composition, formation of PGE2, LTB4 and LXA4 and expression of COX-2, ALOX5, PGD synthase (PGDS), microsomal prostaglandin E synthase (mPGES) were assessed in LoVo and RKO cells when supplemented with PUFAs and 5-FU.

Results

PUFAs and 5-FU inhibited growth of LoVo and RKO cells to the same extent at the doses used and produced significant alterations in their shape. As expected, higher concentrations of supplemented PUFAs were noted in the cells compared to control. LA, GLA, AA, ALA and EPA supplementation to LoVo cells suppressed production of PGE₂, LTB₄,and ALOX5, mPGES expression, but enhanced that of LXA₄; whereas DHA enhanced PGE₂ and LXA₄ synthesis but decreased LTB₄ formation and COX-2, ALOX5, mPGES expression. In contrast, 5-FU enhanced formation of PGE₂, LTB₄ and mPGES expression, but suppressed LXA₄ synthesis and COX-2 expression. PGE₂, LTB₄ synthesis and ALOX5 expression was suppressed by LA, GLA, ALA and DHA; whereas AA, EPA and 5-FU enhanced PGE₂ but paradoxically AA decreased and EPA and 5-FU enhanced LTB4 synthesis in RKO cells. All the PUFAs tested enhanced, while 5-FU decreased LXA₄ formation in RKO cells; whereas GLA, AA, and 5-FU augmented while LA, ALA, EPA and DHA enhanced COX-2 expression in RKO cells.

Conclusions

Tumoricidal action of PUFAs on colorectal LoVo and RKO cancer cells in vitro was associated with increased formation of LXA₄, decreased synthesis of PGE₂ and LTB₄ and suppressed expression of COX-2, ALOX5, mPGES, whereas 5-FU produced contrasting actions on these indices.

Effect of n-3 and n-6 unsaturated fatty acids on prostate cancer (PC-3) and prostate epithelial (RWPE-1) cells in vitro

Prostate cancer (PCa) is one of the leading causes of death in the elderly men. Polyunsaturated fatty acids (PUFAs) regulate proliferation of cancer cells. In the present study, we evaluated the effect of various PUFAs on the proliferation and survival of human prostate cancer (PC-3) and human prostate epithelial (RWPE-1) cells in vitro.

LA, GLA, AA, ALA, EPA and DHA (linoleic acid, gamma-linolenic acid, arachidonic acid, alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid respectively) when tested at 50, 100, 150, and 200 μM inhibited proliferation of RWPE-1 and PC-3 cells, except that lower concentrations of LA (25 μM) and GLA (5, 10 μM) promoted proliferation. Though all fatty acids tested produced changes in the production of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), lipoxin A₄ and free radical generation by RWPE-1 and PC-3 cells, there were significant differences in their ability to do so. As expected, supplementation of various n-3 and n-6 fatty acids to RWPE-1 and PC-3 cells enhanced the content of the added fatty acids and their long-chain metabolites in these cells. In contrast to previous results, we did not find any direct correlation between inhibition of cell proliferation induced by various fatty acids and free radical generation. These results suggest that polyunsaturated fatty acids suppress proliferation of normal and tumor cells by a variety of mechanisms that may partly depend on the type(s) of cell(s) being tested and the way these fatty acids are handled by the cells. Hence, it is suggested that more deeper and comprehensive studies are needed to understand the actions of fatty acids on the growth of normal and tumor cells.

Characterization and cytotoxicity studies of the rare 21:4 n-7 acid and other polyunsaturated fatty acids from the marine opisthobranch Scaphander lignarius, isolated using bioassay guided fractionation

The marine opisthobranch Scaphander lignarius has been analyzed in the systematic search for novel bioactive compounds in Arctic marine organisms using bioassay guided fractionation. A number of highly cytotoxic fractions were shown to contain mainly polyunsaturated fatty acids (PUFAs). Selected PUFAs were isolated and identified using both liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). It was shown that the opisthobranch contained unusual PUFAs such as several ω3 fatty acids and the ω7 heneicosa-5,8,11,14-tetraenoic acid (21:4 n-7) not isolated before. The organism was shown to be a very rich source of PUFAs and the activity of the isolated compounds against a range of human cancer cell lines (melanoma, colon carcinoma and breast carcinoma) is further reported. The ω7 PUFA was significantly more cytotoxic in comparison with reference ω6 arachidonic and ω3 eicosapentaenoic acid. A noteworthy non-selective cytotoxicity against normal lung fibroblasts was also established. The paper contains isolation protocols in addition to cytotoxicity data of the isolated compounds. The potential of marine mollusks as a source for rare PUFAs is also discussed.

New players for advanced prostate cancer and the rationalisation of insulin-sensitising medication

Obesity and type 2 diabetes are recognised risk factors for the development of some cancers and, increasingly, predict more aggressive disease, treatment failure, and cancer-specific mortality. Many factors may contribute to this clinical observation. Hyperinsulinaemia, dyslipidaemia, hypoxia, ER stress, and inflammation associated with expanded adipose tissue are thought to be among the main culprits driving malignant growth and cancer advancement. This observation has led to the proposal of the potential utility of "old players" for the treatment of type 2 diabetes and metabolic syndrome as new cancer adjuvant therapeutics. Androgen-regulated pathways drive proliferation, differentiation, and survival of benign and malignant prostate tissue. Androgen deprivation therapy (ADT) exploits this dependence to systemically treat advanced prostate cancer resulting in anticancer response and improvement of cancer symptoms. However, the initial therapeutic response from ADT eventually progresses to castrate resistant prostate cancer (CRPC) which is currently incurable. ADT rapidly induces hyperinsulinaemia which is associated with more rapid treatment failure. We discuss current observations of cancer in the context of obesity, diabetes, and insulin-lowering medication. We provide an update on current treatments for advanced prostate cancer and discuss whether metabolic dysfunction, developed during ADT, provides a unique therapeutic window for rapid translation of insulin-sensitising medication as combination therapy with antiandrogen targeting agents for the management of advanced prostate cancer.

Dietary docosahexaenoic Acid (22:6) incorporates into cardiolipin at the expense of linoleic Acid (18:2): analysis and potential implications

Cardiolipin is a signature phospholipid of major functional significance in mitochondria. In heart mitochondria the fatty acid composition of cardiolipin is commonly viewed as highly regulated due to its high levels of linoleic acid (18:2n − 6) and the dominant presence of a 4×18:2 molecular species. However, analysis of data from a comprehensive compilation of studies reporting changes in fatty acid composition of cardiolipin in heart and liver mitochondria in response to dietary fat shows that, in heart the accrual of 18:2 into cardiolipin conforms strongly to its dietary availability at up to 20% of total dietary fatty acid and thereafter is regulated. In liver, no dietary conformer trend is apparent for 18:2 with regulated lower levels across the dietary range for 18:2. When 18:2 and docosahexaenoic acid (22:6n − 3) are present in the same diet, 22:6 is incorporated into cardiolipin of heart and liver at the expense of 18:2 when 22:6 is up to ~20% and 10% of total dietary fatty acid respectively. Changes in fatty acid composition in response to dietary fat are also compared for the two other main mitochondrial phospholipids, phosphatidylcholine and phosphatidylethanolamine, and the potential consequences of replacement of 18:2 with 22:6 in cardiolipin are discussed.

The Interactions between Insulin and Androgens in Progression to Castrate-Resistant Prostate Cancer

An association between the metabolic syndrome and reduced testosterone levels has been identified, and a specific inverse relationship between insulin and testosterone levels suggests that an important metabolic crosstalk exists between these two hormonal axes; however, the mechanisms by which insulin and androgens may be reciprocally regulated are not well described. Androgen-dependant gene pathways regulate the growth and maintenance of both normal and malignant prostate tissue, and androgen-deprivation therapy (ADT) in patients exploits this dependence when used to treat recurrent and metastatic prostate cancer resulting in tumour regression. A major systemic side effect of ADT includes induction of key features of the metabolic syndrome and the consistent feature of hyperinsulinaemia. Recent studies have specifically identified a correlation between elevated insulin and high-grade PCa and more rapid progression to castrate resistant disease. This paper examines the relationship between insulin and androgens in the context of prostate cancer progression. Prostate cancer patients present a promising cohort for the exploration of insulin stabilising agents as adjunct treatments for hormone deprivation or enhancers of chemosensitivity for treatment of advanced prostate cancer.

Effect of polyunsaturated fatty acids on drug-sensitive and resistant tumor cells in vitro

Previous studies showed that γ-linolenic acid (GLA, 18: 3 ω-6), arachidonic acid (AA, 20:4 ω -6), eicosapentaenoic acid (EPA, 20: 5 ω -3) and docosahexaenoic acid (DHA, 22:6 ω -3) have selective tumoricidal action. In the present study, it was observed that dihomo-gamma-linolenic acid (DGLA) and AA, EPA and DHA have cytotoxic action on both vincristine-sensitive (KB-3-1) and resistant (KB-Ch^R-8-5) cancer cells in vitro that appeared to be a free-radical dependent process but not due to the formation of prostaglandins, leukotrienes and thromboxanes. Uptake of vincristine and fatty acids was higher while their efflux was lower in KB-3-1 cells compared with KB-Ch^R-8-5 cells, suggesting that drug resistant cells have an effective efflux pump. GLA, DGLA, AA, EPA and DHA enhanced the uptake and decreased efflux in both drug-sensitive and drug-resistant cells and augmented the susceptibility of tumor cells especially, of drug-resistant cells to the cytotoxic action of vincristine. These results suggest that certain polyunsaturated fatty acids have tumoricidal action and are capable of enhancing the cytotoxic action of anti-cancer drugs specifically, on drug-resistant cells by enhancing drug uptake and reducing its efflux. Thus, polyunsaturated fatty acids either by themselves or in combination with chemotherapeutic drugs have the potential as anti-cancer molecules.