Trans-10,cis-12, not cis-9,trans-11, conjugated linoleic acid inhibits G1-S progression in HT-29 human colon cancer cells

Unveiling the anticancer potentiality of single cell oils produced by marine oleaginous Paradendryphiella sp. under optimized economic growth conditions

Bioprospecting about new marine oleaginous fungi that produce advantageous bioproducts in a green sustainable process is the key of blue bioeconomy. Herein, the marine Paradendryphiella sp. was utilized for single cell oils (SCOs) production economically, via central composite design, the lipid content enhanced 2.2-fold by 5.5 g/L lipid yeild on seawater-based media supplemented with molasses concentration 50 g/L, yeast extract, 2.25 g/L at initial pH value (5.3) and 8 days of static incubation. Subsequently, the fatty acid methyl esters profiles of SCOs produced on optimized media under different abiotic conditions were determined; signifying qualitative and quantitative variations. Interestingly, the psychrophilic-prolonged incubation increased the unsaturation level of fatty acids to 59.34%, while ω-6 and ω-3 contents representing 23.53% and 0.67% respectively. Remarkably, it exhibited the highest EC100 dose by 677.03 µg/mL on normal human lung fibroblast Wi-38 cells. Meanwhile, it showed the highest inhibiting proliferation potential on cancer cell lines of A549, MDA-MB 231 and HepG-2 cells by 372.37, 417.48 and 365.00 µg/mL, respectively. Besides, it elevated the oxidative stress, the expression of key apoptotic genes and suppressed the expression of key oncogenes (NF-κB, BCL2 and cyclin D); implying its promising efficacy in cancer treatment as adjuvant drug. This study denoted the lipogenesis capacity of Paradendryphiella sp. under acidic/alkaline and psychrophilic/mesophilic conditions. Hereby attaining efficient and economic process under seasonal variation with different Egyptian marine sources to fill the gap of freshwater crisis and simultaneously preserve energy.

Conjugated Linoleic Acid strengthens the apoptotic effect of low-dose cisplatin in A549 cells by inducing Bcl-2 downregulation

One of the chemotherapeutic agents widely used in the treatment of non-small cell lung cancer (NSCLC) is cisplatin. However, the resistance of cancer cells to cisplatin and additionally serious side effects from cisplatin limit its use. Conjugated linoleic acid (CLA) has been shown to suppress the development of carcinogenesis in vitro and in vivo studies and has antitumoral activity in many cancers. The study aimed to investigate the potential effect of using cisplatin, the first-line treatment for NSCLC, in combination with CLA to increase its efficacy in low-dose use. MTT cytotoxicity assay was performed to determine the effects of CLA in combination with cisplatin on cell viability of NSCLC cell lines. The apoptotic effect of this combination on NSCLC cell lines and cell cycle distribution was determined by flow cytometry. At the same time, apoptosis and cell cycle-related gene expression levels were determined by Real-Time PCR. Combination treatment of low-dose cisplatin with CLA resulted in a significant decrease in cell viability compared to cisplatin alone, and an increase in the rate of apoptotic cells was observed. While cisplatin caused G1 phase arrest in cancer cells, there was an increase in cell percentages in S and G2 phases after combined application with CLA. In high-dose cisplatin administration, it was observed that the efficiency of the decrease in anti-apoptotic BCL2 expression related to resistance to chemotherapeutic agents was less than that of low-dose cisplatin administration. Combined administration of high-dose cisplatin with CLA significantly recovered BCL2 downregulation.

Bioactive compounds: Application of albumin nanocarriers as delivery systems

Enriched products with bioactive compounds (BCs) show the capacity to produce a wide range of possible health effects. Most BCs are essentially hydrophobic and sensitive to environmental factors; so, encapsulation becomes a strategy to solve these problems. Many globular proteins have the intrinsic ability to bind, protect, encapsulate, and introduce BCs into nutraceutical or pharmaceutical matrices. Among them, albumins as human serum albumin (HSA), bovine serum albumin (BSA), ovalbumin (OVA) and α-lactalbumin (ALA) are widely abundant, available, and applied in many industrial sectors, becoming promissory materials to encapsulate BCs. Therefore, this review focuses on researches about the main groups of natural origin BCs (namely phenolic compounds, lipids, vitamins, and carotenoids), the different types of nanostructures based on albumins to encapsulate them and the main fields of application for BCs-loaded albumin systems. In this context, phenolic compounds (catechins, quercetin, and chrysin) are the most extensively BCs studied and encapsulated in albumin-based nanocarriers. Other extensively studied subgroups are stilbenes and curcuminoids. Regarding lipids and vitamins; terpenes, carotenoids (β-carotene), and xanthophylls (astaxanthin) are the most considered. The main application areas of BCs are related to their antitumor, anti-inflammatory, and antioxidant properties. Finally, BSA is the most used albumin to produced BCs-loaded nanocarriers.

A review on engineered magnetic nanoparticles in Non-Small-Cell lung carcinoma targeted therapy

There are growing appeals forthe design of efficacious treatment options for non-small-cell lung carcinoma (NSCLC) as it accrues to ~ 85% cases of lung cancer. Although platinum-based doublet chemotherapy has been the main therapeutic intervention in NSCLC management, this leads to myriad of problems including intolerability to the doublet regimens and detrimental side effects due to high doses. A new approach is therefore needed and warrants the design of targeted drug delivery systems that can halt tumor proliferation and metastasis by targeting key molecules, while exhibiting minimal side effects and toxicity. This review aims to explore the rational design of magnetic nanoparticles for the development of tumor-targeting systems for NSCLC. In the review, we explore the anticancer merits of conjugated linoleic acid (CLA) and provide a concise incursion into its application for the invention of functionalized magnetic nanoparticles in the targeted treatment of NSCLC. Recent nanoparticle-based targeted chemotherapies for targeting angiogenesis biomarkers in NSCLC will also be reviewed to further highlight versatility of magnetic nanoparticles. These developments through molecular tuning at the nanoscale and supported by comprehensive pre-clinical studies could lead to the establishment of precise nanosystems for tumor-homing cancer therapy.

The Effects of Conjugated Linoleic Acids on Cancer

Conjugated linoleic acids (CLA) are distinctive polyunsaturated fatty acids. They are present in food produced by ruminant animals and they are accumulated in seeds of certain plants. These naturally occurring substances have demonstrated to have anti-carcinogenic activity. Their potential effect to inhibit cancer has been shown in vivo and in vitro studies. In this review, we present the multiple effects of CLA isomers on cancer development such as anti-tumor efficiency, anti-mutagenic and anti-oxidant activity. Although the majority of the studies in vivo and in vitro summarized in this review have demonstrated beneficial effects of CLA on the proliferation and apoptosis of tumor cells, further experimental work is needed to estimate the true value of CLA as a real anti-cancer agent.

Bacteroides, butyric acid and t10,c12-CLA changes in colorectal adenomatous polyp patients

BACKGROUND

Colorectal adenomatous polyps (CAPs) are considered precancerous lesions of colorectal cancer (CRC). The gut microbiota participates in the process of digestion and, in the process, produces metabolites, mainly short-chain fatty acids (SCFAs), secondary bile acids and conjugated linoleic acid (CLA). This study aimed to investigate the gut microbiota constituents and metabolites in the faeces of CAP patients to identify microbiota or metabolites that can be used as sensitive biological predictors and to provide a theoretical basis for the clinical treatment of CAPs.

METHODS

16S rRNA sequence analysis was used to detect microbial changes in the faeces of CAP patients. qPCR analysis was used to evaluate the ability of the microbiota to produce metabolites, and the contents of metabolites in faeces were detected by ion chromatography and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

Based on the detection of the gut microbiota, patients with CAPs had increased abundances of Bacteroides and Citrobacter, and the abundances of Weissella and Lactobacillus were decreased. We also explored gene expression, and the abundance of butyrate-producing bacterial genes was significantly increased in the faeces of CAP patients, but those of secondary bile acid-producing and CLA-producing bacterial genes showed no differences in faecal samples. The acetic acid and butyric acid contents were increased in the faeces of the CAP group, and the healthy control group had higher t10,c12-CLA contents.

CONCLUSION

The gut microbiota analysis results, assessed in faeces, showed that Bacteroides and Citrobacter were positively correlated with CAPs, which indicated that changes in specific genera might be detrimental to intestinal health. In addition, t10,c12-CLA played an important role in protecting the intestine.

Conjugated linoleic acid: A potent fatty acid linked to animal and human health

Conjugated linoleic acid (CLA) is a mixture of isomers of linoleic acid (C18:2 n-6), which is mostly found in the ruminant meat and dairy products. The CLA is known to have many potential health benefits, and considered a potent powerful fatty acid, which is linked to animal and human health. The present work aims to discuss the source and production, mechanism of action, and effects of CLA on humans, poultry, and ruminants by reviewing the recent studies carried out on CLA. Despite most of the recent studies indicating beneficial effects of CLA on improving body weight control parameters, its effects on reducing risk factors of cardiovascular diseases (CVD), inflammation, blood glucose, and insulin are still controversial, and need to be further studied in different hosts.

Trans10,cis12 conjugated linoleic acid inhibits proliferation and migration of ovarian cancer cells by inducing ER stress, autophagy, and modulation of Src

The goal of this study was to investigate the anti-cancer effects of Trans10,cis12 conjugated linoleic acid (t10,c12 CLA). MTT assays and QCM™ chemotaxis 96-wells were used to test the effect of t10,c12 CLA on the proliferation and migration and invasion of cancer cells. qPCR and Western Blotting were used to determine the expression of specific factors. RNA sequencing was conducted using the Illumina platform and apoptosis was measured using a flow cytometry assay. t10,c12 CLA (IC50, 7 μM) inhibited proliferation of ovarian cancer cell lines SKOV-3 and A2780. c9,t11 CLA did not attenuate the proliferation of these cells. Transcription of 165 genes was significantly repressed and 28 genes were elevated. Genes related to ER stress, ATF4, CHOP, and GADD34 were overexpressed whereas EDEM2 and Hsp90, genes required for proteasomal degradation of misfolded proteins, were downregulated upon treatment. While apoptosis was not detected, t10,c12 CLA treatment led to 9-fold increase in autophagolysosomes and higher levels of LC3-II. G1 cell cycle arrest in treated cells was correlated with phosphorylation of GSK3β and loss of β-catenin. microRNA miR184 and miR215 were upregulated. miR184 likely contributed to G1 arrest by downregulating E2F1. miR215 upregulation was correlated with increased expression of p27/Kip-1. t10,c12 CLA-mediated inhibition of invasion and migration correlated with decreased expression of PTP1b and decreased Src activation by inhibiting phosphorylation at Tyr416. Due to its ability to inhibit proliferation and migration, t10,c12 CLA should be considered for treatment of ovarian cancer.

The Gut Microbiota and their Metabolites: Potential Implications for the Host Epigenome

The gut microbiota represents a metabolically active biomass of up to 2 kg in adult humans. Microbiota-derived molecules significantly contribute to the host metabolism. Large amounts of bacterial metabolites are taken up by the host and are subsequently utilized by the human body. For instance, short chain fatty acids produced by the gut microbiota are a major energy source of humans.It is widely accepted that microbiota-derived metabolites are used as fuel for beta-oxidation (short chain fatty acids) and participate in many metabolic processes (vitamins, such as folic acid). Apart from these direct metabolic effects, it also becomes more and more evident that these metabolites can interact with the mammalian epigenetic machinery. By interacting with histones and DNA they may be able to manipulate the host's chromatin state and functionality and hence its physiology and health.In this chapter, we summarize the current knowledge on possible interactions of different bacterial metabolites with the mammalian epigenetic machinery, mostly based on in vitro data. We discuss the putative impact on chromatin marks, for example histone modifications and DNA methylation. Subsequently, we speculate about possible beneficial and adverse consequences for the epigenome, the physiology and health of the host, as well as plausible future applications of this knowledge for in vivo translation to support personal health.

Anti-cancer activities of ω-6 polyunsaturated fatty acids

The ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) are two major families of PUFAs present as essential cellular components which possess diverse bioactivities. The ω-3s, mainly found in seafood, are associated with many beneficial effects on human health, while the ω-6s are more abundant in our daily diet and could be implicated in many pathological processes including cancer development. Increasing evidence suggests that the adverse effects of ω-6s may be largely attributed to arachidonic acid (AA, a downstream ω-6) and the metabolite prostaglandin E2 (PGE2) that stems from its cyclooxygenase (COX)-catalyzed lipid peroxidation. On the other hand, two of AA's upstream ω-6s, γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA), are shown to possess certain anti-cancer activities, including inducing cell apoptosis and inhibiting cell proliferation. In this paper, we review the documented anti-cancer activities of ω-6 PUFAs, including the recent findings regarding the anti-cancer effects of free radical-mediated DGLA peroxidation. The possible mechanisms and applications of DGLA (and other ω-6s) in inducing anti-cancer activity are also discussed. Considering the wide availability of ω-6s in our daily diet, the study of the potential beneficial effect of ω-6 PUFAs may guide us to develop an ω-6-based diet care strategy for cancer prevention and treatment.

Ethanol extract of Innotus obliquus (Chaga mushroom) induces G1 cell cycle arrest in HT-29 human colon cancer cells

BACKGROUND/OBJECTIVES

Inonotus obliquus (I. obliquus, Chaga mushroom) has long been used as a folk medicine to treat cancer. In the present study, we examined whether or not ethanol extract of I. obliquus (EEIO) inhibits cell cycle progression in HT-29 human colon cancer cells, in addition to its mechanism of action.

MATERIALS/METHODS

To examine the effects of Inonotus obliquus on the cell cycle progression and the molecular mechanism in colon cancer cells, HT-29 human colon cancer cells were cultured in the presence of 2.5 - 10 µg/mL of EEIO, and analyzed the cell cycle arrest by flow cytometry and the cell cycle controlling protein expression by Western blotting.

RESULTS

Treatment cells with 2.5 - 10 µg/mL of EEIO reduced viable HT-29 cell numbers and DNA synthesis, increased the percentage of cells in G1 phase, decreased protein expression of CDK2, CDK4, and cyclin D1, increased expression of p21, p27, and p53, and inhibited phosphorylation of Rb and E2F1 expression. Among I. obliquus fractions, fraction 2 (fractionated by dichloromethane from EEIO) showed the same effect as EEIO treatment on cell proliferation and cell cycle-related protein levels.

CONCLUSIONS

These results demonstrate that fraction 2 is the major fraction that induces G1 arrest and inhibits cell proliferation, suggesting I. obliquus could be used as a natural anti-cancer ingredient in the food and/or pharmaceutical industry.

Phosphatidylcholine with cis-9,trans-11 and trans-10,cis-12 Conjugated Linoleic Acid Isomers: Synthesis and Cytotoxic Studies

Novel phosphatidylcholines and lysophosphatidylcholines with cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid (CLA) were synthesized in high yields (75–99 %). The in vitro cytotoxic activities of these compounds against three human cancer cell lines (HL-60, MCF-7, and HT-29) were evaluated. The results revealed that there are differences in the activity between phosphatidylcholine with cis-9,trans-11 and trans-10,cis-12 CLA acyl groups. 1,2-Di(9Z,11E)-octadecadienoyl-sn-glycero-3-phosphocholine was the most potent cytotoxic agent among all tested CLA derivatives and its IC50 (concentration of a compound that inhibits the proliferation of 50 % of the cancer cell population) was 29.4 µM against HL-60. Moreover, phosphatidylcholines with CLA acyls exhibited much lower cytotoxicity against non-cancer cells (Balb/3T3) than free CLA isomers.

Yeast cell surface display of linoleic acid isomerase from Propionibacterium acnes and its application for the production of trans-10, cis-12 conjugated linoleic acid

Conjugated linoleic acid (CLA), a family of geometric and positional isomers of linoleic acid, has many health-promoting properties. Different isomers of CLA may have very different physiological effects. In the current work, we explore the possibility to produce single isomer of CLA by using biocatalysis based on displayed biocatalysts on the yeast cell surfaces. A reporter system used to assess gene expression and protein distribution was established by combining the egfp gene to the N-terminus of Propionibacterium acnes pai gene encoding the linoleic isomerase onto vector pYD1. After induction of the yeast strains containing pYD1::egfp::pai with galactose, strong green fluorescence was observed on the surface of cells, demonstrating that the fusion protein was successfully displayed. Using the engineered strains as whole-cell biocatalyst, trans-10, cis-12 CLA was detected in the reaction mixture. To improve the biocatalytic potential of this system, the first 20 amino codons of pai were modified, and the catalytic reaction conditions were optimized. Optimization of the codon usage resulted in 35% increase of CLA production, and the maximum yield of CLA was observed within 20 H in the optimal conditions: pH 7.0, 4 mg/mL linoleic acid, 37 °C. The system established in the present work can guide the development of biocatalytic strategies to produce trans-10, cis-12 CLA single isomer.

Kaempferol Induces Cell Cycle Arrest in HT-29 Human Colon Cancer Cells

Background:

A greater intake of vegetables and fruits has been linked to a reduced incidence of colon cancer. Flavonoids are polyphenolic compounds which are broadly distributed in fruits and vegetables and display a remarkable spectrum of physiological activities, including anti-carcinogenic effects. The objective of this study was to determine the mechanisms by which kaempferol, a flavonol present in tea, apples, strawberries, and beans, inhibits the growth of HT-29 human colon cancer cells.

Methods:

To examine the effects of kaempferol on cell cycle progression in HT-29 cells, cells were treated with various concentrations (0–60 μmol/L) of kaempferol. Cell proliferation and DNA synthesis were evaluated by MTT assay and [³H]thymidine incorporation assay, respectively. Fluorescence-activated cell sorting analyses were conducted to calculate cell cycle phase distribution. Western blot analyses and in vitro kinase assays were used to estimate the expression of proteins involved in the regulation of cell cycle progression and the activity of cyclin-dependent kinase (CDK)s, respectively.

Results:

Kaempferol decreased viable cell numbers and [³H]thymidine incorporation into DNA of HT-29 cells in a dose-dependent manner. Kaempferol induced G1 cell cycle arrest within 6 h and G2/M arrest at 12 h. Kaempferol inhibited the activity of CDK2 and CDK4 as well as the protein expression of CDK2, CDK4, cyclins D1, cyclin E, and cyclin A, and suppressed the phosphorylation of retinoblastoma protein. Additionally, kaempferol decreased the levels of Cdc25C, Cdc2, and cyclin B1 proteins, as well as the activity of Cdc2.

Conclusions:

The present results indicate that kaempferol induces G1 and G2/M cell cycle arrest by inhibiting the activity of CDK2, CDK4, and Cdc2. The induction of cell cycle arrest may be one of the mechanisms by which kaempferol exerts anti-carcinogenic effects in colon cancer cells.

Effect of conjugated linoleic acid supplementation on inflammatory factors and matrix metalloproteinase enzymes in rectal cancer patients undergoing chemoradiotherapy

OBJECTIVES

The aims of this study were to determine the effect of conjugated linoleic acid (CLA) supplementation on inflammatory factors and matrix metalloproteinase (MMP) enzymes in rectal cancer patients undergoing chemoradiothetrapy.

METHOD AND MATERIAL

In this randomized, double-blind, placebo-controlled pilot study, 34 volunteer patients with rectal cancer undergoing chemoradiotherapy assigned into the CLA group (n = 16), receiving 3 g CLA/d, and placebo group (n = 18) receiving placebo capsules (sunflower oil) for 6 weeks. The supplementation began 1 week before starting RT (loading period) and continued every day during treatment. Before and after intervention, serum tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), IL-6, MMP-2, MMP-9, and high-sensitivity C-reactive protein (hsCRP) were measured by enzyme-linked immunosorbent assay (ELISA) kits and immunoturbidimetric method, respectively. Independent t tests and paired t tests were used to compare parameters between and within groups, respectively.

RESULTS

In the CLA group, the mean serum TNF-α, IL-1β, hsCRP, MMP-9, and MMP-2 levels reduced insignificantly. However, significant changes in TNF-α (P = 0.04), hsCRP (P = 0.03), and MMP-9 (P = 0.04) concentrations were observed in the CLA group when compared with the placebo group. The mean serum IL-6 level remained unchanged in the CLA group but increased remarkably in the placebo group.

CONCLUSION

According to our results, CLA supplementation improved inflammatory factors, MMP-2, and MMP-9 as biomarkers of angiogenesis and tumor invasion. It seems that CLA may provide new complementary treatment by reducing tumor invasion and resistance to cancer treatment in patients with rectal cancer.

Conjugated linoleic acid-induced apoptosis in mouse mammary tumor cells is mediated by both G protein coupled receptor-dependent activation of the AMP-activated protein kinase pathway and by oxidative stress

Conjugated linoleic acid (CLA) has shown chemopreventive activity in several tumorigenesis models, in part through induction of apoptosis. We previously demonstrated that the t10,c12 isomer of CLA induced apoptosis of TM4t mouse mammary tumor cells through both mitochondrial and endoplasmic reticulum (ER) stress pathways, and that the AMP-activated protein kinase (AMPK) played a critical role in the apoptotic effect. In the current study, we focused on the upstream pathways by which AMPK was activated, and additionally evaluated the contributing role of oxidative stress to apoptosis. CLA-induced activation of AMPK and/or induction of apoptosis were inhibited by infection of TM4t cells with an adenovirus expressing a peptide which blocks the interaction between the G protein coupled receptor (GPCR) and Gα(q), by the phospholipase C (PLC) inhibitor U73122, by the inositol trisphosphate (IP(3)) receptor inhibitor 2-APB, by the calcium/calmodulin-dependent protein kinase kinase α (CaMKK) inhibitor STO-609 and by the intracellular Ca(2+) chelator BAPTA-AM. This suggests that t10,c12-CLA may exert its apoptotic effect by stimulating GPCR through Gα(q) signaling, activation of phosphatidylinositol-PLC, followed by binding of the PLC-generated IP(3) to its receptor on the ER, triggering Ca(2+) release from the ER and finally stimulating the CaMKK-AMPK pathway. t10,c12-CLA also increased oxidative stress and lipid peroxidation, and antioxidants blocked its apoptotic effect, as well as the CLA-induced activation of p38 MAPK, a downstream effector of AMPK. Together these data elucidate two major pathways by which t10,c12-CLA induces apoptosis, and suggest a point of intersection of the two pathways both upstream and downstream of AMPK.

Effects of ruminant trans fatty acids on cardiovascular disease and cancer: a comprehensive review of epidemiological, clinical, and mechanistic studies

There are 2 predominant sources of dietary trans fatty acids (TFA) in the food supply, those formed during the industrial partial hydrogenation of vegetable oils (iTFA) and those formed by biohydrogenation in ruminants (rTFA), including vaccenic acid (VA) and the naturally occurring isomer of conjugated linoleic acid, cis-9, trans-11 CLA (c9,t11-CLA). The objective of this review is to evaluate the evidence base from epidemiological and clinical studies to determine whether intake of rTFA isomers, specifically VA and c9,t11-CLA, differentially affects risk of cardiovascular disease (CVD) and cancer compared with iTFA. In addition, animal and cell culture studies are reviewed to explore potential pro- and antiatherogenic mechanisms of VA and c9,t11-CLA. Some epidemiological studies suggest that a positive association with coronary heart disease risk exists between only iTFA isomers and not rTFA isomers. Small clinical studies have been conducted to establish cause-and-effect relationships between these different sources of TFA and biomarkers or risk factors of CVD with inconclusive results. The lack of detection of treatment effects reported in some studies may be due to insufficient statistical power. Many studies have used doses of rTFA that are not realistically attainable via diet; thus, further clinical studies are warranted. Associations between iTFA intake and cancer have been inconsistent, and associations between rTFA intake and cancer have not been well studied. Clinical studies have not been conducted investigating the cause-and-effect relationship between iTFA and rTFA intake and risk for cancers. Further research is needed to determine the health effects of VA and c9,t11-CLA in humans.

Catalytic production of conjugated fatty acids and oils

The reactive double bonds in conjugated vegetable oils are of high interest in industry. Traditionally, conjugated vegetable oils are added to paints, varnishes, and inks to improve their drying properties, while recently there is an increased interest in their use in the production of bioplastics. Besides the industrial applications, also food manufactures are interested in conjugated vegetable oils due to their various positive health effects. While the isomer type is less important for their industrial purposes, the beneficial health effects are mainly associated with the c9,t11, t10,c12 and t9,t11 CLA isomers. The production of CLA-enriched oils as additives in functional foods thus requires a high CLA isomer selectivity. Currently, CLAs are produced by conjugation of oils high in linoleic acid, for example soybean and safflower oil, using homogeneous bases. Although high CLA productivities and very high isomer selectivities are obtained, this process faces many ecological drawbacks. Moreover, CLA-enriched oils can not be produced directly with the homogeneous bases. Literature reports describe many catalytic processes to conjugate linoleic acid, linoleic acid methyl ester, and vegetable oils rich in linoleic acid: biocatalysts, for example enzymes and cells; metal catalysts, for example homogeneous metal complexes and heterogeneous catalysts; and photocatalysts. This Review discusses state-of-the-art catalytic processes in comparison with some new catalytic production routes. For each category of catalytic process, the CLA productivities and the CLA isomer selectivity are compared. Heterogeneous catalysis seems the most attractive approach for CLA production due to its easy recovery process, provided that the competing hydrogenation reaction is limited and the CLA production rate competes with the current homogeneous base catalysis. The most important criteria to obtain high CLA productivity and isomer selectivity are (1) absence of a hydrogen donor, (2) absence of catalyst acidity, (3) high metal dispersion, and (4) highly accessible pore architecture.

Effects of canola and corn oil mimetic on Jurkat cells

Background

The Western diet is high in omega-6 fatty acids and low in omega-3 fatty acids. Canola oil contains a healthier omega 3 to omega 6 ratio than corn oil. Jurkat T leukemia cells were treated with free fatty acids mixtures in ratios mimicking that found in commercially available canola oil (7% α-linolenic, 30% linoleic, 54% oleic) or corn oil (59% linoleic, 24% oleic) to determine the cell survival or cell death and changes in expression levels of inflammatory cytokines and receptors following oil treatment.

Methods

Fatty acid uptake was assessed by gas chromatography. Cell survival and cell death were evaluated by cell cycle analyses, propidium-iodide staining, trypan blue exclusion and phosphatidylserine externalization. mRNA levels of inflammatory cytokines and receptors were assessed by RT-PCR.

Results

There was a significant difference in the lipid profiles of the cells after treatment. Differential action of the oils on inflammatory molecules, following treatment at non-cytotoxic levels, indicated that canola oil mimetic was anti-inflammatory whereas corn oil mimetic was pro-inflammatory.

Significance

These results indicate that use of canola oil in the diet instead of corn oil might be beneficial for diseases promoted by inflammation.

Recombinant lactobacilli expressing linoleic acid isomerase can modulate the fatty acid composition of host adipose tissue in mice

We have previously demonstrated that oral administration of a metabolically active Bifidobacterium breve strain, with ability to form cis-9, trans-11 conjugated linoleic acid (CLA), resulted in modulation of the fatty acid composition of the host, including significantly elevated concentrations of c9, t11 CLA and omega-3 (n-3) fatty acids in liver and adipose tissue. In this study, we investigated whether a recombinant lactobacillus expressing linoleic acid isomerase (responsible for production of t10, c12 CLA) from Propionibacterium acnes (PAI) could influence the fatty acid composition of different tissues in a mouse model. Linoleic-acid-supplemented diets (2 %, w/w) were fed in combination with either a recombinant t10, c12 CLA-producing Lactobacillus paracasei NFBC 338 (Lb338), or an isogenic (vector-containing) control strain, to BALB/c mice for 8 weeks. A third group of mice received linoleic acid alone (2 %, w/w). Tissue fatty acid composition was assessed by GLC at the end of the trial. Ingestion of the strain expressing linoleic acid isomerase was associated with a 4-fold increase (P<0.001) in t10, c12 CLA in adipose tissues of the mice when compared with mice that received the isogenic non-CLA-producing strain. The livers of the mice that received the recombinant CLA-producing Lb338 also contained a 2.5-fold (albeit not significantly) higher concentration of t10, c12 CLA, compared to the control group. These data demonstrate that a single gene (encoding linoleic acid isomerase) expressed in an intestinal microbe can influence the fatty acid composition of host fat.

Effect of conjugated linoleic acid (CLA) on lipid profile and liver histology in laboratory rats fed high-fructose diet

The objective of the study was to assess the effect of CLA on serum lipid profile, plasma malondialdehyde and liver histology in Wistar rats fed high-fructose diet. Eighteen rats were randomly assigned to three experimental groups and fed for the next 21 days. The experimental diets were: I, Control; II, Fructose (63.2% of fructose); and III, CLA+Fructose (1% CLA and 63.2% of fructose). The experimental treatments had no effect on body weight of the rats. The LDL+VLDL cholesterol, TG and liver weight were significantly increased in animals fed Fructose. MDA concentrations were significantly increased in rats fed Fructose diet but CLA+Fructose diet had no effect on this marker. In the same line, the histological examination of the livers showed a series of morphological alterations, notably hepatic steatosis in animals fed high-fructose diet. No signs of the steatosis in rats fed CLA+Fructose diet were observed. In conclusion, CLA in high-fructose diet, decreases serum LDL+VLDL and TG and plasma MDA concentrations as well as liver weight and liver cholesterol, thus opposing the effects of high-fructose diet and showing a potential antiatherogenic effect. Similarly, dietary CLA fed at 1% level (w/w) in high-fructose diet, prevented steatosis observed histologically in livers of rats fed high-fructose diets.

An urgent need to include risk-benefit analysis in clinical trials investigating conjugated linoleic acid supplements in cancer patients

Malnutrition and weight loss are common in patients with cancer, both factors could potentially affect the response and tolerance to treatment, decreased quality of life, and thus associate them with poor survival. Conjugated linoleic acid (CLA) is shown to have beneficial health effects in healthy and disease situations including chemoprotective properties in various experimental cancer models. However, the anticarcinogenic property of CLA in animal and tissue culture models could not be confirmed in the Netherlands Cohort Study on Diet and Cancer and a prospective cohort of Swedish women. Cancer patients are already at increased risk of anorexia and there are evidences that CLA suppresses appetite even in healthy individuals. Risk/benefit analysis of CLA supplementation has never been reported before and it is not clear whether any beneficial anti-tumor effect of CLA prevails over its anti-appetite and/or weight lowering side effect in these patients. I suggest that clinical trials investigating CLA supplements in cancer patients, measure appropriate variables such as food intake, weight, and appetite change to yield preliminary data for future trials. I also suggest that data from previous trials that have administered CLA supplements to cancer patients be re-analyzed retrospectively to attempt to find out any effect from routine nutritional measures such as weight, serum albumin and such as those.

trans-10,cis-12 conjugated linoleic acid inhibits insulin-like growth factor-I receptor signaling in TSU-Pr1 human bladder cancer cells

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid; the major isomers are trans-10,cis-12 CLA (t10c12) and cis-9,trans-11 CLA (c9t11). CLA has been demonstrated to exert strong anticarcinogenic effects in a variety of experimental cancer models. We previously observed that CLA (a mixture of isomers) and t10c12 decreased the growth of TSU-Pr1 cells, whereas linoleic acid and c9t11 exerted no effects. In the current study, the mechanisms underlying the t10c12-mediated regulation of the growth of these bladder cancer cells were evaluated. TSU-Pr1 cells were incubated in serum-free medium with various concentrations of t10c12 or c9t11 in the presence or absence of insulin-like growth factor (IGF)-I. The incorporation of [(3)H]thymidine into DNA was decreased, and the number of annexin V-stained cells was increased after t10c12 treatment, whereas c9t11 had no effect on apoptosis or [(3)H]thymidine incorporation. Treatment with exogenous IGF-I alone increased the numbers of viable cells but did not counteract the t10c12-induced growth inhibition of TSU-Pr1 cells. t10c12 effected a dose-dependent reduction in IGF-I receptor (IGF-IR) transcripts and protein levels, whereas c9t11 exerted no effects. Additionally, t10c12 inhibited the IGF-I-induced phosphorylation of IGF-IR, the recruitment of the p85 regulatory subunit of phosphoinositide 3-kinase to IGF-IR, and the phosphorylation of Akt and extracellular signal-regulated kinase (ERK)-1/2. These results indicate that the inhibition of IGF-IR signaling and the activation of Akt and ERK-1/2 contributed to decreased cell proliferation and increased apoptosis in TSU-Pr1 cells treated with t10c12.

Conjugated linoleic acid suppresses colon carcinogenesis in azoxymethane-pretreated rats with long-term feeding of diet containing beef tallow

BACKGROUND

We have indicated previously that long-term feeding of beef tallow increases colorectal cancer in rats. In this study, we investigated the effects of conjugated linoleic acid (CLA) on colon carcinogenesis in rats under long-term feeding of beef tallow diets, pretreated with azoxymethane (AOM).

METHODS

Six-week-old male Sprague-Dawley rats were fed with 10% beef tallow diet only, 10% beef tallow with 1% CLA in triglyceride form (CLA-TG), or 10% beef tallow with 1% CLA in free fatty acid form (CLA-FFA). Colon carcinogenesis was induced by two intraperitoneal injections of AOM. Aberrant crypt foci (ACFs) were examined at 12 weeks. Cancer, cell proliferation, apoptosis, Wnt signaling, and the arachidonic acid cascade were examined at 44 weeks.

RESULTS

At 12 weeks, CLA-TG and CLA-FFA attenuated the increase in ACFs induced by 10% beef tallow and AOM pretreatment. At 44 weeks, both forms of CLA attenuated multiple colon cancers, and CLA-FFA reduced the incidence of colon cancer to 50% of that seen with CLA-TG. CLA-TG and CLA-FFA decreased the number of 5-bromo-2'-deoxyuridine-positive cells in AOM-pretreated rats fed with 10% beef tallow. CLA-FFA increased the number of apoptotic cells and the activity of caspase-3 in the colon mucosa, and CLA-TG enhanced the activity of caspase-3. Both forms of CLA suppressed Wnt signaling and the arachidonic acid cascade in rats treated with beef tallow and AOM.

CONCLUSION

These results suggested that CLA-TG and CLA-FFA suppressed colon carcinogenesis in rats with long-term feeding of a 10% beef tallow diet, through several mechanisms. The results of the present study with rats might be applicable to humans.

Metabolism and actions of conjugated linoleic acids on atherosclerosis-related events in vascular endothelial cells and smooth muscle cells

Conjugated linoleic acids (CLAs) are biologically highly active lipid compounds that have attracted great scientific interest due to their ability to cause either inhibition of atherosclerotic plaque development or even regression of pre-established atherosclerotic plaques in mice, hamsters and rabbits. The underlying mechanisms of action, however, are only poorly understood. Since cell culture experiments are appropriate to gain insight into the mechanisms of action of a compound, the present review summarizes data from cell culture studies about the metabolism and the actions of CLAs on atherosclerosis-related events in endothelial cells (ECs) and smooth muscle cells (SMCs), which are important cells contributing to atherosclerotic lesion development. Based on these studies, it can be concluded that CLAs exert several beneficial actions including inhibition of inflammatory and vasoactive mediator release from ECs and SMCs, which may help explain the anti-atherogenic effect of CLAs observed in vivo. The observation that significant levels of CLA metabolites, which have been reported to have significant biological activities, are well detectable in ECs and SMCs indicates that the anti-atherogenic effects observed with CLAs are presumably mediated not only by CLAs themselves but also by their metabolites.

trans-10,cis-12 Conjugated linoleic acid induces depolarization of mitochondrial membranes in HT-29 human colon cancer cells: a possible mechanism for induction of apoptosis

Conjugated linoleic acid (CLA), which is naturally present in a variety of foods such as milk fat and the meat of ruminant animals, has been demonstrated to exert chemoprotective effects in several tissues in experimental animals. CLA is a collective term, which denotes one or more positional and geometric isomers of octadecadienoic acid, with cis-9,trans-11 (c9t11) and trans-10,cis-12 CLA (t10c12) being the principal isomers in commercial preparations. We observed previously that physiological levels of CLA inhibited HT-29 cell growth, and the growth inhibitory effects of CLA were attributed to the effect of t10c12, but not c9t11. In the present study, we assessed the mechanisms by which physiological levels of CLA and t10c12 induce apoptosis in HT-29 cells. HT-29 cells were cultured for 3 days in serum-free medium in the presence of various concentrations of CLA (0-20 micromol/L) or t10c12 (0-4 micromol/L). Addition of CLA or t10c12 to culture medium resulted in a dose-dependent increase in the numbers of apoptotic cells. The results of western blot analysis of total cell lysates showed that CLA and t10c12 increased the levels of cleaved caspase-9, caspase-3, and poly(ADP-ribose) polymerase but did not alter the levels of Bcl-2 family member proteins. However, these fatty acids were shown to increase the translocation of Bad and Bax to the mitochondria, increase mitochondrial membrane permeability, and induce the release of cytochrome c and Smac/Diablo from the mitochondria. In addition, CLA and t10c12 diminished Akt content and Akt phosphorylation. These findings indicate that physiological levels of t10c12 induce apoptosis in HT-29 colon cancer cells, which is mediated via mitochondrion-mediated events associated with a decline in Akt activity, an increase in the translocation of the pro-apototic Bad and Bax to the mitochondria, and the subsequent disruption of normal mitochondrial membrane potential.

Effects of conjugated linoleic acid on myogenic and inflammatory responses in a human primary muscle and tumor coculture model

The antiproliferative and anti-inflammatory properties of conjugated linoleic acid (CLA) make it a potentially novel treatment in chronic inflammatory muscle wasting disease, particularly cancer cachexia. Human primary muscle cells were grown in coculture with MIA PaCa-2 pancreatic tumor cells and exposed to varying concentrations of c9,t11 and t10,c12 CLA. Expression of myogenic (Myf5, MyoD, myogenin, and myostatin) and inflammatory genes (CCL-2, COX-2, IL-8, and TNF-alpha) were measured by real-time PCR. The t10,c12 CLA isomer, but not the c9,t11 isomer, significantly decreased MIA PaCa-2 proliferation by between 15% and 19%. There was a marked decrease in muscle MyoD and myogenin expression (78% and 62%, respectively), but no change in either Myf5 or myostatin, in myotubes grown in coculture with MIA PaCa-2 cells. CLA had limited influence on these responses. A similar pattern of myogenic gene expression changes was observed in myotubes treated with TNF-alpha alone. Several-fold significant increases in CCL-2, COX-2, IL-8, and TNF-alpha expression in myotubes were observed with MIA PaCa-2 coculture. The c9,t11 CLA isomer significantly decreased basal expression of TNF-alpha in myotubes and could ameliorate its tumor-induced rise. The study provides insight into the anti-inflammatory and antiproliferative actions of CLA and its application as a therapeutic agent in inflammatory disease states.

Influence of conjugated linoleic acids on functional properties of vascular cells

Conjugated linoleic acids (CLA) are biologically highly active lipid compounds that inhibit the development of atherosclerotic plaques in experimental animals. The underlying mechanisms of action, however, are only poorly understood. Since cell-culture experiments are appropriate to provide a detailed view into the mechanisms of action of a compound, the present review summarises results fromin vitrostudies dealing with the effects of CLA isomers and CLA mixtures on functional properties of cells of the vascular wall, such as endothelial cells, smooth muscle cells and monocyte-derived macrophages, which are amongst the major cells contributing to atherosclerotic lesion development. Based on these studies, it can be concluded that CLA exert several beneficial actions in cells of the vascular wall through the activation of nuclear PPAR. These actions of CLA, which may, at least partially, explain the inhibition of atherogenesis by dietary CLA, include modulation of vasoactive mediator release from endothelial cells, inhibition of inflammatory and fibrotic processes in activated smooth muscle cells, abrogation of inflammatory responses in activated macrophages, and reduction of cholesterol accumulation in macrophage-derived foam cells.

Isomer-specific effects of conjugated linoleic acid on gene expression in RAW 264.7

Conjugated linoleic acid (CLA) is a mixture of dietary fatty acids that has various beneficial effects including decreasing cancer, atherosclerosis, diabetes and inflammation in animal models. Some controversy exists on the specific isomers of CLA that are responsible for the benefits observed. This study was conducted to examine how different CLA isomers regulate gene expression in RAW 264.7. A mouse macrophage cell line, RAW 264.7, was treated with five different CLA isomers (9E,11E-, 9Z,11E-, 9Z,11Z-, 10E,12Z- and 11Z,13E-CLA). Gene expression microarrays were performed, and several significantly regulated genes of interest were verified by a real-time polymerase chain reaction (PCR). Examination of the biological functions of various significantly regulated genes by the five CLA isomers showed distinct properties. Isomers 9E,11E-, 9Z,11Z-, 10E,12Z- and 11Z,13E-CLA decreased production of proinflammatory cytokines such as interleukin (IL)-1alpha, IL-1beta and IL-6. Many of CLA's effects are believed to be mediated by the fatty acid receptors such as the peroxisome proliferator-activated receptors (PPAR) and retinoid-X-receptors (RXR). Using PPAR and RXR specific antagonists and coactivator recruitment assays, it was evident that multiple mechanisms were responsible for gene regulation by CLA isomers. Coactivator recruitment by CLA isomers showed their distinct properties as selective receptor modulators for PPARgamma and RXRalpha. These studies demonstrate distinct isomer differences in gene expression by CLA and will have important ramifications for determining the potential therapeutic benefit of these dietary fatty acids in prevention of inflammation-related diseases.

Os efeitos do ácido linoléico conjugado no metabolismo animal: avanço das pesquisas e perspectivas para o futuro

Realizou-se uma revisão sistemática, sem restrição de data, sobre os efeitos fisiológicos do ácido linoléico conjugado sobre a regressão da carcinogênese, o estresse oxidativo, o metabolismo de lípides e glicose e a alteração da composição corporal. Objetivando estabelecer o aspecto histórico do avanço da pesquisa em ácido linoléico conjugado, consideraram-se artigos originais resultantes de trabalhos realizados com animais, com cultura de células e com humanos. Quanto às pesquisas sobre o efeito anticarcinogênico do ácido linoléico conjugado foram encontradas inúmeras evidências a esse respeito, especialmente na regressão dos tumores mamários e de cólon, induzida por ambos os isômeros os quais agem de maneiras distintas. Os pesquisadores se empenham em reinvestigar as propriedades antioxidantes do ácido linoléico conjugado. Embora tenham sido investigadas as propriedades antioxidantes, tem-se identificado efeito pró-oxidante, levando ao estresse oxidativo em humanos. Foram poucos os estudos que demonstraram efeito positivo significativo do ácido linoléico conjugado sobre o metabolismo dos lípides e da glicose e sobre a redução da gordura corporal, especialmente em humanos. Estudos sobre efeitos adversos foram também identificados. Há fortes indícios de que a ação deste ácido graxo conjugado sobre uma classe de fatores de transcrição - os receptores ativados por proliferadores de peroxissomo - e sobre a conseqüente modulação da expressão gênica, possa ser a explicação fundamental dos efeitos fisiológicos. Embora incipientes, os mais recentes estudos reforçam o conceito da nutrigenômica, ou seja, a modulação da expressão gênica induzida por compostos presentes na alimentação humana. O cenário atual estimula a comunidade científica a buscar um consenso sobre os efeitos do ácido linoléico conjugado em humanos, já que este está presente naturalmente em alguns alimentos, que, quando consumidos em quantidades adequadas e de forma freqüente, poderiam atuar como coadjuvantes na prevenção e no controle de inúmeras doenças crônicas.

Conjugated linoleic acid isomers and cancer

We reviewed the literature regarding the effects of conjugated linoleic acid (CLA) preparations enriched in specific isomers, cis9, trans11-CLA (c9, t11-CLA) or trans10, cis12-CLA (t10, c12-CLA), on tumorigenesis in vivo and growth of tumor cell lines in vitro. We also examined the potential mechanisms by which CLA isomers may alter the incidence of cancer. We found no published reports that examined the effects of purified CLA isomers on human cancer in vivo. Incidence of rat mammary tumors induced by methylnitrosourea was decreased by c9, t11-CLA in all studies and by t10, c12-CLA in just a few that included it. Those 2 isomers decreased the incidence of forestomach tumors induced by benzo (a) pyrene in mice. Both isomers reduced breast and forestomach tumorigenesis. The c9, t11-CLA isomer did not affect the development of spontaneous tumors of the intestine or mammary gland, whereas t10, c12-CLA increased development of genetically induced mammary and intestinal tumors. In vitro, t10, c12-CLA inhibited the growth of mammary, colon, colorectal, gastric, prostate, and hepatoma cell lines. These 2 CLA isomers may regulate tumor growth through different mechanisms, because they have markedly different effects on lipid metabolism and regulation of oncogenes. In addition, c9, t11-CLA inhibited the cyclooxygenase-2 pathway and t10, c12-CLA inhibited the lipooxygenase pathway. The t10, c12-CLA isomer induced the expression of apoptotic genes, whereas c9, t11-CLA did not increase apoptosis in most of the studies that assessed it. Several minor isomers including t9, t11-CLA; c11, t13-CLA; c9, c11-CLA; and t7, c11-CLA were more effective than c9, t11-CLA or t10, c12-CLA in inhibiting cell growth in vitro. Additional studies with purified isomers are needed to establish the health benefit and risk ratios of each isomer in humans.

Heterologous expression of linoleic acid isomerase from Propionibacterium acnes and anti-proliferative activity of recombinant trans-10, cis-12 conjugated linoleic acid

The linoleic acid isomerase enzyme from Propionibacterium acnes responsible for bioconversion of linoleic acid to trans-10, cis-12 conjugated linoleic acid (t10, c12 CLA) was cloned and overexpressed in Lactococcus lactis and Escherichia coli, resulting in between 30 and 50 % conversion rates of the substrate linoleic acid to t10, c12 CLA. The anti-proliferative activities of the fatty acids produced following isomerization of linoleic acid by L. lactis and E. coli were assessed using the human SW480 colon cancer cell line. Fatty acids generated from both L. lactis and E. coli contained a mixture of linoleic acid and t10, c12 CLA at a ratio of ∼1.35 : 1. Following 5 days of incubation of SW480 cells with 5–20 μg ml⁻¹ (17.8–71.3 μM) of the t10, c12 CLA, there was a significant (P<0.001) reduction in growth of the SW480 cancer cells compared with the linoleic acid control. Cell viability after treatment with the highest concentration (20 μg ml⁻¹) of the t10, c12 CLA was reduced to 7.9 % (L. lactis CLA) and 19.6 % (E. coli CLA), compared with 95.4 % (control linoleic acid) and 31.7 % (pure t10, c12 CLA). In conclusion, this is believed to represent the first report in which recombinant strains are capable of producing CLA with an anti-proliferative potential.

Conjugated linoleic acid alters global gene expression in human intestinal-like Caco-2 cells in an isomer-specific manner

Conjugated linoleic acid (CLA) exhibits isomer-specific effects on transepithelial calcium (Ca) transport as well as on cell growth in human intestinal-like Caco-2 cells. However, the molecular mechanisms of action are still unclear. Therefore, this study used a transcriptomic approach to help elucidate the molecular mechanisms underlying such isomer-specific effects. Caco-2 cells were treated with 80 micromol/L linoleic acid (control), 80 micromol/L trans-10, cis-12 CLA, or 80 micromol/L cis-9, trans-11 CLA for 12 d. Ca transport was measured radio-isotopically. RNA was isolated from the cells, labeled, and hybridized to the Affymetrix U133 2.0 Plus arrays (n = 3). Data and functional analysis was preformed using Bioconductor. Using a minimum fold-change criterion of 1.6 and a false discovery rate criterion of P-value <or= 0.05, trans-10, cis-12 CLA altered the expression of 918 genes, whereas, cis-9, trans-11 CLA had no effect on gene expression. Gene ontology analysis revealed that trans-10, cis-12 CLA strongly modulated a number of processes inherently related to carcinogenesis, such as cell cycle, cell proliferation, and DNA metabolism. Trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, increased transepithelial Ca transport in Caco-2 cells, which corresponded to changes in molecular mediators of paracellular (including claudin 2 and 4) and transcellular (calbindin D(9)k and vitamin D receptor) Ca transport. This microarray-based study highlighted a number of gene expression patterns of relevance to 2 important intestinal processes (carcinogenesis and Ca transport), which were modulated by trans-10, cis-12 CLA. These may help our mechanistic understanding of the role of CLA in promoting gut function and health.

Functional effects of eggs, naturally enriched with conjugated linoleic acid, on the blood lipid profile, development of atherosclerosis and composition of atherosclerotic plaque in apolipoprotein E and low-density lipoprotein receptor double-knockout mice (apoE/LDLR− / − )

The objective of this study was to evaluate potential anti-atherogenic properties of hen eggs enriched naturally with conjugated linoleic acid (CLA) isomers (cis-9,trans-11 andtrans-10,cis-12). Eighteen apoE and LDL receptor double-knockout mice (apoE/LDLR− / − ), at the age of 4 months with pre-established atherosclerosis, were randomly assigned to three experimental groups (n6) and fed AIN-93G-based diets for the next 2 months. The experimental diets were: AIN-93G+ CLA-free egg-yolk powder (control); AIN-93G+ CLA-free egg-yolk powder +0·1 % CLA (CLA-supplemented eggs); and AIN-93G+ CLA-enriched egg-yolk powder, providing 0·1 % CLA (CLA-enriched eggs). For assessment of anti-atherogenic properties of CLA-enriched or CLA-supplemented eggs the following criteria were used: (1) serum lipid profile; (2) development of atherosclerosis; and (3) composition of atherosclerotic plaque. CLA-enriched eggs, compared with CLA-supplemented eggs, reduced significantly (P < 0·05) total plasma cholesterol in the mice. At the same time, both CLA-supplemented eggs and CLA-enriched eggs tended to decrease the size of atherosclerotic plaque in aortic roots of mice. Most importantly, atherosclerotic plaques of mice fed CLA-enriched eggs showed significantly (P < 0·05) reduced number of atherogenic macrophages and increased area occupied by smooth muscle cells in atherosclerotic lesions. In conclusion, CLA-enriched eggs exerted an anti-inflammatory effect more effectively than CLA-supplemented eggs. This anti-inflammatory effect can be considered their major functional claim that warrants further exploitation.

Antiproliferative effect of conjugated linoleic acid in caco-2 cells: involvement of PPARgamma and APC/beta-catenin pathways

Conjugated linoleic acid (CLA), a naturally occurring substance in food sources, occurs as mixtures of positional and geometrical isomers of octadecadienoate (18:2), and may inhibit colon tumorigenesis. It has been hypothesized that CLA can modulate cell proliferation and differentiation through the activation of peroxisome proliferator-activated receptors (PPARs), among which PPARgamma is involved in growth inhibition of transformed cells. The aim of the present study was to investigate whether the antiproliferative effects of CLA are mediated by its interaction with PPARgamma and APC/beta-catenin signalling pathway in human colon cancer cells. In CLA-treated caco-2 cells we found a remarkable increase in the expression of PPARgamma, which translocated into the nucleus, while PPARalpha and beta/delta protein levels were not affected. GW259662, a well known PPARgamma antagonist, blocked the increase in PPARgamma protein rate and abrogated some biological effects of CLA, as it restored the proliferative capability of the cells and ERK1/2 phosphorylation level. We demonstrated that CLA treatment determined the down-regulation of APC and c-myc proteins, but in this case the administration of the antagonist was not able to revert CLA effects. Furthermore, CLA induced a reorganization of E-cadherin and beta-catenin, as well as a redistribution of actin and tubulin filaments. Our data suggest that CLA may regulate PPARgamma expression by selectively acting as an agonist; however, the discrepancies in PPARgamma antagonist efficacy suggest the involvement of other pathways, independent of PPARgamma, in CLA antiproliferative activity.

Veterinary aspects and perspectives of nutrigenomics: a critical review

Nutrigenomics examines nutrient-gene interactions on a genome-wide scale. Increased dietary fat or higher non-esterified fatty acids (NEFA) from starvation-induced mobilisation may enhance hepatic oxidation and decrease esterification of fatty acids by reducing the expression of the fatty acid synthase gene. The key factors are the peroxisome proliferator-activated receptors (PPARs). Dietary carbohydrates--both independently and through insulin effect--influence the transcription of the fatty acid synthase gene. Oleic acid or n-3 fatty acids downregulate the expression of leptin, fatty acid synthase and lipoprotein lipase in retroperitoneal adipose tissue. Protein-rich diets entail a shortage of mRNA necessary for expression of the fatty acid synthase gene in the adipocytes. Conjugated linoleic acids (CLAs) are activators of PPAR and also induce apoptosis in adipocytes. Altered rumen microflora produces CLAs that are efficient inhibitors of milk fat synthesis in the mammary gland ('biohydrogenation theory'). Oral zinc or cadmium application enhances transcription rate in the metallothionein gene. Supplemental CLA in pig diets was found to decrease feed intake and body fat by activating PPARgamma-responsive genes in the adipose tissue. To prevent obesity and type II diabetes, the direct modulation of gene expression by nutrients is also possible. Nutrigenomics may help in the early diagnosis of genetically determined metabolic disorders and in designing individualised diets for companion animals.

Conjugated linoleic acid induces apoptosis of murine mammary tumor cells via Bcl-2 loss

Conjugated linoleic acid (CLA) is a powerful anticancer agent in a number of tumor model systems; however, its precise mechanism of action remains elusive. Here, we report that t10,c12 CLA, a component of synthetic CLA supplements, induced apoptosis and G1 arrest of p53 mutant TM4t murine mammary tumor cells. Furthermore, t10,c12-CLA induced a time- and concentration-dependent cleavage of caspases-3 and -9, and release of cytochrome c from mitochondria to cytosol. Levels of Bcl-2 protein were decreased both in total cellular lysates and in mitochondria after t10,c12-CLA treatment; however, there was no significant change in Bax or Bak. Overexpression of Bcl-2 attenuated apoptosis in response to t10,c12-CLA treatment. These results demonstrate that t10,c12-CLA triggers apoptosis of p53 mutant murine mammary tumor cells through the mitochondrial pathway by targeting Bcl-2.

Influence of conjugated linoleic acid isomers on the metastasis of colon cancer cells in vitro and in vivo

This study investigated the isomer-specific effects of cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) conjugated linoleic acid (CLA) on the metastasis of colon cancer cells in vitro and in vivo. Cell migration was examined by a Boyden chamber assay in SW480 cells. MMP-9 activity was monitored by gelatin zymography, and MMP-9 protein and mRNA levels were determined by Western blot and RT-PCR analysis, respectively, in SW480 cells. For the experimental metastasis, BALB/c mice were injected intravenously with CT-26 cells in the tail vein. Mice were fed a diet containing either no CLA or 0.1% c9,t11 or t10,c12 CLA for 4 weeks. In experimental metastasis, the numbers of pulmonary nodules were significantly lower in mice fed CLA isomers than in mice fed a control diet (P<.05). Results from the Boyden chamber assay revealed that c9,t11 CLA significantly inhibited cell migration (P<.05), whereas t10,c12 CLA had no effect on cell migration. The activity of MMP-9 was significantly inhibited by c9,t11 CLA (P<.05) but not by t10,c12 CLA. However, neither MMP-9 protein nor mRNA levels were altered by either of these CLA isomers. We have demonstrated that diets containing 0.1% c9,t11 and t10,c12 CLA were equally effective in inhibiting colon cancer cell metastasis in vivo. However, in vitro, only c9,t11 but not t10,c12 inhibited colon cancer cell migration and MMP-9 activity.

Induction of cell cycle arrest and apoptosis in HT-29 human colon cancer cells by the dietary compound luteolin

Luteolin is 3',4',5,7-tetrahydroxyflavone found in celery, green pepper, and perilla leaf that inhibits tumorigenesis in animal models. We examined luteolin-mediated regulation of cell cycle progression and apoptosis in the HT-29 human colon cancer cell line. Luteolin decreased DNA synthesis and viable HT-29 cell numbers in a concentration-dependent manner. It inhibited cyclin-dependent kinase (CDK)4 and CDK2 activity, resulting in G1 arrest with a concomitant decrease of phosphorylation of retinoblastoma protein. Activities of CDK4 and CDK2 decreased within 2 h after luteolin treatment, with a 38% decrease in CDK2 activity (P < 0.05) observed in cells treated with 40 micromol/l luteolin. Luteolin inhibited CDK2 activity in a cell-free system, suggesting that it directly inhibits CDK2. Cyclin D1 levels decreased after luteolin treatment, although no changes in expression of cyclin A, cyclin E, CDK4, or CDK2 were detected. Luteolin also promoted G2/M arrest at 24 h posttreatment by downregulating cyclin B1 expression and inhibiting cell division cycle (CDC)2 activity. Luteolin promoted apoptosis with increased activation of caspases 3, 7, and 9 and enhanced poly(ADP-ribose) polymerase cleavage and decreased expression of p21(CIP1/WAF1), survivin, Mcl-1, Bcl-x(L), and Mdm-2. Decreased expression of these key antiapoptotic proteins could contribute to the increase in p53-independent apoptosis that was observed in HT-29 cells. We demonstrate that luteolin promotes both cell cycle arrest and apoptosis in the HT-29 colon cancer cell line, providing insight about the mechanisms underlying its antitumorigenic activities.