Fatty acids and breast cancer: the role of stem cells

Cancer Stem Cells: Metabolic Characterization for Targeted Cancer Therapy

The subpopulation of cancer stem cells (CSCs) within tumor bulk are known for tumor recurrence and metastasis. CSCs show intrinsic resistance to conventional therapies and phenotypic plasticity within the tumor, which make these a difficult target for conventional therapies. CSCs have different metabolic phenotypes based on their needs as compared to the bulk cancer cells. CSCs show metabolic plasticity and constantly alter their metabolic state between glycolysis and oxidative metabolism (OXPHOS) to adapt to scarcity of nutrients and therapeutic stress. The metabolic characteristics of CSCs are distinct compared to non-CSCs and thus provide an opportunity to devise more effective strategies to target CSCs. Mechanism for metabolic switch in CSCs is still unravelled, however existing evidence suggests that tumor microenvironment affects the metabolic phenotype of cancer cells. Understanding CSCs metabolism may help in discovering new and effective clinical targets to prevent cancer relapse and metastasis. This review summarises the current knowledge of CSCs metabolism and highlights the potential targeted treatment strategies.

Coriolic Acid (13-(S)-Hydroxy-9Z, 11E-octadecadienoic Acid) from Glasswort (Salicornia herbacea L.) Suppresses Breast Cancer Stem Cell through the Regulation of c-Myc

Cancer stem cells have certain characteristics, such as self-renewal, differentiation, and drug resistance, which are related to tumor progression, maintenance, recurrence, and metastasis. In our study, we targeted breast cancer stem cells (BCSCs) using a natural compound, coriolic acid, from Salicornia herbacea L. This compound was isolated by mammosphere formation inhibition bioassay-guided fractionation and identified by using NMR spectroscopy and electrospray ionization mass spectrometry. Coriolic acid inhibited the formation of mammospheres and induced BCSC apoptosis. It also decreased the subpopulation of CD44^high/CD24^low cells, a cancer stem cell (CSC) phenotype, and specific genes related to CSCs, such as Nanog,Oct4, and CD44. Coriolic acid decreased the transcriptional and translational levels of the c-Myc gene, which is a CSC survival factor. These results indicated that coriolic acid could be a novel compound to target BCSCs via regulation of c-Myc.

n-3 Polyunsaturated Fatty Acid Amides: New Avenues in the Prevention and Treatment of Breast Cancer

Over the last decades a renewed interest in n−3 very long polyunsaturated fatty acids (PUFAs), derived mainly from fish oils in the human diet, has been observed because of their potential effects against cancer diseases, including breast carcinoma. These n−3 PUFAs mainly consist of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that, alone or in combination with anticancer agents, induce cell cycle arrest, autophagy, apoptosis, and tumor growth inhibition. A large number of molecular targets of n−3 PUFAs have been identified and multiple mechanisms appear to underlie their antineoplastic activities. Evidence exists that EPA and DHA also elicit anticancer effects by the conversion to their corresponding ethanolamide derivatives in cancer cells, by binding and activation of different receptors and distinct signaling pathways. Other conjugates with serotonin or dopamine have been found to exert anti-inflammatory activities in breast tumor microenvironment, indicating the importance of these compounds as modulators of tumor epithelial/stroma interplay. The objective of this review is to provide a general overview and an update of the current n−3 PUFA derivative research and to highlight intriguing aspects of the potential therapeutic benefits of these low-toxicity compounds in breast cancer treatment and care.

Breast cancer prevention in premenopausal women: role of the Mediterranean diet and its components

Breast cancer (BC) is a growing public health concern in most developed and developing countries. Since an increasing number of patients with BC are diagnosed before the menopause and premenopausal women show a more aggressive phenotype, there is consistent interest in promoting prevention strategies in order to reduce the incidence of BC in the premenopause. The Mediterranean diet (MD) has been reported to have beneficial effect in terms of cancer prevention. This healthy dietary pattern consists primarily of foods having important antioxidant properties along with a favourable fatty acid profile, all associated with a reduced risk of cancer. Due to the large variability in study subject characteristics, the protective role of the MD on BC still remains controversial and studies that have investigated the association between adherence to the MD and risk of BC in premenopausal women are fewer than those in postmenopausal women. In addition, the possibility that the beneficial effects of the MD are due to a single component or might more probably derive from the synergic effects of all components of the MD remains a scantly explored field. Considering the increased risk of recurrence and mortality rate of BC in premenopausal women as compared with postmenopausal women, the aim of the present report is to provide a general overview of the current evidence on the relationship between BC and the MD specifically in premenopausal women, and to emphasise the potential role of the MD as an effective measure to reduce the risk of developing BC in premenopausal women.

Metabolite profiling in sphere-forming cells from canine mammary adenocarcinoma cell lines using gas chromatography-mass spectrometry

Cancer consists of heterogeneous cells that contain a small population of cells that possess stem cell properties; these cells, referred to as cancer stem cells (CSCs) or tumor-initiating cells, are involved in tumor progression and metastasis. Using a sphere-forming assay, canine mammary CSCs were found to be similar to human breast CSCs. Metabolic reprogramming has been recognized as a hallmark of various cancers. However, the significance of cellular metabolism in CSCs remains unclear. The aim of this study was to define the metabolic characteristics of CSCs derived from canine mammary tumors and gain an understanding of the maintenance of stemness. We identified metabolite profiles of canine mammary adenocarcinoma cell lines using gas chromatography-mass spectrometry. Metabolites were extracted from both adherent and sphere-forming cells derived from three cell lines. Sphere-forming cells were separated from adherent cells using an orthogonal, partial least-squares discriminant analysis. Sphere-forming cells were found to contain high levels of the amino acids alanine, glycine and proline compared with adherent cells. They also had high levels of palmitoleate, palmitate and dihomo-gamma-linolenic acid compared with adherent cells. In a sphere-forming assay, palmitate increased the number of spheres for all cell lines. These results indicate that the sphere-forming cells derived from canine mammary adenocarcinoma cell lines have specific metabolic profiles that may be useful for the development of CSC-specific therapies targeting metabolic pathways and potential stemness biomarkers; these results also clarify the maintenance of stemness in canine mammary CSCs.

Metabolism-Based Therapeutic Strategies Targeting Cancer Stem Cells

Cancer heterogeneity constitutes the major source of disease progression and therapy failure. Tumors comprise functionally diverse subpopulations, with cancer stem cells (CSCs) as the source of this heterogeneity. Since these cells bear in vivo tumorigenicity and metastatic potential, survive chemotherapy and drive relapse, its elimination may be the only way to achieve long-term survival in patients. Thanks to the great advances in the field over the last few years, we know now that cellular metabolism and stemness are highly intertwined in normal development and cancer. Indeed, CSCs show distinct metabolic features as compared with their more differentiated progenies, though their dominant metabolic phenotype varies across tumor entities, patients and even subclones within a tumor. Following initial works focused on glucose metabolism, current studies have unveiled particularities of CSC metabolism in terms of redox state, lipid metabolism and use of alternative fuels, such as amino acids or ketone bodies. In this review, we describe the different metabolic phenotypes attributed to CSCs with special focus on metabolism-based therapeutic strategies tested in preclinical and clinical settings.

Decreased Oleic Acid and Marine n - 3 Polyunsaturated Fatty Acids in Tunisian Patients with Urothelial Bladder Cancer

Fatty acids (FAs) are thought to impact carcinogenesis by affecting cell signaling. A case-control study including 250 patients with urothelial bladder cancer (UBC) and 250 controls was conducted. Plasma FAs composition was assessed using capillary gas chromatography. Associations of individual and classes of FAs with UBC were controlled for the main risk factors for UBC. Plasma FAs profile was different in patients compared to controls. Higher levels (third tertile vs. first tertile) in palmitic acid (PA) [multi-adjusted OR (95% CI), 1.83 (1.14-2.92)], and n - 6:n - 3 FA ratio [4.13 (2.38-7.16)] were associated with increased risk for UBC [multi-adjusted OR (95% CI), 1.83 (1.14-2.92)]. In contrast, higher levels (third tertile vs. first tertile) in oleic [0.54 (0.34-0.86)], dihomo-γ-linolenic (DGLA) [0.47 (0.29-0.74)], eicosapentaenoic (EPA) [0.32 (0.19-0.52)], and docosahexaenoic (DHA) acids [0.33 (0.20-0.53)] were associated with lower risk for UBC. Although the study design does not allow proving causality, the findings suggest a possible protective role of oleic acid and marine n - 3 polyunsaturated FAs (PUFAs) against bladder carcinogenesis.

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 TRβ2). 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.

Epigenetic changes in cancer by Raman imaging, fluorescence imaging, AFM and scanning near-field optical microscopy (SNOM). Acetylation in normal and human cancer breast cells MCF10A, MCF7 and MDA-MB-231

This paper examines epigenetic changes in breast cancer by Raman imaging, fluorescence imaging, AFM and SNOM and discusses how they contribute to different aspects of tumourigenesis in malignant human breast epithelial cell lines MCF7 and MDA-MB-231 compared with non-malignant MCF10A cell lines. The paper focuses on information that can be extracted from Raman microscopy and Raman imaging for the biological material of nucleoli contained within the cell nucleus and lipid droplets within the cell cytoplasm. The biochemical composition of the nuclei and lipid droplets in the non-malignant and malignant human breast epithelial cell lines has been monitored. The potential of Raman microspectroscopy to monitor acetylation processes and a prognostic value of Raman biomarkers in breast cancer have been discussed.

N-3 Polyunsaturated Fatty Acids of Marine Origin and Multifocality in Human Breast Cancer

OBJECTIVE

The microenvironment of breast epithelial tissue may contribute to the clinical expression of breast cancer. Breast epithelial tissue, whether healthy or tumoral, is directly in contact with fat cells, which in turn could influence tumor multifocality. In this pilot study we investigated whether the fatty acid composition of breast adipose tissue differed according to breast cancer focality.

METHODS

Twenty-three consecutive women presenting with non-metastatic breast cancer underwent breast-imaging procedures including Magnetic Resonance Imaging prior to treatment. Breast adipose tissue specimens were collected during breast surgery. We established a biochemical profile of adipose tissue fatty acids by gas chromatography. We assessed whether there were differences according to breast cancer focality.

RESULTS

We found that decreased levels in breast adipose tissue of docosahexaenoic and eicosapentaenoic acids, the two main polyunsaturated n-3 fatty acids of marine origin, were associated with multifocality.

DISCUSSION

These differences in lipid content may contribute to mechanisms through which peritumoral adipose tissue fuels breast cancer multifocality.

The effects of omega-3 polyunsaturated Fatty Acid consumption on mammary carcinogenesis

The consumption of omega-3 polyunsaturated fatty acids (n-3 PUFA) is associated with a reduced risk of breast cancer. Studies in animals and in vitro have demonstrated mechanisms that could explain this apparent effect, but clinical and epidemiological studies have returned conflicting results on the practical benefits of dietary n-3 PUFA for prevention of breast cancer. Effects are often only significant within a population when comparing the highest n-3 PUFA consumption group to the lowest n-3 group or highest n-6 group. The beneficial effects of n-3 PUFA eicosapentaenoic and docosahexaenoic on the risk of breast cancer are dose dependent and are negatively affected by total n-6 consumption. The majority of the world population, including the most highly developed regions, consumes insufficient n-3 PUFA to significantly reduce breast cancer risk. This review discusses the physiological and dietary context in which reduction of breast cancer risk may occur, some proposed mechanisms of action and meaningful recommendations for consumption of n-3 PUFA in the diet of developed regions.

Elimination of ALDH+ breast tumor initiating cells by docosahexanoic acid and/or gamma tocotrienol through SHP-1 inhibition of Stat3 signaling

Study investigated the ability of docosahexaenoic acid (DHA) alone and in combination with gamma-tocotrienol (γT3) to eliminate aldehyde dehydrogenase positive (ALDH+) cells and to inhibit mammosphere formation, biomarker and functional assay for tumor initiating cells (TICs), respectively, in human triple negative breast cancer cells (TNBCs), and investigated possible mechanisms of action. DHA upregulated Src homology region 2 domain-containing protein tyrosine phosphatase-1 (SHP-1) protein levels and suppressed levels of phosphorylated signal transducer and activator of transcription-3 (pStat3) and its downstream mediators c-Myc, and cyclin D1. siRNA to SHP-1 enhanced the percentage of ALDH+ cells and Stat-3 signaling, as well as inhibited, in part, the ability of DHA to reduce the percentage of ALDH+ cells and Stat-3 signaling. γT3 alone and in combination with DHA reduced ALDH+ TNBCs, up-regulated SHP-1 protein levels, and suppressed Stat-3 signaling. Taken together, data demonstrate the anti-TIC potential of achievable concentrations of DHA alone as well as in combination with γT3.

The role of lipid droplets and adipocytes in cancer. Raman imaging of cell cultures: MCF10A, MCF7, and MDA-MB-231 compared to adipocytes in cancerous human breast tissue

We discussed the potential of lipid droplets in nonmalignant and malignant human breast epithelial cell lines as a prognostic marker in breast cancer.

n-3 polyunsaturated fatty acids and mechanisms to mitigate inflammatory paracrine signaling in obesity-associated breast cancer

Globally, the prevalence of obesity is increasing which subsequently increases the risk of the development of obesity-related chronic diseases. Low-grade chronic inflammation and dysregulated adipose tissue inflammatory mediator/adipokine secretion are well-established in obesity, and these factors increase the risk of developing inflammation-associated cancer. Breast cancer is of particular interest given that increased inflammation within the subcutaneous mammary adipose tissue depot can alter the local tissue inflammatory microenvironment such that it resembles that of obese visceral adipose tissue. Therefore, in obese women with breast cancer, increased inflammatory mediators both locally and systemically can perpetuate inflammation-associated pro-carcinogenic signaling pathways, thereby increasing disease severity. Herein, we discuss some of these inflammation-associated pro-carcinogenic mechanisms of the combined obese breast cancer phenotype and offer evidence that dietary long chain n-3 polyunsaturated fatty acids (PUFA) may have utility in mitigating the severity of obesity-associated inflammation and breast cancer.

Omega-3 fatty acids for the prevention of breast cancer: an update and state of the science

The quantity and makeup of dietary fat intake are known to impact human health. Use of Omega-3 (ω-3) polyunsaturated fatty acid (PUFA) supplements has gained increasing attention for a variety of purported health benefits, including cancer prevention. Preclinical evidence has been encouraging and recent studies have expanded our understanding of the mechanisms by which ω-3 PUFAs may protect against breast cancer. However, epidemiologic studies have yielded mixed results. Recent population studies have attempted to delineate factors that may influence the effects of ω-3 PUFAs such as total fat intake and the ratio of ω-3 to ω-6 PUFA intake. Several clinical trials, including some currently ongoing, are investigating novel strategies that favorably alter endogenous fatty acid profiles in an effort to develop clinically feasible prevention methods. Identification of well-defined subpopulations that are most likely to benefit from a targeted prevention approach will likely be crucial in this effort.

Association of HADHA expression with the risk of breast cancer: targeted subset analysis and meta-analysis of microarray data

Background

The role of n-3 fatty acids in prevention of breast cancer is well recognized, but the underlying molecular mechanisms are still unclear. In view of the growing need for early detection of breast cancer, Graham et al. (2010) studied the microarray gene expression in histologically normal epithelium of subjects with or without breast cancer. We conducted a secondary analysis of this dataset with a focus on the genes (n = 47) involved in fat and lipid metabolism. We used stepwise multivariate logistic regression analyses, volcano plots and false discovery rates for association analyses. We also conducted meta-analyses of other microarray studies using random effects models for three outcomes--risk of breast cancer (380 breast cancer patients and 240 normal subjects), risk of metastasis (430 metastatic compared to 1104 non-metastatic breast cancers) and risk of recurrence (484 recurring versus 890 non-recurring breast cancers).

Results

The HADHA gene [hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase (trifunctional protein), alpha subunit] was significantly under-expressed in breast cancer; more so in those with estrogen receptor-negative status. Our meta-analysis showed an 18.4%-26% reduction in HADHA expression in breast cancer. Also, there was an inconclusive but consistent under-expression of HADHA in subjects with metastatic and recurring breast cancers.

Conclusions

Involvement of mitochondria and the mitochondrial trifunctional protein (encoded by HADHA gene) in breast carcinogenesis is known. Our results lend additional support to the possibility of this involvement. Further, our results suggest that targeted subset analysis of large genome-based datasets can provide interesting association signals.