Mammary tumour development is dose-dependently inhibited by n-3 polyunsaturated fatty acids in the MMTV-neu(ndl)-YD5 transgenic mouse model

Influence of Olive Oil and Its Components on Breast Cancer: Molecular Mechanisms

Breast cancer is the most frequent malignant neoplasia and a leading cause of mortality in women worldwide. The Mediterranean diet has been proposed as a healthy dietary pattern with protective effects in several chronic diseases, including breast cancer. This diet is characterized by the consumption of abundant plant foods and olive oil as the principal source of fat, which is considered one of the main components with potential antioxidant, anti-inflammatory and anticancer effects. Extra-virgin olive oil (EVOO) has several bioactive compounds, mainly including monounsaturated fatty acids, triterpenes and polyphenols, such as phenolic alcohols (e.g., hydroxytyrosol), secoiridoids (e.g., oleuropein and oleocanthal), lignans (e.g., pinoresinol) or flavonoids (e.g., luteolin). While epidemiological evidence is still limited, experimental in vivo and in vitro data have shown a protective effect of this oil and its compounds on mammary carcinogenesis. Such effects account through complex and multiple mechanisms, including changes in epigenetics, transcriptome and protein expression that modulate several signaling pathways. Molecular targets of EVOO compounds have a role in the acquisition of cancer hallmarks. Although further research is needed to elucidate their beneficial effects on human prevention and progression of the disease, evidence points to EVOO in the context of the Mediterranean diet as a heathy choice, while EVOO components may be promising adjuvants in anticancer strategies.

Fish oil supplementation increases expression of mammary tumor apoptosis mediators and reduces inflammation in an obesity-associated HER-2 breast cancer model

Obesity is associated with inflammation and has been shown to increase breast cancer severity. The objective of this study was to examine the effect of fish oil (FO) supplementation in obesity-associated mammary tumorigenesis in the MMTV-neu(ndl)-YD5 mouse model of human epidermal growth factor receptor-2 positive BC. Female mice were fed one of three diets for 16 weeks: i) high fat diet [HF, % kacl: 41.2% lard, 18.7% corn oil (CO)], ii) an isocaloric HF plus menhaden FO diet (HF+FO, % kcal: 41.2 lard, 13.4% CO, 5.3% FO), iii) low fat diet (LF, % kcal: 4.7% lard, 6% CO). HF mice had increased body weight, visceral adipose weight and serum hormone concentrations (increased leptin and resistin; decreased adiponectin) versus LF, which was attenuated in the HF+FO group versus HF (P<.05). Compared to HF, tumor onset was delayed in HF+FO and LF mice (P<0.05). Compared to HF, HF+FO reduced mammary tumor multiplicity (-27%), tumor weight (-46%) and total tumor volume (-50%) (P<0.05). Additionally, HF+FO reduced mammary tumor multiplicity (-33%), tumor weight (-39%) and total tumor volume (-60%) versus LF. HF+FO improved mammary tumor apoptosis status with increased expression of pro-apoptotic Bad and decreased expression of anti-apoptotic Bcl-xLmediators versus HF (P<0.05). Additionally, HF+FO decreased tumor protein expression of activated Akt, NFκB p65 and STAT3, versus HF (P<0.05). Tumor mRNA expression of inflammatory mediators TNFα, IL-6 and leptin were reduced in HF+FO, whereas IL-10 expression was increased compared to HF (P<0.05). Collectively these results demonstrate the efficacy of FO supplementation for improving obesity-associated breast cancer outcomes.

Total long-chain polyunsaturated n-3 fatty acids level is an independent predictive factor of breast cancer multifocality in women with positive hormone-receptors tumors

In a previous pilot study, we showed that polyunsaturated n-3 fatty acids of breast adipose tissues were associated with breast cancer multifocality. In the present study, we investigated biochemical, clinical and histological factors associated with breast cancer focality in a large cohort of women with positive hormone-receptors tumors. One hundred sixty-one consecutive women presenting with positive hormone-receptors breast cancer underwent breast-imaging procedures including a Magnetic Resonance Imaging prior to treatment. Breast adipose tissue specimens were collected during surgery of tumors. A biochemical profile of breast adipose tissue fatty acids was established by gas chromatography. Clinicopathologic characteristics were correlated with multifocality. We assessed whether these factors were predictive of breast cancer focality. We found that tumor size (OR = 1.06 95%CI [1.02-1.09], p < 0.001) and decreased levels in breast adipose tissue of long-chain polyunsaturated n-3 fatty acids (OR = 0.11 95%CI [0.01-0.98], p = 0.03), were independent predictive factors of multifocality. Low levels of long chain polyunsaturated n-3 fatty acids in breast adipose tissue appear to contribute to breast cancer multifocality. The present results reinforce the link between dietary habits and breast cancer clinical presentation.

Mechanistic Targets and Nutritionally Relevant Intervention Strategies to Break Obesity-Breast Cancer Links

The worldwide prevalence of overweight and obesity has tripled since 1975. In the United States, the percentage of adults who are obese exceeds 42.5%. Individuals with obesity often display multiple metabolic perturbations, such as insulin resistance and persistent inflammation, which can suppress the immune system. These alterations in homeostatic mechanisms underlie the clinical parameters of metabolic syndrome, an established risk factor for many cancers, including breast cancer. Within the growth-promoting, proinflammatory milieu of the obese state, crosstalk between adipocytes, immune cells and breast epithelial cells occurs via obesity-associated hormones, angiogenic factors, cytokines, and other mediators that can enhance breast cancer risk and/or progression. This review synthesizes evidence on the biological mechanisms underlying obesity-breast cancer links, with emphasis on emerging mechanism-based interventions in the context of nutrition, using modifiable elements of diet alone or paired with physical activity, to reduce the burden of obesity on breast cancer.

The Role of PPARγ Ligands in Breast Cancer: From Basic Research to Clinical Studies

Peroxisome proliferator-activated receptor gamma (PPARγ), belonging to the nuclear receptor superfamily, is a ligand-dependent transcription factor involved in a variety of pathophysiological conditions such as inflammation, metabolic disorders, cardiovascular disease, and cancers. In this latter context, PPARγ is expressed in many tumors including breast cancer, and its function upon binding of ligands has been linked to the tumor development, progression, and metastasis. Over the last decade, much research has focused on the potential of natural agonists for PPARγ including fatty acids and prostanoids that act as weak ligands compared to the strong and synthetic PPARγ agonists such as thiazolidinedione drugs. Both natural and synthetic compounds have been implicated in the negative regulation of breast cancer growth and progression. The aim of the present review is to summarize the role of PPARγ activation in breast cancer focusing on the underlying cellular and molecular mechanisms involved in the regulation of cell proliferation, cell cycle, and cell death, in the modulation of motility and invasion as well as in the cross-talk with other different signaling pathways. Besides, we also provide an overview of the in vivo breast cancer models and clinical studies. The therapeutic effects of natural and synthetic PPARγ ligands, as antineoplastic agents, represent a fascinating and clinically a potential translatable area of research with regards to the battle against cancer.

Pubertal mammary development as a "susceptibility window" for breast cancer disparity

Factors such as socioeconomic status, age at menarche and childbearing patterns are components that have been shown to influence mammary gland development and establish breast cancer disparity. Pubertal mammary gland development is selected as the focus of this review, as it is identified as a "window of susceptibility" for breast cancer risk and disparity. Here we recognize non-Hispanic White, African American, and Asian American women as the focus of breast cancer disparity, in conjunction with diets associated with changes in breast cancer risk. Diets consisting of high fat, N-3 polyunsaturated fatty acids, N-6 polyunsaturated fatty acids, as well as obesity and the Western diet have shown to lead to changes in pubertal mammary gland development in mammalian models, therefore increasing the risk of breast cancer and breast cancer disparity. While limited intervention strategies are offered to adolescents to mitigate development changes and breast cancer risk, the prominent solution to closing the disparity among the selected population is to foster lifestyle changes that avoid the deleterious effects of unhealthy diets.

Lifelong n-3 Polyunsaturated Fatty Acid Exposure Modulates Size of Mammary Epithelial Cell Populations and Expression of Caveolae Resident Proteins in Fat-1 Mice

Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been associated with reduced breast cancer risk; however, the exact mechanism remains elusive. Female wildtype (WT) and fat-1 mice were fed a 10% safflower diet until 6 weeks of age. Mammary gland epithelial cells (EC) were isolated and EC populations were determined by CD24 surface expression. Fat-1 mice expressed 65%, 20%, and 15% while WT mice expressed 65%, 26% and 9% for non-, myo- and luminal ECs, respectively. The luminal EC population was significantly greater in fat-1 mice (p ≤ 0.05), while the total number of mammary ECs were similar between groups (p = 0.79). Caveolae was isolated from ECs and Her-2/neu, ER-α and cav-1 protein expression was determined by Western blotting. Fat-1 mice had a two-fold greater ER-α (p ≤ 0.05) and a 1.5-fold greater cav-1 (p ≤ 0.05) expression than WT with a similar amount of Her-2/neu protein (p = 0.990) between groups. Overall, this study provides novel mechanistic evidence by which n-3 PUFA modifies early mammary gland development that may potentially reduce breast cancer risk later in life.

Dietary polyunsaturated fatty acids modulate adipose secretome and is associated with changes in mammary epithelial stem cell self-renewal

Chronic low-grade adipose inflammation, characterized by aberrant adipokine production and pro-inflammatory macrophage activation/polarization is associated with increased risk of breast cancer. Adipocyte fatty acid composition is influenced by dietary availability and may regulate adipokine secretion and adipose inflammation. After feeding F344 rats for 20 weeks with a Western diet or a fish oil-supplemented diet, we cultured primary rat adipose tissue in a three-dimensional explant culture and collected the conditioned medium. The rat adipose tissue secretome was assayed using the Proteome Profiler Cytokine XL Array, and adipose tissue macrophage polarization (M1/M2 ratio) was assessed using the iNOS/ARG1 ratio. We then assessed the adipokine's effects upon stem cell self-renewal using primary human mammospheres from normal breast mammoplasty tissue. Adipose from rats fed the fish oil diet had an ω-3:ω-6 fatty acid ratio of 0.28 compared to 0.04 in Western diet rats. The adipokine profile from the fish oil-fed rats was shifted toward adipokines associated with reduced inflammation compared to the rats fed the Western diet. The M1/M2 macrophage ratio decreased by 50% in adipose of fish oil-fed rats compared to that from rats fed the Western diet. Conditioned media from rats fed the high ω-6 Western diet increased stem cell self-renewal by 62%±9% (X¯%±SD) above baseline compared to only an 11%±11% increase with the fish oil rat adipose. Modulating the adipokine secretome with dietary interventions therefore may alter stromal-epithelial signaling that plays a role in controlling mammary stem cell self-renewal.

Marine fish oil is more potent than plant-based n-3 polyunsaturated fatty acids in the prevention of mammary tumors

Marine-derived n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been shown to inhibit mammary carcinogenesis. However, evidence regarding plant-based α-linolenic acid (ALA), the major n-3 PUFA in the Western diet, remains equivocal. The objective of this study was to examine the effect of lifelong exposure to plant- or marine-derived n-3 PUFAs on pubertal mammary gland and tumor development in MMTV-neu(ndl)-YD5 mice. It is hypothesized that lifelong exposure to n-3 PUFA reduces terminal end buds during puberty leading to delayed tumor onset, volume and multiplicity. It is further hypothesized that plant-derived n-3 PUFAs will exert dose-dependent effects. Harems of MMTV-FVB males were bred with wild-type females and fed either a (1) 10% safflower (10% SF, n-6 PUFA, control), (2) 10% flaxseed (10% FS), (3) 7% safflower plus 3% flaxseed (3% FS) or (4) 7% safflower plus 3% menhaden (3% FO) diet. Female offspring were maintained on parental diets. Compared to SF, 10% FS and 3% FO reduced (P<.05) terminal end buds at 6 weeks and tumor volume and multiplicity at 20 weeks. A dose-dependent reduction of tumor volume and multiplicity was observed in mice fed 3% and 10% FS. Antitumorigenic effects were associated with altered HER2, pHER-2, pAkt and Ki-67 protein expression. Compared to 10% SF, 3% FO significantly down-regulated expression of genes involved in eicosanoid synthesis and inflammation. From this, it can be estimated that ALA was 1/8 as potent as EPA+DHA. Thus, marine-derived n-3 PUFAs have greater potency versus plant-based n-3 PUFAs.

Role of n-3 Polyunsaturated Fatty Acids and Exercise in Breast Cancer Prevention: Identifying Common Targets

Diet and exercise are recognized as important lifestyle factors that significantly influence breast cancer risk. In particular, dietary n-3 polyunsaturated fatty acids (PUFAs) have been shown to play an important role in breast cancer prevention. Growing evidence also demonstrates a role for exercise in cancer and chronic disease prevention. However, the potential synergistic effect of n-3 PUFA intake and exercise is yet to be determined. This review explores targets for breast cancer prevention that are common between n-3 PUFA intake and exercise and that may be important study outcomes for future research investigating the combined effect of n-3 PUFA intake and exercise. These lines of evidence highlight potential new avenues for research and strategies for breast cancer prevention.

Resolvins and omega three polyunsaturated fatty acids: Clinical implications in inflammatory diseases and cancer

Inflammation is a central process in several disorders and contributes to cancer progression. Inflammation involves a complex cascade of pro-inflammatory and anti-inflammatory signaling events with protein and lipid mediators. Recent advances in lipid detection have revealed the importance of lipid mediators in inflammation. Omega three polyunsaturated fatty acids (ω-3 PUFA) are found naturally in fish oil and have been extensively studied in multiple inflammatory diseases with improved outcomes. Resolvins are thought to be the active metabolites of ω-3 PUFA, and are responsible for facilitating the resolving phase of acute inflammation. Clinically, resolvins have been associated with resolution of acute kidney injury and acute lung injury, micro and macro vascular response to injury, and inhibition of microglia-activated inflammation in neurodegenerative disorders. In addition to inflammatory diseases, ω-3 PUFA and resolvins appear to modulate cancer progression. ω-3 PUFA intake has been associated with reduced inflammation in colorectal cancer, and favorable phenotype in breast cancer. Resolvins offer promising therapeutic potential as they may modulate inflammation with minimal side-effects, in contrast to currently available anti-inflammatory medications. This review describes the roles of ω-3 PUFA and resolvins in the inflammatory cascade, various inflammatory diseases, and specific cancers. Additionally, it will discuss the clinical therapeutic potential of resolvins as targets in inflammatory diseases and cancers.

Omega-3/omega-6 fatty acid ratios in different phospholipid classes and depressive symptoms in coronary artery disease patients

Depressive symptoms are highly incident among coronary artery disease (CAD) patients and increase mortality. Reduced ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (omega-3 fatty acids) to arachidonic acid (AA, omega-6 fatty acid) concentrations have been linked with depressive symptoms in CAD. It remains unclear whether depressive symptoms are differentially associated with that ratio in different phospholipid classes, and this may have mechanistic implications. This study investigated associations between depressive symptoms in CAD patients and the EPA+DHA to AA ratio in the major phospholipid classes. This was a cross-sectional study of stable CAD patients. Sociodemographic, medical, medication, and cardiopulmonary fitness data were collected from each patient. Each patient was assessed for depressive symptoms using the 17-item Hamilton Depression Rating Scale (HAM-D). The percentage of EPA, DHA, and AA in each erythrocyte phospholipid class was determined using gas chromatography from fasting blood. Relationships between EPA+DHA to AA ratios and depressive symptoms were assessed using linear regression and were corrected for multiple comparisons. Seventy-six CAD patients were included (age=61.9 ± 8.5, 74% male, HAM-D=7.2 ± 5.9). In a backward elimination linear regression model, lower EPA+DHA to AA in erythrocyte phosphatidylinositol (B=-12.71, β=-0.33, p<.01) and sphingomyelin (B=-2.52, β=-0.37, p<.01) was associated with greater depressive symptom severity, independently of other known predictors. Other phospholipid classes were not associated with depressive symptoms. In conclusion, the relationship between EPA+DHA to AA ratios and depressive symptoms in CAD may not be consistent across phospholipid classes. Continued investigation of these potentially differential relationships may clarify underlying disease mechanisms.

Cancer Risk and Eicosanoid Production: Interaction between the Protective Effect of Long Chain Omega-3 Polyunsaturated Fatty Acid Intake and Genotype

Dietary inclusion of fish and fish supplements as a means to improve cancer prognosis and prevent tumour growth is largely controversial. Long chain omega-3 polyunsaturated fatty acids (LCn-3 PUFA), eicosapentaenoic acid and docosahexaenoic acid, may modulate the production of inflammatory eicosanoids, thereby influencing local inflammatory status, which is important in cancer development. Although in vitro studies have demonstrated inhibition of tumour cell growth and proliferation by LCn-3 PUFA, results from human studies have been mainly inconsistent. Genes involved in the desaturation of fatty acids, as well as the genes encoding enzymes responsible for eicosanoid production, are known to be implicated in tumour development. This review discusses the current evidence for an interaction between genetic polymorphisms and dietary LCn-3 PUFA in the risk for breast, prostate and colorectal cancers, in regards to inflammation and eicosanoid synthesis.

α-linolenic acid and docosahexaenoic acid, alone and combined with trastuzumab, reduce HER2-overexpressing breast cancer cell growth but differentially regulate HER2 signaling pathways

BACKGROUND

Diets rich in the n-3 fatty acid alpha-linolenic acid (ALA) have been shown to reduce breast tumor growth, enhance the effectiveness of the HER2-targeted drug trastuzumab (TRAS) and reduce HER2 signaling in mouse models. It is unclear whether this is due to direct effects of ALA or due to its long-chain n-3 fatty acids metabolites including docosahexaenoic acid (DHA).

METHODS

The ability of HER2-overexpressing BT-474 human breast cancer cells to convert ALA to long-chain n-3 fatty acids was determined by measurement of phospholipid fatty acids by gas chromatography following treatment with 100 μM ALA. The effects of 96 h treatment with ALA or DHA, at serum levels seen in mice (50-100 μM), alone and combined with TRAS (10 μg/ml), on BT-474 cell growth measured by trypan blue exclusion, apoptosis measured by flow cytometric analysis of Annexin-V/7-AAD stained cells (ALA and TRAS treatment only) and protein biomarkers HER2 signaling measured by western blot were determined.

RESULTS

ALA-treated BT-474 cells had higher phospholipid ALA but no increase in downstream n-3 metabolites including DHA. Both ALA and DHA reduced cell growth with and without TRAS. ALA had no effect on apoptosis. ALA and DHA showed opposite effects on Akt and MAPK phosphorylation; ALA increased and DHA decreased phosphorylation.

CONCLUSIONS

Together these data suggest that, while both ALA and its DHA metabolite can reduce HER2-overexpressing breast cancer growth with and without TRAS, they demonstrate for the first time that DHA is responsible for the effects of ALA-rich diets on HER2 signaling pathways.

The role of n-3 polyunsaturated fatty acids in the prevention and treatment of breast cancer

Breast cancer (BC) is the most common cancer among women worldwide. Dietary fatty acids, especially n-3 polyunsaturated fatty acids (PUFA), are believed to play a role in reducing BC risk. Evidence has shown that fish consumption or intake of long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial for inhibiting mammary carcinogenesis. The evidence regarding α-linolenic acid (ALA), however, remains equivocal. It is essential to clarify the relation between ALA and cancer since ALA is the principal source of n-3 PUFA in the Western diet and the conversion of ALA to EPA and DHA is not efficient in humans. In addition, the specific anticancer roles of individual n-3 PUFA, alone, have not yet been identified. Therefore, the present review evaluates ALA, EPA and DHA consumed individually as well as in n-3 PUFA mixtures. Also, their role in the prevention of BC and potential anticancer mechanisms of action are examined. Overall, this review suggests that each n-3 PUFA has promising anticancer effects and warrants further research.

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.