Fish consumption and breast cancer risk: an ecological study

Personalized breast cancer onset prediction from lifestyle and health history information

We propose a method to predict when a woman will develop breast cancer (BCa) from her lifestyle and health history features. To address this objective, we use data from the Alberta's Tomorrow Project of 18,288 women to train Individual Survival Distribution (ISD) models to predict an individual's Breast-Cancer-Onset (BCaO) probability curve. We show that our three-step approach-(1) filling missing data with multiple imputations by chained equations, followed by (2) feature selection with the multivariate Cox method, and finally, (3) using MTLR to learn an ISD model-produced the model with the smallest L1-Hinge loss among all calibrated models with comparable C-index. We also identified 7 actionable lifestyle features that a woman can modify and illustrate how this model can predict the quantitative effects of those changes-suggesting how much each will potentially extend her BCa-free time. We anticipate this approach could be used to identify appropriate interventions for individuals with a higher likelihood of developing BCa in their lifetime.

Resolving the omega-3 methyl resonance with long echo time magnetic resonance spectroscopy in mouse adipose tissue at 9.4 T

Tissue omega-3 (ω-3) content is biologically important to disease; however, its quantification with magnetic resonance spectroscopy in vivo is challenging due to its low concentration. In addition, the ω-3 methyl resonance (≈ 0.98 ppm) overlaps that of the non-ω-3 (≈ 0.90 ppm), even at 9.4 T. We demonstrate that a Point-RESolved Spectroscopy (PRESS) sequence with an echo time (TE) of 109 ms resolves the ω-3 and non-ω-3 methyl peaks at 9.4 T. Sequence efficacy was verified on five oils with differing ω-3 fat content; the ω-3 content obtained correlated with that measured using 16.5 T NMR (R² = 0.97). The PRESS sequence was also applied to measure ω-3 content in visceral adipose tissue of three different groups (all n = 3) of mice, each of which were fed a different 20% w/w fat diet. The fat portion of the diet consisted of low (1.4%), medium (9.0%) or high (16.4%) ω-3 fat. The sequence was also applied to a control mouse fed a standard chow diet (5.6% w/w fat, which was 5.9% ω-3). Gas chromatography (GC) analysis of excised tissue was performed for each mouse. The ω-3 fat content obtained with the PRESS sequence correlated with the GC measures (R² = 0.96). Apparent T₂ times of methyl protons were assessed by obtaining spectra from the oils and another group of four mice (fed the high ω-3 diet) with TE values of 109 and 399 ms. Peak areas were fit to a mono-exponentially decaying function and the apparent T₂ values of the ω-3 and non-ω-3 methyl protons were 906 ± 148 and 398 ± 78 ms, respectively, in the oils. In mice, the values were 410 ± 68 and 283 ± 57 ms for ω-3 and non-ω-3 fats, respectively.

Phenotypic Characteristics and Fatty Acid Composition of Seeds from Different Herbaceous Peony Species Native to China

Herbaceous peony has been widely cultivated in China due to its substantial ornamental and medicinal value. In the present study, the phenotypic characteristics, total fatty acid (FA) content, and nine FA compositions of herbaceous peony seeds from 14 populations belonging to six species and one subspecies were determined by normal test and gas chromatography/mass spectrometry (GC/MS). The results showed that the phenotypic characteristics of seeds varied dramatically among species. The concentrations of five major FAs in seed oils were as follows: linoleic acid (173.95-236.51 μg/mg), linolenic acid (227.82-302.71 μg/mg), oleic acid (135.32-208.81 μg/mg), stearic acid (6.52-11.7 μg/mg), and palmitic acid (30.67-47.64 μg/mg). Correlation analysis demonstrated that oleic acid had the highest partial correlation coefficient with total FAs and might be applied to develop a model of phenotypic characteristics. FAs were significantly influenced by the following environmental factors: latitude, elevation, and annual average temperature. Based on the FA levels in the seed oils, clustering analysis divided 14 populations into two clusters. It was found that the average contents of oleic acid, linoleic acid, and total FAs in cluster I (147.16 μg/mg, 200.31 μg/mg, and 671.24 μg/mg, respectively) were significantly lower than those in cluster II (196.65 μg/mg, 220.16 μg/mg, and 741.78 μg/mg, respectively). Cluster I was perfectly consistent with subsect. Foliolatae, while cluster II was in good agreement with subsect. Dissectifoliae. Therefore, the FA composition of wild herbaceous peony seed oil might be used as a chemotaxonomic marker.

A Randomized Multicenter Phase II Study of Docosahexaenoic Acid in Patients with a History of Breast Cancer, Premalignant Lesions, or Benign Breast Disease

Obesity, a cause of subclinical inflammation, is a risk factor for the development of postmenopausal breast cancer and is associated with poorer cancer outcomes. Docosahexaenoic acid (DHA), an omega-3 fatty acid, possesses anti-inflammatory properties. We hypothesized that treatment with DHA would reduce the expression of proinflammatory genes and aromatase, the rate-limiting enzyme for estrogen biosynthesis, in benign breast tissue of overweight/obese women. A randomized, placebo-controlled, double-blind phase II study of DHA given for 12 weeks to overweight/obese women with a history of stage I-III breast cancer, DCIS/LCIS, Paget's disease, or proliferative benign breast disease was carried out. In this placebo controlled trial, the primary objective was to determine whether DHA (1,000 mg by mouth twice daily) reduced breast tissue levels of TNFα. Secondary objectives included evaluation of the effect of DHA on breast tissue levels of COX-2, IL1β, aromatase, white adipose tissue inflammation, and gene expression by RNA-seq. Red blood cell fatty acid levels were measured to assess compliance. From July 2013 to November 2015, 64 participants were randomized and treated on trial (32 women per arm). Increased levels of omega-3 fatty acids in red blood cells were detected following treatment with DHA (P < 0.001) but not placebo. Treatment with DHA did not alter levels of TNFα (P = 0.71), or other biomarkers including the transcriptome in breast samples. Treatment with DHA was overall well-tolerated. Although compliance was confirmed, we did not observe changes in the levels of prespecified biomarkers in the breast after treatment with DHA when compared with placebo. Cancer Prev Res; 11(4); 203-14. ©2018 AACRSee related editorial by Fabian and Kimler, p. 187.

An age-period-cohort analysis of female breast cancer mortality from 1990-2009 in China

BACKGROUND

Breast cancer is the most common cause of cancer-related death among women. In this paper, we studied the variations in the trends of Chinese female breast cancer mortality by age, period and cohort from 1990 to 2009.

METHODS

The mortality data were collected from the Institute for Health Metrics and Evaluation. An age-period-cohort model and Intrinsic Estimator were used to estimate the age effect, period effect and cohort effect on the Chinese adult female breast cancer mortality risk.

RESULTS

The age effect on Chinese female breast cancer mortality initially increased, but then declined, and showed a reversed "J" shape with age. The period effect of breast cancer mortality continued to rise with the time period and increased by 59% from 1990-1994 to 2005-2009. The cohort effect showed that the mortality risk of Chinese females born after 1911 was on the decline and decreased by 2.2336 from 1911 to 1989. The change rate of the cohort effect on breast cancer mortality fluctuated regularly. Three accelerating decreases and three decelerating decreases were noted in the variation law of the change rate.

CONCLUSION

The results of study show the increasing mortality trend of breast cancer in Chinese female from 1990 to 2009, and the breast cancer mortality risk decreased with birth cohort.

Targeting obesity-related adipose tissue dysfunction to prevent cancer development and progression

The incidence of obesity, a leading modifiable risk factor for common solid tumors, is increasing. Effective interventions are needed to minimize the public health implications of obesity. Although the mechanisms linking increased adiposity to malignancy are incompletely understood, growing evidence points to complex interactions among multiple systemic and tissue-specific pathways including inflamed white adipose tissue. The metabolic and inflammatory consequences of white adipose tissue dysfunction collectively provide a plausible explanation for the link between overweight/obesity and carcinogenesis. Gaining a better understanding of these underlying molecular pathways and developing risk assessment tools that identify at-risk populations will be critical in implementing effective and novel cancer prevention and management strategies.

Enhanced anticancer properties of lomustine in conjunction with docosahexaenoic acid in glioblastoma cell lines

OBJECT

Glioblastoma is a rapidly infiltrating tumor that consistently rematerializes despite various forms of aggressive treatment. Brain tumors are commonly treated with alkylating drugs, such as lomustine, which are chemotherapeutic agents. Use of these drugs, however, is associated with serious side effects. To reduce the side effects, one approach is to combine lower doses of chemotherapeutic drugs with other nontoxic anticancer agents. In this study, using glioblastoma cell lines, the authors investigated the anticancer effects of lomustine, alone and in combination with docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid normally abundant in the brain and known for its anticancer potential.

METHODS

Cells were cultured from 3 human-derived tumor cell lines (U87-MG, DB029, and MHBT161) and supplemented with either DHA or lomustine to determine the growth inhibitory potential using WST-1, a mitochondrial functional indicator. Human-derived cerebral cortex microvascular endothelial cells served as a normal phenotypic control. Cellular incorporation of DHA was analyzed by gas chromatography. Using flow cytometric analysis, the DHA and/or lomustine effect on induction of apoptosis and/or necrosis was quantified; subsequently, the DHA and lomustine effect on cell cycle progression was also assessed. Western blot analysis confirmed the role of downstream cellular targets.

RESULTS

U87-MG growth was inhibited with the supplementation of either DHA (ED50 68.3 μM) or lomustine (ED50 68.1 μM); however, growth inhibition was enhanced when U87-MG cells were administered equimolar doses of each compound, resulting in nearly total growth inhibition at 50 μM. Gas chromatography analysis of the fatty acid profile in DHA-supplemented U87-MG cells resulted in a linear dose-dependent increase in DHA incorporation (< 60 μM). The combination of DHA and lomustine potently induced U87-MG apoptosis and necrosis as indicated by flow cytometric analysis. Activation of caspase-3 and poly (ADP-ribose) polymerase (PARP) was evident in lomustine-treated U87-MG cells, although this activation did not appear to be dependent on DHA supplementation. Additionally, lomustine-treated cells' growth arrested in the G2/M cell cycle stage, regardless of the presence of DHA. Similar to the U87-MG observations, the combination of DHA and lomustine resulted in growth inhibition of 2 additional human-derived glioblastoma cell lines, DB029 and MHBT161. Importantly, in primary human-derived cerebral cortex endothelial cells, this combination was only growth inhibitory (40.8%) at the highest dose screened (100 μM), which indicates a certain degree of selectivity toward glioblastoma.

CONCLUSIONS

Taken together, these data suggest a potential role for a combination therapy of lomustine and DHA for the treatment of glioblastomas.

Oxidized derivative of docosahexaenoic acid preferentially inhibit cell proliferation in triple negative over luminal breast cancer cells

Omega-3 polyunsaturated fatty acids (PUFAs) exert an anticancer effect by affecting multiple cellular mechanisms leading to inhibition of proliferation and induction of apoptosis. It is well known that breast cancer comprises distinct molecular subtypes which differ in their responsiveness to therapeutic and preventive agents. We tested the hypothesis that n-3FA may preferentially affect triple-negative breast cancer cells for which no targeted intervention is presently available. The in vitro antiproliferative effects of n-3 PUFA docosahexaenoic acid (DHA) and its metabolite, 4-OH-DHA as well as its putative metabolite 4-OXO-DHA, were tested in five triple-negative human basal breast cell lines at different stages of transformation (MCF-10F, trMCF, bsMCF, MDA-MB-231, and BT-549) and three luminal breast cancer cell lines (MCF-7, T-47D, and SK-BR-3). Cell proliferation was measured with the tetrazolium MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay. DHA and its oxidized derivatives significantly inhibited cell proliferation (20-90% reduction) of both basal and luminal breast cancer cell lines. The inhibitory effect was more pronounced on triple-negative basal breast cancer cell lines as compared to luminal breast cancer cell lines after 4-OXO-DHA treatment. Our data provide novel information regarding the preferential antitumor effect of oxidized derivatives of DHA on basal type breast cancer.

Analysis of high fat diet induced genes during mammary gland development: identifying role players in poor prognosis of breast cancer

BACKGROUND

Epidemiological studies have shown that consumption of a high-fat diet (HFD) increases the risk of developing breast cancer (BC). Studies in rodents have shown HFD causes changes in the genetic programming of the maturing mammary gland (MG) increasing the susceptibility of developing the disease. Less is known about how HFD induced genes impact BC development. HFD exposure two weeks before conception to six weeks of age was previously shown to dramatically change MG gene expression in 10 week old mice. Therefore, we investigated these differentially expressed HFD-induced genes for their expression in BC using the NKI 295 breast tumor dataset.

RESULTS

To examine the potential role of HFD induced genes in BC, we first investigated whether these HFD-induced genes in mouse MGs were differentially expressed in different types of human BC. Of the 28 HFD induced genes that were differentially expressed between BC subtypes in the NKI set, 79% were significantly higher in basal-like BC. Next, we analyzed whether HFD induced genes were associated with BC prognosis utilizing gene expression and survival data for each HFD induced gene from the NKI data and constructed Kaplan Meier survival plots. Significantly, 93% of the prognosis associated genes (13/14) were associated with poor prognosis (P = 0.002). Kaplan Meier analysis with 249 non-basal-like BC found that all but one of the genes examined were still significantly associated with poor prognosis. Furthermore, gene set enrichment analysis (GSEA) with HFD microarray data revealed that invasive BC genes where enriched in HFD samples that also had lost expression of luminal genes.

CONCLUSIONS

HFD exposed mouse MGs maintain differential expression of genes that are found highly expressed in basal-like breast cancer. These HFD-induced genes associate with poor survival in numerous BC subtypes, making them more likely to directly impact prognosis. Furthermore, HFD exposure leads to a loss in the expression of luminal genes and a gain in expression of mesenchymal and BC invasion genes in MGs. Collectively, our study suggests that HFD exposure during development induces genes associated with poor prognosis, thus identifying how HFD diet may regulate BC development.

Targeting survival pathways in chronic myeloid leukaemia stem cells

Chronic myeloid leukaemia (CML) is a clonal myeloproliferative disorder characterized by the presence of a fusion oncogene BCR-ABL, which encodes a protein with constitutive TK activity. The implementation of tyrosine kinase inhibitors (TKIs) marked a major advance in CML therapy; however, there are problems with current treatment. For example, relapse occurs when these drugs are discontinued in the majority of patients who have achieved a complete molecular response on TKI and these agents are less effective in patients with mutations in the BCR-ABL kinase domain. Importantly, TKI can effectively target proliferating mature cells, but do not eradicate quiescent leukaemic stem cells (LSCs), therefore allowing disease persistence despite treatment. It is essential that alternative strategies are used to target the LSC population. BCR-ABL activation is responsible for the modulation of different signalling pathways, which allows the LSC fraction to evade cell death. Several pathways have been shown to be modulated by BCR-ABL, including PI3K/AKT/mTOR, JAK-STAT and autophagy signalling pathways. Targeting components of these survival pathways, alone or in combination with TKI, therefore represents an attractive potential therapeutic approach for targeting the LSC. However, many pathways are also active in normal stem cells. Therefore, potential targets must be validated to effectively eradicate CML stem cells while sparing normal counterparts. This review summarizes the main pathways modulated in CML stem cells, the recent developments and the use of novel drugs to target components in these pathways which may be used to target the LSC population.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Relations of omega-3 and omega-6 intake with mammographic breast density

PURPOSE

Omega-3 (n-3) and n-6 fatty acids (FA) intake could influence the occurrence of certain diseases such as breast cancer but little is known about their relation to mammographic density (MD). The purpose of this study is to examine the association of the intake of n-3 FA and n-6 FA with MD among 777 premenopausal and 783 postmenopausal women.

METHODS

In this cross-sectional study, FA intake was assessed with a self-administered food-frequency questionnaire and MD was measured using a computer-assisted method. Multivariate analyses were performed by using generalized linear models to evaluate the associations of quartiles of FA intake with MD.

RESULTS

For increasing quartiles of total long-chain n-3 FA intake (< 0.11, 0.11-0.20, 0.21-0.32, and ≥ 0.33 g/day), adjusted mean MD was 29, 29, 27, and 25 %, respectively (P trend = 0.005). This association remained significant among postmenopausal (P trend = 0.006) but not among premenopausal (P trend = 0.21) women. No significant association was found between n-6 FA intake and MD. However, for increasing quartiles of the n-6 FA/long-chain n-3 FA ratio intake (< 31.75, 31.75-52.28, 52.29-94.28, and ≥ 94.29), adjusted mean MD was 26, 27, 29, and 29 %, respectively (P trend = 0.008).

CONCLUSIONS

Higher intake of long-chain n-3 FA was associated with lower MD, suggesting that increased long-chain n-3 FA intake could be a strategy for breast cancer prevention.

Characterization of synergistic anti-cancer effects of docosahexaenoic acid and curcumin on DMBA-induced mammary tumorigenesis in mice

BACKGROUND

The major obstacles to the successful use of individual nutritional compounds as preventive or therapeutic agents are their efficacy and bioavailability. One approach to overcoming this problem is to use combinations of nutrients to induce synergistic effects. The objective of this research was to investigate the synergistic effects of two dietary components: docosahexaenoic acid (DHA), an omega-3 fatty acid present in cold-water fish, and curcumin (CCM), an herbal nutrient present in turmeric, in an in vivo model of DMBA-induced mammary tumorigenesis in mice.

METHODS

We used the carcinogen DMBA to induce breast tumors in SENCAR mice on control, CCM, DHA, or DHA + CCM diets. Appearance and tumor progression were monitored daily. The tumors were harvested 15 days following their first appearance for morphological and immunohistological analysis. Western analysis was performed to determine expression of maspin and survivin in the tumor tissues. Characterization of tumor growth was analyzed using appropriate statistical methods. Otherwise all other results are reported as mean ± SD and analyzed with one-way ANOVA and Tukey's post hoc procedure.

RESULTS

Analysis of gene microarray data indicates that combined treatment with DHA + CCM altered the profile of "PAM50" genes in the SK-BR-3 cell line from an ER⁻/Her-2⁺ to that resembling a "normal-like" phenotype. The in vivo studies demonstrated that DHA + CCM treatment reduced the incidence of breast tumors, delayed tumor initiation, and reduced progression of tumor growth. Dietary treatment had no effect on breast size development, but tumors from mice on a control diet (untreated) were less differentiated than tumors from mice fed CCM or DHA + CCM diets. The synergistic effects also led to increased expression of the pro-apoptotic protein, maspin, but reduced expression of the anti-apoptotic protein, survivin.

CONCLUSIONS

The SK-BR-3 cells and DMBA-induced tumors, both with an ER⁻ and Her-2⁺ phenotype, were affected by the synergistic interaction of DHA and CCM. This suggests that the specific breast cancer phenotype is an important factor for predicting efficacy of these nutraceuticals. The combination of DHA and CCM is potentially a dietary supplemental treatment for some breast cancers, likely dependent upon the molecular phenotype of the cancer.

The janus face of lipids in human breast cancer: how polyunsaturated Fatty acids affect tumor cell hallmarks

For several years, lipids and especially n - 3 and n - 6 polyunsaturated fatty acids (PUFAs) receive much attention in human health. Epidemiological studies tend to correlate a PUFA-rich diet with a reduced incidence of cancer, including breast cancer. However, the molecular and cellular mechanisms supporting the effect of PUFAs in breast cancer cells remain relatively unknown. Here, we review some recent progress in understanding the impact that PUFA may have on breast cancer cell proliferation, apoptosis, migration, and invasion. While most of the results obtained with docosahexaenoic acid and/or eicosapentaenoic acid show a decrease of tumor cell proliferation and/or aggressivity, there is some evidence that other lipids, which accumulate in breast cancer tissues, such as arachidonic acid may have opposite effects. Finally, lipids and especially PUFAs appear as potential adjuvants to conventional cancer therapy.

Serum levels of marine-derived n-3 fatty acids in Icelanders, Japanese, Koreans, and Americans--a descriptive epidemiologic study

In the 1990s Iceland and Japan were known as countries with high fish consumption whereas coronary heart disease (CHD) mortality in Iceland was high and that in Japan was low among developed countries. We described recent data fish consumption and CHD mortality from publicly available data. We also measured CHD risk factors and serum levels of marine-derived n-3 and other fatty acids from population-based samples of 1324 men in Iceland, Japan, South Korea, and the US. CHD mortality in men in Iceland was almost 3 times as high as that in Japan and South Korea. Generally, a profile of CHD risk factors in Icelanders compared to Japanese was more favorable. Serum marine-derived n-3 fatty acids in Iceland were significantly lower than in Japan and South Korea but significantly higher than in the US.

Docosahexaenoic acid: a natural powerful adjuvant that improves efficacy for anticancer treatment with no adverse effects

Epidemiological studies have linked fish oil consumption to a decreased incidence of cancer. The anticancer effects of fish oil are mostly attributed to its content of omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, DHA, because of its unique effect of altering membrane composition, is often regarded as the major omega-3 fatty acid involved in anticancer activity. Although use of DHA as an anticancer drug to prevent or treat human cancer in clinical settings has not yet been well established, recent studies suggest that DHA can be very effective as an adjuvant with other anticancer agents. In this article, we present studies that show the role of DHA in improving anticancer drug efficacy. Several in vitro and animal studies suggest that combining DHA with other anticancer agents often improves efficacy of anticancer drugs and also reduces therapy-associated side effects. Incorporation of DHA in cellular membranes improves drug uptake, whereas increased lipid peroxidation is another mechanism for DHA-mediated enhanced efficacy of anticancer drugs. In addition, several intracellular targets including cyclooxygenase-2, nuclear factor kappa B, peroxisome proliferator-activated receptor gamma, mitogen-activated protein kinase, AKT, and BCL-2/BAX are found to play an important role in DHA-mediated additive or synergistic interaction with anticancer drugs. The data suggest that DHA is a safe, natural compound that can greatly improve the anticancer properties of anticancer drugs. Use of DHA with anticancer treatments provides an avenue to therapeutic improvement that involves less risk or side effects for patients and reduced regulatory burden for implementation.

Omega-3 fatty acids induce apoptosis in human breast cancer cells and mouse mammary tissue through syndecan-1 inhibition of the MEK-Erk pathway

Human epidemiological studies have shown that diets enriched in n-3 polyunsaturated fatty acids (n-3 PUFA) are associated with a lower incidence of cancers including breast cancer. Our previous studies showed that the n-3 PUFA, docosahexaenoic acid (DHA), upregulated syndecan-1 (SDC-1) expression to induce apoptosis in the human breast cancer cell line MCF-7. We now present evidence of a signaling pathway that is impacted by SDC-1 in these cells and in mouse mammary tissues to result in apoptosis. In MCF-7 cells and SK-BR-3 cells, DHA and a SDC-1 ectodomain impaired signaling of the p44/42 mitogen-activated protein kinase (MAPK) pathway by inhibiting the phosphorylation of MAPK/Erk (MEK)/extracellular signal-regulated kinase (Erk) and Bad to induce apoptosis. SDC-1 siRNA significantly enhanced phosphorylation of these signal molecules and blocked the inhibitory effects of DHA on their phosphorylation. SDC-1 siRNA diminished apoptosis of MCF-7 cells, an effect that was markedly blocked by MEK inhibitor, PD98059. In vivo studies used (i) Fat-1 mice, a genetic model able to convert n-6 to n-3 PUFA to result in higher SDC-1 levels in Fat-1 mammary tissue compared with that of wild-type (wt) mice. Phosphorylation of MEK, Erk and Bad was lower in the Fat-1 versus wt tissue and (ii) SDC-1(-/-) mice that demonstrated markedly higher levels of phosphorylated MEK, Erk and Bad in mammary gland tissue compared with those of SDC(+/+) mice. These data elucidate a pathway whereby SDC-1, upregulated by DHA, induces apoptosis in breast cancer cells through inhibition of MEK/Erk/Bad signaling.

Omega-3 Fatty Acids and PPARgamma in Cancer

Omega-3 (or n-3) polyunsaturated fatty acids (PUFAs) and their metabolites are natural ligands for peroxisome proliferator receptor activator (PPAR)gamma and, due to the effects of PPARgamma on cell proliferation, survival, and differentiation, are potential anticancer agents. Dietary intake of omega-3 PUFAs has been associated with a reduced risk of certain cancers in human populations and in animal models. In vitro studies have shown that omega-3 PUFAs inhibit cell proliferation and induce apoptosis in cancer cells through various pathways but one of which involves PPARgamma activation. The differential activation of PPARgamma and PPARgamma-regulated genes by specific dietary fatty acids may be central to their distinct roles in cancer. This review summarizes studies relating PUFAs to PPARgamma and cancer and offers a new paradigm relating an n-3 PUFA through PPARgamma to the expression of the cell surface proteoglycan, syndecan-1, and to the death of cancer cells.

Effect of dietary fat and omega-3 fatty acids on urinary eicosanoids and sex hormone concentrations in postmenopausal women: a randomized controlled feeding trial

Substantial evidence relates increased sex hormone concentrations with increased breast cancer risk. Varying omega-3 (n-3) fatty acid (FA) intake may lead to alterations in eicosanoid balance and changes in circulating sex hormones that reduce risk. To clarify effects of dietary fat and n-3 FA intake on breast cancer risk markers, circulating sex hormones and urinary eicosanoids were measured in response to controlled feeding of diets designed to increase plasma concentrations of n-3 FA. A controlled cross-over feeding trial in postmenopausal women was conducted using 3 diets: high fat (HF; 40% energy from fat), low fat (LF; 20% energy from fat), and low fat plus n-3 FA (LFn3; 20% of energy from fat plus 3% of energy from n-3 FA) in 8-wk feeding periods. Plasma phospholipid fatty acid n-3 increased with the LFn3 relative to HF and LF (P < 0.0001). Plasma estradiol increased by 51% with HF (P = 0.03). Urinary prostaglandin E metabolite increased with HF relative to LF (P = 0.02) and urinary 11-dehydro-thromboxane B(2) increased with HF (P = 0.01). These results do not support a role of n-3 FA in the reduction of sex hormone levels.

Endogenous synthesis of n-3 polyunsaturated fatty acids in Fat-1 mice is associated with increased mammary gland and liver syndecan-1

Long chain n-3 PUFA have been shown to have chemopreventive properties against breast cancer through various mechanisms. One pathway, studied in human breast cancer cell lines, involves upregulation of the proteoglycan, syndecan-1 (SDC-1) by n-3 PUFA-enriched LDL. Using Fat-1 mice that are able to convert n-6 to n-3 PUFA, we tested whether SDC-1 level in vivo is elevated in mammary glands due to endogenously synthesized rather than LDL-derived n-3 PUFA. Female Fat-1 and wild type (wt) mice were fed an n-6 PUFA- enriched diet for 7 weeks. Fatty acid analysis of plasma lipoproteins showed that total n-6 PUFA reflected dietary intake similarly in both genotypes (VLDL, 36.2±2.2 and 40.9±3.9; LDL, 49.0±3.3 and 48.1±2.0; HDL, 54.6±1.2 and 58.2±1.3, mean ± SEM percent of total fatty acids for Fat-1 and wt animals respectively). Lipoprotein percent n-3 PUFA was also similar between groups. However, phospholipids and triglycerides extracted from mammary and liver tissues demonstrated significantly higher n-3 PUFA and a corresponding decrease in the ratio n-6/n-3 PUFA in Fat-1 compared to wt mice. This was accompanied by higher SDC-1 in mammary glands and livers of Fat-1 mice, thus demonstrating that endogenously synthesized n-3 PUFA may upregulate SDC-1 in the presence of high dietary n-6 PUFA.

A synergistic antiproliferation effect of curcumin and docosahexaenoic acid in SK-BR-3 breast cancer cells: unique signaling not explained by the effects of either compound alone

Background

Breast cancer is a collection of diseases in which molecular phenotypes can act as both indicators and mediators of therapeutic strategy. Therefore, candidate therapeutics must be assessed in the context of multiple cell lines with known molecular phenotypes. Docosahexaenoic acid (DHA) and curcumin (CCM) are dietary compounds known to antagonize breast cancer cell proliferation. We report that these compounds in combination exert a variable antiproliferative effect across multiple breast cell lines, which is synergistic in SK-BR-3 cells and triggers cell signaling events not predicted by the activity of either compound alone.

Methods

Dose response curves for CCM and DHA were generated for five breast cell lines. Effects of the DHA+ CCM combination on cell proliferation were evaluated using varying concentrations, at a fixed ratio, of CCM and DHA based on their individual ED₅₀. Detection of synergy was performed using nonlinear regression of a sigmoid dose response model and Combination Index approaches. Cell molecular network responses were investigated through whole genome microarray analysis of transcript level changes. Gene expression results were validated by RT-PCR, and western blot analysis was performed for potential signaling mediators. Cellular curcumin uptake, with and without DHA, was analyzed via flow cytometry and HPLC.

Results

CCM+DHA had an antiproliferative effect in SK-BR-3, MDA-MB-231, MDA-MB-361, MCF7 and MCF10AT cells. The effect was synergistic for SK-BR-3 (ER^- PR^- Her2⁺) relative to the two compounds individually. A whole genome microarray approach was used to investigate changes in gene expression for the synergistic effects of CCM+DHA in SK-BR-3 cells lines. CCM+DHA triggered transcript-level responses, in disease-relevant functional categories, that were largely non-overlapping with changes caused by CCM or DHA individually. Genes involved in cell cycle arrest, apoptosis, inhibition of metastasis, and cell adhesion were upregulated, whereas genes involved in cancer development and progression, metastasis, and cell cycle progression were downregulated. Cellular pools of PPARγ and phospho-p53 were increased by CCM+DHA relative to either compound alone. DHA enhanced cellular uptake of CCM in SK-BR-3 cells without significantly enhancing CCM uptake in other cell lines.

Conclusions

The combination of DHA and CCM is potentially a dietary supplemental treatment for some breast cancers, likely dependent upon molecular phenotype. DHA enhancement of cellular curcumin uptake is one potential mechanism for observed synergy in SK-BR-3 cells; however, transcriptomic data show that the antiproliferation synergy accompanies many signaling events unique to the combined presence of the two compounds.

Role of dietary fatty acids in mammary gland development and breast cancer

Breast cancer is the most common cancer among women worldwide. Estimates suggest up to 35% of cases may be preventable through diet and lifestyle modification. Growing research on the role of fats in human health suggests that early exposure in life to specific fatty acids, when tissues are particularly sensitive to their environment, can have long-term health impacts. The present review examines the role of dietary fat in mammary gland development and breast cancer throughout the lifecycle. Overall, n-3 polyunsaturated fatty acids have promising cancer-preventive effects when introduced early in life, and warrant further research to elucidate the mechanisms of action.

Docosahexaenoic acid induces apoptosis in MCF-7 cells in vitro and in vivo via reactive oxygen species formation and caspase 8 activation

Background

The present study sought to further investigate the in vitro and in vivo anticancer effects of a representative omega-3 fatty acid, docosahexaenoic acid (DHA), with a focus on assessing the induction of oxidative stress and apoptosis as an important mechanism for its anticancer actions.

Methodology/Principal Findings

In vitro studies showed that DHA strongly reduces the viability and DNA synthesis of MCF-7 human breast cancer cells in culture, and also promotes cell death via apoptosis. Mechanistically, accumulation of reactive oxygen species and activation of caspase 8 contribute critically to the induction of apoptotic cell death. Co-presence of antioxidants or selective inhibition or knockdown of caspase 8 each effectively abrogates the cytotoxic effect of DHA. Using athymic nude mice as an in vivo model, we found that feeding animals the 5% fish oil-supplemented diet for 6 weeks significantly reduces the growth of MCF-7 human breast cancer cells in vivo through inhibition of cancer cell proliferation as well as promotion of cell death. Using 3-nitrotyrosine as a parameter, we confirmed that the fish oil-supplemented diet significantly increases oxidative stress in tumor cells in vivo. Analysis of fatty acid content in plasma and tissues showed that feeding animals a 5% fish oil diet increases the levels of DHA and eicosapentaenoic acid in both normal and tumorous mammary tissues by 329% and 300%, respectively.

Conclusions/Significance

DHA can strongly induce apoptosis in human MCF-7 breast cancer cells both in vitro and in vivo. The induction of apoptosis in these cells is selectively mediated via caspase 8 activation. These observations call for further studies to assess the effectiveness of fish oil as a dietary supplement in the prevention and treatment of human breast cancer.

Effect of oil-in-water lipid emulsions prepared with fish oil or soybean oil on the growth of MCF-7 cells and HepG2 cells

The growth of human breast cancer-derived MCF-7 cells was affected by oil-in-water lipid emulsions prepared with fish oil (FO) rich in n-3 fatty acids (FAs) and egg-yolk phosphatides (EYP) (FO-emulsions), but not by lipid emulsions prepared with soybean oil (SO) and EYP (SO-emulsions). On the other hand, the growth of human hepatocarcinoma HepG2 cells was affected by neither SO-emulsions nor FO-emulsions. The growth inhibition of MCF-7 cells in the presence of FO-emulsions was not affected by trolox, but was inhibited by α-lipoic acid, and was even potentiated by ebselen, which works as an antioxidant as well as a lipoxygenase inhibitor. Since prostaglandin E3, generated from n-3 FAs by cyclooxygenases, has a suppressive effect on tumour cell growth, and increases when lipoxygenases are inhibited, these findings suggest that lipid emulsions incorporating triglycerides of n-3 FAs might be effective in suppressing the growth of MCF-7 cells, possibly via oxidative stress and through eicosanoid production with anti-proliferating activity against cancer cells.

A maternal high n-6 fat diet with fish oil supplementation during pregnancy and lactation in rats decreases breast cancer risk in the female offspring

The timing of dietary fat intake may modify breast cancer risk. In addition, n-3 fatty acids reduce, and n-6 fatty acids increase, the risk of breast cancer and a maternal high n-6 fat diet results in a greater risk of breast cancer in the female offspring. We hypothesized that the timing of n-3 fatty acid-enriched fish oil supplementation would be important for reducing the risk of breast cancer. Female rats were fed to a high n-6 fat diet containing 20% of the sunflower oil by weight during pregnancy and lactation, and the female offspring were exposed to fish oil by oral gavage either during the perinatal period via maternal intake or during puberty or adulthood. Exposure during the perinatal period to a maternal high n-6 fat diet with fish oil supplementation significantly reduced the incidence of carcinogen-induced mammary tumors in the female offspring compared to a maternal high n-6 fat diet with no fish oil supplementation or fish oil supplementation later in life (P=.0228 by Cox proportional hazards model). We found that a maternal high n-6 fat diet during pregnancy is more important in increasing the risk of mammary tumors in the female offspring than a maternal high n-6 fat diet during lactation. This study suggests that fish oil supplementation during the perinatal period decreases the effect of a maternal high n-6 fat diet on subsequent carcinogen-induced mammary tumor risk, whereas fish oil supplementation during puberty or adulthood does not.

Fatty fish and fish omega-3 fatty acid intakes decrease the breast cancer risk: a case-control study

Background

Although it is believed that fish ω-3 fatty acids may decrease breast cancer risk, epidemiological evidence has been inconclusive. This study examined the association between fish and fish ω-3 fatty acids intake with the risk of breast cancer in a case-control study of Korean women.

Methods

We recruited 358 incident breast cancer patients and 360 controls with no history of malignant neoplasm from the National Cancer Center Hospital between July 2007 and April 2008. The study participants were given a 103-item food intake frequency questionnaire to determine their dietary consumption of fish (fatty and lean fish) and ω-3 fatty acids derived from fish (eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)).

Results

Using a multivariate logistic regression model, high intake of fatty fish was associated with a reduced risk for breast cancer in both pre- and postmenopausal women (OR [95% CI] for highest vs. lowest intake quartiles, p for trend: 0.19 [0.08 to 0.45], p < 0.001 for premenopausal women, 0.27 [0.11 to 0.66], p = 0.005 for postmenopausal women). Similarly, reductions in breast cancer risk were observed among postmenopausal subjects who consumed more than 0.101 g of EPA (OR [95% CI]: 0.38 [0.15 to 0.96]) and 0.213 g of DHA (OR [95% CI]: 0.32 [0.13 to 0.82]) from fish per day compared to the reference group who consumed less than 0.014 g of EPA and 0.037 g of DHA per day. Among premenopausal women, there was a significant reduction in breast cancer risk for the highest intake quartiles of ω-3 fatty acids (ORs [95% CI]: 0.46 [0.22 to 0.96]), compared to the reference group who consumed the lowest quartile of intake.

Conclusion

These results suggest that high consumption of fatty fish is associated with a reduced risk for breast cancer, and that the intake of ω-3 fatty acids from fish is inversely associated with postmenopausal breast cancer risk.

Gene signaling pathways mediating the opposite effects of prepubertal low-fat and high-fat n-3 polyunsaturated fatty acid diets on mammary cancer risk

In rats, prepubertal exposure to low-fat diet containing n-3 polyunsaturated fatty acids (PUFA) reduces mammary cell proliferation, increases apoptosis, and lowers risk of mammary tumors in adulthood, whereas prepubertal high-fat n-3 PUFA exposure has opposite effects. To identify signaling pathways mediating these effects, we performed gene microarray analyses and determined protein levels of genes related to mammary epithelial cell proliferation. Nursing female rats and rat pups were fed low-fat (16% energy from fat) or high-fat (39% energy from fat) n-3 or n-6 PUFA diets between postnatal days 5 and 24. cDNA gene expression microarrays were used to identify global changes in the mammary glands of 50-day-old rats. Differences in gene expression were confirmed by real-time quantitative PCR, and immunohistochemistry was used to assess changes in the peroxisome proliferator-activated receptor gamma and cyclin D1 levels. DNA damage was determined by 8-hydroxy-2'-deoxyguanosine assay. Expressions of the antioxidant genes thioredoxin, heme oxygenase, NADP-dependent isocitrate dehydrogenase, and metallothionein III, as well as peroxisome proliferator-activated receptor gamma protein, were increased in the mammary glands of 50-day-old rats prepubertally fed the low-fat n-3 PUFA diet. Prepubertal exposure to the high-fat n-3 PUFA diet increased DNA damage and cyclin D1 protein and reduced expression of BRCA1 and cardiotrophin-1. Reduction in mammary tumorigenesis among rats prepubertally fed a low-fat n-3 PUFA diet was associated with an up-regulation of antioxidant genes, whereas the increase in mammary tumorigenesis in the high-fat n-3 PUFA fed rats was linked to up-regulation of genes that induce cell proliferation and down-regulation of genes that repair DNA damage and induce apoptosis.

A comparison of the effects of soya isoflavonoids and fish oil on cell proliferation, apoptosis and the expression of oestrogen receptors alpha and beta in the mammary gland and colon of the rat

Isoflavonoids and fish oil may be protective against colorectal cancer, but the evidence in relation to breast cancer risk is ambiguous. In the present study, we have investigated the impact of soya-derived isoflavonoids and n-3 fatty acids from fish oil, both individually and in combination, on apoptosis, cell proliferation and oestrogen receptor (ER) expression in the colon and mammary gland of the rat. Female rats were fed diets high in n-3 fatty acids (80 g/kg diet) or soya protein (765 mg/kg diet isoflavones) for 2 weeks, and then killed before the removal of the colon and mammary glands. Cell proliferation and apoptosis were quantified morphologically in whole crypts and terminal end buds. The expressions of ERalpha and ERbeta were measured in colon tissue scrapes and the mammary gland. Fish oil significantly increased apoptosis and decreased mitosis in both tissues, an effect associated with a decrease in the expressions of ERalpha and ERbeta. Soya had no effect on apoptosis in either tissue, but reduced mitosis in the colon (P < 0.001) while increasing it in the mammary gland (P = 0.001). The changes in proliferation were associated with contrasting changes in the ER expression such that fish oil significantly decreased both ERbeta and ERalpha, while soya increased ERalpha and decreased ERbeta. The results may provide a novel mechanism by which n-3 fatty acids could reduce cancer risk, but the interpretation of the results in relation to soya consumption and breast cancer risk requires further investigation.

Peroxisome proliferator-activated receptor gamma-mediated up-regulation of syndecan-1 by n-3 fatty acids promotes apoptosis of human breast cancer cells

Diets enriched in n-3 polyunsaturated fatty acids (n-3 PUFA) may protect against breast cancer but biochemical mechanisms are unclear. Our studies showed that the n-3 fatty acid docosahexaenoic acid (DHA) up-regulated syndecan-1 (SDC-1) in human breast cancer cells, and we tested the hypothesis that DHA-mediated up-regulation of SDC-1 induces apoptosis. DHA was delivered to MCF-7 cells by n-3 PUFA-enriched low-density lipoproteins (LDL) or by albumin in the presence or absence of SDC-1 small interfering RNA. The n-3 PUFA induced apoptosis, which was blocked by SDC-1 silencing. We also confirmed that SDC-1 up-regulation and apoptosis promotion by n-3 PUFA was mediated by peroxisome proliferator-activated receptor gamma (PPAR gamma). Using a luciferase gene driven by either a PPAR response element or a DR-1 site present in the SDC-1 promoter, reporter activities were enhanced by n-3 LDL, DHA, and PPAR gamma agonist, whereas activity of a luciferase gene placed downstream of a mutant DR-1 site was unresponsive. Cotransfection with dominant-negative PPAR gamma DNA eliminated the increase in luciferase activity. These data provide strong evidence that SDC-1 is a molecular target of n-3 PUFA in human breast cancer cells through activation of PPAR gamma and that n-3 PUFA-induced apoptosis is mediated by SDC-1. This provides a novel mechanism for the chemopreventive effects of n-3 PUFA in breast cancer.

Dietary fat-gene interactions in cancer

Epidemiologic studies have suggested for decades an association between dietary fat and cancer risk. A large body of work performed in tissue culture and xenograft models of cancer supports an important role of various types of fat in modulating the cancer phenotype. Yet, the molecular mechanisms underlining the effects of fat on cancer initiation and progression are largely unknown. The relationships between saturated fat, polyunsaturated fat, cholesterol or phytanic acid with cancer have been reviewed respectively. However, few have considered the relationship between all of these fats and cancer. The purpose of this review is to present a more cohesive view of dietary fat-gene interactions, and outline a working hypothesis of the intricate connection between fat, genes and cancer.

Inhibitory action of polyunsaturated fatty acids on IMP dehydrogenase

We screened the inhibitor of mouse inosine 5'-monophosphate dehydrogenase (IMPDH) type II from natural compounds, and found that a fatty acid, linoleic acid (C18:2), inhibited IMPDH activity. In the C18:2 fatty acid derivatives, all trans-configuration (i.e., linoelaidic acid), ester form, alcohol form, and addition of the hydroxyl group of linoleic acid had no effect on inhibitory activity. Therefore, both parts of a carboxylic acid and an alkyl chain containing cis-type double bonds of fatty acid might be essential for inhibition. Among the various carbon atom lengths and double bonds of fatty acids examined, the strongest inhibitor was C20:2-fatty acid, eicosadienoic acid, and 50% inhibition was observed at a concentration of 16.1 microM. Eicosadienoic acid induced the inhibition of IMPDH activity and was competitive with respect to IMP (K(i)=3.1 microM). For inhibitory effect, the C20-fatty acids ranked as follows: C20:2>C20:3>C20:1>> C20:4>C20:5, and C20:0 showed no inhibition. The energy-minimized three-dimensional structures of linear-chain C20-fatty acids were calculated, and it was found that a length of 20.7-22.5A and width of 4.7-7.2A in the fatty acid molecular structure was suggested to be important for IMPDH inhibition. Docking simulation of C20-fatty acids and mouse IMPDH type II, which was homology modeled from human IMPDH type II (PDB code: 1NF7), was performed, and the fatty acid could bind to Cys331, which is a amino acid residue of the active site, competitively with IMP. Based on these results, the IMPDH-inhibitory mechanism of fatty acids is discussed.

Dietary omega-3 fatty acids for women

This review details the specific needs of women for omega-3 fatty acids, including alpha linoleic acid (ALA) and the very long chain fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fatty acid (dietary or in capsules) ensures that a woman's adipose tissue contains a reserve of these fatty acids for the developing fetus and the breast-fed newborn infant. This ensures the optimal cerebral and cognitive development of the infant. The presence of large quantities of EPA and DHA in the diet slightly lengthens pregnancy, and improves its quality. Human milk contains both ALA and DHA, unlike that of other mammals. Conditions such as diabetes can alter the fatty acid profile of mother's milk, while certain diets, like those of vegetarians, vegans, or even macrobiotic diets, can have the same effect, if they do not include seafood. ALA, DHA and EPA, are important for preventing ischemic cardiovascular disease in women of all ages. Omega-3 fatty acids can help to prevent the development of certain cancers, particularly those of the breast and colon, and possibly of the uterus and the skin, and are likely to reduce the risk of postpartum depression, manic-depressive psychosis, dementias (Alzheimer's disease and others), hypertension, toxemia, diabetes and, to a certain extend, age-related macular degeneration. Omega-3 fatty acids could play a positive role in the prevention of menstrual syndrome and postmenopausal hot flushes. The normal western diet contains little ALA (less than 50% of the RDA). The only adequate sources are rapeseed oil (canola), walnuts and so-called "omega-3" eggs (similar to wild-type or Cretan eggs). The amounts of EPA and DHA in the diet vary greatly from person to person. The only good sources are fish and seafood, together with "omega-3" eggs.

Current clinical applications of omega-6 and omega-3 fatty acids

BACKGROUND

Recent years have brought a resurgence of research interest in fatty acids, with studied fields running the gamut of human disease. This movement has run in parallel with an increased interest in using nutrition modalities as therapeutic measures, as opposed to their conventional role as energy sources. The aim of this manuscript is to provide a basic review of current clinical applications of omega-6 and omega-3 fatty acids, with a particular focus on the latter.

METHODS

A selective review of the voluminous literature, including randomized controlled trials, meta-analyses, population studies, and case reports, was used to compile data and identify trends in pertinent clinical applications of fatty acid therapy.

CONCLUSIONS

There are a myriad of disorders and maladies that seem to benefit from fatty acid supplementation, specifically omega-3 fatty acids. It has clearly been shown that omega-3 fatty acid supplementation provides a protective benefit in heart disease, and in particular sudden cardiac death. Rheumatoid arthritis (RA) is another disease entity that has been proven to benefit from this nutrition intervention, with improvement in symptoms and diminished nonsteroidal antiinflammatory drug (NSAID) usage. In addition, many psychiatric disorders, particularly schizophrenia and major depressive disorder (MDD), have shown positive results when supplementation has been used as an adjunct to standard pharmacotherapy. The remainder of clinical applications for omega-3 fatty acids requires further investigation. Specifically, according to preliminary clinical evidence, parenteral administration of fatty acids warrants further study.

The role of vitamin D in cancer prevention

Vitamin D status differs by latitude and race, with residents of the northeastern United States and individuals with more skin pigmentation being at increased risk of deficiency. A PubMed database search yielded 63 observational studies of vitamin D status in relation to cancer risk, including 30 of colon, 13 of breast, 26 of prostate, and 7 of ovarian cancer, and several that assessed the association of vitamin D receptor genotype with cancer risk. The majority of studies found a protective relationship between sufficient vitamin D status and lower risk of cancer. The evidence suggests that efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality at low cost, with few or no adverse effects.

Mechanisms mediating the effects of prepubertal (n-3) polyunsaturated fatty acid diet on breast cancer risk in rats

Dietary exposures during childhood may influence later breast cancer risk. We tested in an animal model the hypothesis that prepubertal intake of (n-3) PUFAs, present mainly in fish, reduces susceptibility to breast cancer. Between postnatal days 5 to 25, rat pups were fed (n-3) PUFA-containing diets at a 2:1 ratio of (n-6):(n-3) PUFAs (typical of prehistoric societies) or a control (n-6) PUFA diet at a 17:1 ratio of (n-6):(n-3) PUFAs (comparable with current Western societies). These fatty acids were given in a low- or high-fat context (16 or 39% energy from fat). The low-(n-3) PUFA diet reduced while the high-(n-3) PUFA diet increased carcinogen-induced mammary tumorigenesis. The low-(n-3) PUFA diet reduced mammary cell proliferation and increased apoptosis, particularly in the terminal end buds (the mammary source of malignant breast tumors). The high-(n-3) PUFA diet had opposite effects on these 2 key biomarkers and increased phospho-Akt levels, a survival factor. Microarray analyses identified genes that were permanently upregulated in the low-(n-3) PUFA-exposed glands and function in oxidative damage repair. Serum levels of 8-hydroxy-2'deoxyguanosine, a marker of DNA damage, were significantly reduced in these low-(n-3) PUFA-fed rats, and increased in the high-(n-3) PUFA-exposed group. The latter group exhibited reduced expression of BRCA1, a DNA repair gene. Our results indicate that the opposing susceptibilities to mammary tumorigenesis between the low- versus high-fat (n-3) PUFA-exposed groups were associated with altered DNA damage repair and gene expression linked to proliferation, survival, and differentiation.

Differential effects of delivery of omega-3 fatty acids to human cancer cells by low-density lipoproteins versus albumin

PURPOSE

Omega-3 (n-3) fatty acids (FA) have been proposed to confer tumor-inhibitory properties. In vivo, dietary FA are delivered to tumor cells by two main routes: low-density lipoproteins (LDL) and albumin complexes. High FA concentration in LDL and up-regulation of LDL receptors in tumor cells suggest that the LDL receptor pathway may be the major route for FA delivery. We compared effects of n-3FA delivered to human cancer cells by LDL and albumin.

EXPERIMENTAL DESIGN

LDL was isolated from plasma of African Green monkeys fed diets enriched in fish oil (n-3 FA) or linoleic acid (n-6FA) and used to deliver FA to MCF-7 and PC3 cancer cells. Cell proliferation, apoptosis, and changes in global gene expression were monitored.

RESULTS

Both LDL and albumin were effective in delivering FA to tumor cells and modifying the composition of cell phospholipids. The molar ratio of 20:4 (n-6) to 20:5 (n-3) in phosphatidylcholine and phosphatidylethanolamine was profoundly decreased. Although cell phospholipids were similarly modified by LDL and albumin-delivered FA, effects on cell proliferation and on transcription were markedly different. LDL-delivered n-3 FA were more effective at inhibiting cell proliferation and inducing apoptosis. Expression microarray profiling showed that a significantly higher number of genes were regulated by LDL-delivered than albumin-delivered n-3 FA with little overlap between the two sets of genes.

CONCLUSIONS

These results show the importance of the LDL receptor pathway in activating molecular mechanisms responsible for the tumor inhibitory properties of n-3FA.

Nutritional Intervention With Omega-3 Fatty Acids in a Case of Malignant Fibrous Histiocytoma of the Lungs

We present a case of a 78-yr-old man with malignant fibrous histiocytoma with multiple lesions in both lungs. Following diagnosis, he declined conventional chemotherapy and elected nutritional intervention by increasing intake of omega-3 fatty acids and lowering intake of omega-6 fatty acids. We estimated that he consumed 15 g of the long-chain omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) per day, and the ratio of linoleic acid/long-chain omega-3 fatty acids in his diet was 0.81. Serial computed tomography scans and pulmonary x-rays revealed remarkably a slow and steady decrease in the size and number of bilateral nodules. He has no apparent side effects from consuming large quantities of fish and algae oils rich in DHA and EPA and he remains asymptomatic.

Anticancer properties of propofol-docosahexaenoate and propofol-eicosapentaenoate on breast cancer cells

Introduction

Epidemiological evidence strongly links fish oil, which is rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), with low incidences of several types of cancer. The inhibitory effects of omega-3 polyunsaturated fatty acids on cancer development and progression are supported by studies with cultured cells and animal models. Propofol (2,6-diisopropylphenol) is the most extensively used general anesthetic–sedative agent employed today and is nontoxic to humans at high levels (50 μg/ml). Clinically relevant concentrations of propofol (3 to 8 μg/ml; 20 to 50 μM) have also been reported to have anticancer activities. The present study describes the synthesis, purification, characterization and evaluation of two novel anticancer conjugates, propofol-docosahexaenoate (propofol-DHA) and propofol-eicosapentaenoate (propofol-EPA).

Methods

The conjugates linking an omega-3 fatty acid, either DHA or EPA, with propofol were synthesized and tested for their effects on migration, adhesion and apoptosis on MDA-MB-231 breast cancer cells.

Results

At low concentrations (25 μM), DHA, EPA or propofol alone or in combination had minimal effect on cell adhesion to vitronectin, cell migration against serum and the induction of apoptosis (only 5 to 15% of the cells became apoptotic). In contrast, the propofol-DHA or propofol-EPA conjugates significantly inhibited cell adhesion (15 to 30%) and migration (about 50%) and induced apoptosis (about 40%) in breast cancer cells.

Conclusion

These results suggest that the novel propofol-DHA and propofol-EPA conjugates reported here may be useful for the treatment of breast cancer.

Regulation of HMG-CoA reductase in MCF-7 cells by genistein, EPA, and DHA, alone and in combination with mevastatin

We investigated the regulation of HMG-CoA reductase in MCF-7 human breast cancer cells by genistein, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). All three compounds down-regulated reductase activity, primarily through post-transcriptional effects. In mevastatin-treated cells, only genistein and DHA abrogated the induction of reductase activity caused by this competitive inhibitor. Diets rich in soy isoflavones and fish oils, therefore, may exert anti-cancer effects through the inhibition of mevalonate synthesis in the breast. Genistein and DHA, in particular, may augment the efficacy of statins, increasing the potential for use of these drugs in adjuvant therapy for breast cancer.

Opposing effects of prepubertal low- and high-fat n -3 polyunsaturated fatty acid diets on rat mammary tumorigenesis

To determine whether dietary fat intake during childhood affects the later risk of developing breast cancer, we fed prepubertal rats between post-natal days 5 and 25 a low (16% energy) or high-fat (39% energy) diet composed mainly of n-6 or n-3 polyunsaturated fatty acids (PUFAs) originating either from corn oil or menhaden oil, respectively, in the ratios of 16-17:1 (n-6 PUFA diets) or 2-3:1 (n-3 PUFA diets). We also examined whether changes in risk are associated with perturbations in biological processes previously linked to fatty acid intake and breast cancer. Mammary tumorigenesis was induced by treating 50-day-old rats with the carcinogen 7,12-dimethylbenz[a]anthracene. When compared with the reference low-fat n-6 PUFA diet, prepubertal exposure to the low-fat n-3 PUFA diet decreased, whereas a high-fat n-3 PUFA diet increased mammary tumor incidence; the high-fat n-6 PUFA diet had no effect. Both the low and high-fat n-3 PUFA diets induced mammary epithelial differentiation by reducing the number of terminal end buds (TEBs) and increasing the presence of lobulo-alveolar structures. They also increased lipid peroxidation and reduced cyclooxygenase-2 activity. Prepubertal exposure to the low-fat n-3 PUFA diet increased apoptosis, determined using TUNEL assay, and reduced cell proliferation, determined using PCNA staining. In marked contrast, prepubertal exposure to the high-fat n-3 PUFA diet induced cell proliferation and inhibited apoptosis in the TEBs and lobular structures. The latter is consistent with the finding that pAkt, a survival factor that inhibits apoptosis, was elevated in their mammary glands. In summary, although prepubertal exposure to a low-fat n-3 PUFA diet reduced later mammary tumorigenesis in rats, high levels of this fatty acid can have adverse effects on the prepubertal mammary gland and increase subsequent breast cancer risk.

Omega-3 polyunsaturated fatty acids attenuate breast cancer growth through activation of a neutral sphingomyelinase-mediated pathway

The effect of fish oils and their active omega-3 fatty acid constituents, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), were investigated on breast cancer growth. In in vivo experiments, mice were fed diets that were rich in either omega-3 (fish oil) or omega-6 (corn oil) fatty acids. Three weeks after implantation of MDA-MB-231 breast cancer cells, the tumor volume and weight were significantly lower (p < 0.05) for mice fed the omega-3 diets compared to those fed the omega-6 diets. Dietary fish oil also caused a 40% (p < 0.05) increase in neutral sphingomyelinase (N-SMYase) activity in the tumors. The tumor tissues from fish oil-fed animals expressed elevated p21 (waf1/cip1) mRNA, whereas tumor tissues from corn oil-fed animals exhibited undetectable levels of p21 expression. In in vitro experiments, at concentrations as low as 25 muM, DHA and EPA inhibited the growth of cultured MDA-MB-231 cells in a dose-dependent manner by 20-25% (p < 0.05). N-SMYase activity was also increased by 30-40% (p < 0.05) in the DHA- or EPA-treated cells in which an increase in ceramide formation was observed. DHA and EPA were both observed to enhance membrane bleb formation and also to induce the expression of p21. Omega-3 fatty acids-induced bleb formation and p21 expression were inhibited by the N-SMYase inhibitor GW4869, which also inhibited apoptosis by approximately 40% (p < 0.05). The results suggest that inhibition of breast cancer growth in nude mice by dietary fish oil and inhibition of breast cancer cell growth in culture by treatment with DHA and EPA is mediated by activation of N-SMYase.

Dietary factors modifying breast cancer risk and relation to time of intake

Multiple factors contribute to the development of human breast cancer. However, environmental factors, especially dietary factors, appear to have the greatest effects. Evidence obtained in epidemiological studies has been corroborated by laboratory findings. Dietary components strongly associated with breast cancer include fat and phytochemicals. A diet high in n-3 polyunsaturated fatty acid (PUFA) or monounsaturated fatty acid (MUFA) and low in n-6 PUFA is protective against breast cancer. Some phytochemicals present in fruits and vegetables are also protective. Time of intake appears to be important: lifetime protection may be achieved if one is exposed to a dietary factor that lowers breast cancer risk early in life. Synergistic and antisynergistic interactions between dietary factors can modify breast cancer risk. The available evidence suggests that breast cancer risk can be reduced by early dietary intervention.

Long-chain (n-3) fatty acid intake and risk of cancers of the breast and the prostate: recent epidemiological studies, biological mechanisms, and directions for future research

The association between dietary (n-3) fatty acids and hormone-responsive cancers continues to attract considerable attention in epidemiological, clinical, and experimental studies. We previously reviewed the epidemiological literature on the association between hormone-responsive cancers and the long-chain fatty acids eicosapentaenoic acid and docosahexaenoic acid. We concluded that the compelling evidence from ecological studies, animal models, and mechanistic experiments in vitro was not supported clearly by the available epidemiological data. To various degrees, epidemiological studies published more recently attempted to address some of the methodological limitations plaguing earlier studies by using validated questionnaires, examining specific fatty acids and their interrelationships, and adjusting estimates for a wider range of potentially confounding factors than in previous studies. In this review, our aim was to update the previous review with the results of recent epidemiological studies and to discuss possible biological mechanisms and directions for future research.

Absence of interference of serum IgGs from patients with breast cancer and thyroid autoimmunity on the function of human iodide symporter gene stably transfected in CHO cells

The cause of the association between breast cancer (BC) and thyroid autoimmunity is still unknown. Na+/I- symporter (NIS) is highly expressed in BC cells, and previous studies demonstrated that iodine content in BC is lower than in remote normal breast tissue, suggesting a disorder of iodide uptake in BC. In this study, we evaluated the presence of putative serum autoantibodies able to block the function of NIS in BC patients with thyroid autoimmunity. IgGs were obtained from: a) 11 patients with BC and high antithyroglobulin (TgAb) and antithyroperoxidase (TPOAb) autoantibodies serum concentration; b) 34 patients with Hashimoto's thyroiditis (HT) (1 was euthyroid, 4 had subclinical hypothyroidism and 29 were overtly hypothyroid); c) 15 control subjects. The biological activity of NIS was studied using a chinese hamster ovary (CHO) cell line stably expressing NIS (NIS-CHO). The course of iodide accumulation in NIS-CHO was studied after addition of Na125 I in culture medium. The accumulation of iodide linearly increased between 2 and 10 min, reaching a plateau at 45 min. The preincubation of NIS-CHO with IgGs purified from sera of BC with the highest levels of TPOAb and TgAb caused an inhibition of iodine uptake of no more than 5%. Similar results were obtained using IgGs purified from patients with HT and control subjects. Our data showed no interference of autoantibodies on iodine uptake in patients with BC and thyroid autoimmunity and the very low percentage of inhibition of iodine uptake cannot explain the lower content of iodine in BC tissue.

Translational regulation of gene expression by omega-3 fatty acids

The incidence of some cancers shows dramatic variations around the world that cannot be explained by ethnic or racial differences. Observational studies point to a negative correlation between consumption of fish and incidence of breast and prostate cancer. In vitro and animal model studies indicate that (omega-3) PUFAs present at high concentrations in marine animals inhibit proliferation of cancer cells and growth of tumors. However, how these fatty acids inhibit cell proliferation and tumor growth is a matter of considerable debate. In this review we summarize our recent work indicating that Ca(++) depletion mediated phosphorylation of the alpha subunit of eIF2 and subsequent inhibition of translation initiation account for the anti-cancer activity of (omega-3) PUFAs.