PPAR Receptors Expressed from Vectors Containing CMV Promoter Can Enhance Self-Transcription in the Presence of Fatty Acids from CLA-Enriched Egg Yolks-A Novel Method for Studies of PPAR Ligands.

PPAR receptors are ligand-dependent transcription factors activated in response to various small lipophilic ligands controlling the expression of different genes involved in cellular differentiation, development, metabolism, and tumorigenesis. Unexpectedly, our previous studies have shown that single plasmid-based expression of PPARs under the control of CMV promoter/enhancer was significantly elevated in the presence of PPAR agonists. Here we show that the PPAR reporters controlled by the CMV promoter/enhancer, that was shown to contain three internal non-canonical PPRE elements, can be used as a fast screening system for more effective PPAR ligands. This model allowed us to confirm our previous results indicating that fatty acids of CLA-enriched egg yolks (EFA-CLAs) are efficient PPAR ligands that can specifically upregulate the expression of PPARα and PPARγ leading to downregulation of MCF-7 cancer cell proliferation. We also show that synthetic cis9,trans11CLA is more effective in transactivation of PPARγ, while trans10,cis12CLA of PPARα receptor indicating the selectivity of the CLA isomers. This report presents a novel, fast, and reliable strategy for simple testing of PPAR ligands using PPAR expressing plasmids containing the CMV promoter/enhancer that can trigger the positive feedback loop of PPAR self-transcription in the presence of PPAR ligands.

Fatty Acids of CLA-enriched Egg Yolks Can Induce Mitochondrial Pathway of Apoptosis in MCF-7 Breast Cancer Cells.

BACKGROUND: Fatty acids from conjugated linoleic acid (CLA)-enriched egg yolk suppressed the viability of the MCF-7 cancer line more effectively than non-enriched egg yolk. Herein we aimed to determine the molecular mechanisms by analysing the expression and activation of proteins involved in cellular stress and apoptosis signaling. MATERIALS AND METHODS: Forty-eight Isa Brown laying hens (26-week-old) were fed a fortified (0.75% CLA) or a control diet (0% CLA) for 4 months. Collected eggs were used to obtain CLA-enriched (EFA-CLA) or non-enriched (EFA) fatty acid extracts for the treatment of the MCF-7 cancer cell line. Protein levels were analysed by PathScan® Stress and Apoptosis Signalling Antibody Array and western blot method. RESULTS: Treatment with EFA-CLA led to activation of caspase signalling as main effector of apoptosis. It also increased levels of pro-apoptotic B-cell lymphoma 2 family proteins as well as promoted the release of cytochrome c, second mitochondria-derived activator of caspase and mitochondrial serine protease from mitochondria to the cytoplasm. EFA-CLA increased levels of tumour protein 53 and mothers against decapentaplegic homolog 2 tumour suppressors, and activated p38 mitogen-activated protein kinases and stress-activated protein kinase/c-Jun NH2-terminal kinase proteins. Finally, treatment down-regulated anti-apoptotic extracellular signal-regulated protein kinases 1 and 2, RAC-alpha serine/threonine-protein kinase, heat-shock protein 27, inhibitor of nuclear factor κß, transforming growth factor beta-activated kinase 1 and survivin proteins. CONCLUSION: Taken together, our results suggest that activation of the mitochondrial apoptotic pathway may be a potential mechanism of EFA-CLA action.

Antitumor Properties of CLA-Enriched Food Products.

In this manuscript, we reviewed the available literature on the effects of conjugated linoleic acid (CLA)-enriched food products, including meat, dairy products, and eggs on cancer, both in vivo and in vitro. Based on our own studies on CLA-enriched eggs, we also identified potential molecular mechanisms by which such products may act on cancer cells. We propose the mitochondrial apoptosis pathway as mainly accountable for the reduction of cancer cells viability. Our hypothesis is supported by observed changes in expression of genes associated with downregulation of AKT/mTOR signalling pathway. In addition, we propose that CLA-enriched food products can act as peroxisome proliferator-activated receptors (PPAR) ligands showing predominately an agonist effect on PPAR isoforms.

The effect of "NutramilTM Complex," food for special medical purpose, on breast and prostate carcinoma cells.

NutramilTM Complex is a multicomponent food product that meets the requirements of a food for special medical purpose. As a complete, high-energy diet it consists of properly balanced nutrients, vitamins and minerals. The aim of this study was to assess the effect of NutramilTM Complex on breast and prostate carcinoma cells. Our results showed that NutramilTM Complex reduced the viability and proliferation of breast and prostate cancer cells and that this process was associated with the induction of apoptosis via activation of caspase signalling. Data showed elevated levels of p53 tumour suppressor, up-regulation of p38 MAPK and SAPK / JNK proteins and downregulation of anti-apoptotic ERK1/2, AKT1 and HSP27. Treatment with NutramilTM Complex also affected the expression of the BCL2 family genes. Results also showed down-regulation of anti-apoptotic BCL-2 and up-regulation of pro-apoptotic members such as BAX, BAD, BID. In addition, we also observed regulation of many other genes, including Iκßα, Chk1 and Chk2, associated with apoptotic events. Taken together, our results suggest activation of the mitochondrial apoptotic pathway as most likely mechanism of anti-carcinogenic activity of NutramilTM Complex.

Fatty Acids of CLA-Enriched Egg Yolks Can Induce Transcriptional Activation of Peroxisome Proliferator-Activated Receptors in MCF-7 Breast Cancer Cells.

In our previous study, we showed that fatty acids from CLA-enriched egg yolks (EFA-CLA) reduced the proliferation of breast cancer cells; however, the molecular mechanisms of their action remain unknown. In the current study, we used MCF-7 breast cancer cell line to determine the effect of EFA-CLA, as potential ligands for peroxisome proliferator-activated receptors (PPARs), on identified in silico PPAR-responsive genes: BCAR3, TCF20, WT1, ZNF621, and THRB (transcript TRß2). Our results showed that EFA-CLA act as PPAR ligands with agonistic activity for all PPAR isoforms, with the highest specificity towards PPARγ. In conclusion, we propose that EFA-CLA-mediated regulation of PPAR-responsive genes is most likely facilitated by cis9,trans11CLA isomer incorporated in egg yolk. Notably, EFA-CLA activated PPAR more efficiently than nonenriched FA as well as synthetic CLA isomers. We also propose that this regulation, at least in part, can be responsible for the observed reduction in the proliferation of MCF-7 cells treated with EFA-CLA.

Fatty acid extract from CLA-enriched egg yolks can mediate transcriptome reprogramming of MCF-7 cancer cells to prevent their growth and proliferation.

BACKGROUND: Our previous study showed that fatty acids extract obtained from CLA-enriched egg yolks (EFA-CLA) suppressed the viability of MCF-7 cancer cell line more effectively than extract from non-enriched egg yolks (EFA). In this study, we analysed the effect of EFA-CLA and EFA on transcriptome profile of MCF-7 cells by applying the whole Human Genome Microarray technology. RESULTS: We found that EFA-CLA and EFA treated cells differentially regulated genes involved in cancer development and progression. EFA-CLA, compared to EFA, positively increased the mRNA expression of TSC2 and PTEN tumor suppressors as well as decreased the expression of NOTCH1, AGPS, GNA12, STAT3, UCP2, HIGD2A, HIF1A, PPKAR1A oncogenes. CONCLUSIONS: We show for the first time that EFA-CLA can regulate genes engaged in AKT/mTOR pathway and inhibiting cell cycle progression. The observed results are most likely achieved by the combined effect of both: incorporated CLA isomers and other fatty acids in eggs organically modified through hens' diet. Our results suggest that CLA-enriched eggs could be easily available food products with a potential of a cancer chemopreventive agent.

Erratum to: Fatty acid extract from CLA-enriched egg yolks can mediate transcriptome reprogramming of MCF-7 cancer cells to prevent their growth and proliferation.

[This corrects the article DOI: 10.1186/s12263-016-0537-z.].

Transcriptome Profiling of Caco-2 Cancer Cell Line following Treatment with Extracts from Iodine-Biofortified Lettuce (Lactuca sativa L.).

Although iodization of salt is the most common method used to obtain iodine-enriched food, iodine deficiency disorders are still a global health problem and profoundly affect the quality of human life. Iodine is required for the synthesis of thyroid hormones, which are crucial regulators of human metabolism, cell growth, proliferation, apoptosis and have been reported to be involved in carcinogenesis. In this study, for the first time, we evaluated the effect of iodine-biofortified lettuce on transcriptomic profile of Caco-2 cancer cell line by applying the Whole Human Genome Microarray assay. We showed 1326 differentially expressed Caco-2 transcripts after treatment with iodine-biofortified (BFL) and non-fortified (NFL) lettuce extracts. We analysed pathways, molecular functions, biological processes and protein classes based on comparison between BFL and NFL specific genes. Iodine, which was expected to act as a free ion (KI-NFL) or at least in part to be incorporated into lettuce macromolecules (BFL), differently regulated pathways of numerous transcription factors leading to different cellular effects. In this study we showed the inhibition of Caco-2 cells proliferation after treatment with BFL, but not potassium iodide (KI), and BFL-mediated induction of mitochondrial apoptosis and/or cell differentiation. Our results showed that iodine-biofortified plants can be effectively used by cells as an alternative source of this trace element. Moreover, the observed differences in action of both iodine sources may suggest a potential of BFL in cancer treatment.