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

Fatty acid traits mediate the effects of uric acid on cancers: a Mendelian randomization study

Introduction

Previous findings on the association between uric acid (UA) levels and cancer risk are conflicting. Moreover, the mechanisms underlying the interactions between UA levels, fatty acid traits, and cancer outcomes remain complex; it is still unclear whether elevated UA levels influence fatty acid traits and, thereby, contribute to an increased cancer risk. Therefore, we aimed to investigate the association between UA levels and cancer risk, with a specific focus on the potential mediating role of fatty acid traits.

Methods

We employed a Mendelian randomization (MR) analysis utilizing genetic data from large-scale genome-wide association studies to assess the causal relationships among UA levels, fatty acid traits, and cancer risk. The primary method used was the inverse variance-weighted approach alongside Bayesian-weighted Mendelian randomization. Other MR models were also applied for comparison. Sensitivity analyses, based on various statistical assumptions, were also performed to evaluate the robustness of the findings. A two-step MR analysis was conducted to explore the mediating effects of fatty acid traits on the relationship between UA levels and cancer risk.

Results and Discussion

Elevated UA levels were associated with an increased risk of in situ neoplasms, cervical cancer, and invasive mucinous ovarian cancer, while they were linked to a decreased risk of cancers of the eye and adnexa, small cell lung cancer, bronchus and lung cancer, respiratory system and intrathoracic organ cancers, as well as lung cancer. Mediation analysis revealed that fatty acid traits, particularly the docosahexaenoic acid/trans fatty acid ratio, mediated the relationship between UA levels and lung cancer risk. These findings underscore the potential of fatty acid traits to mediate the association between UA levels and cancer risk, offering new insights for targeted interventions and potentially improving clinical outcomes.

The association of preoperative serum free fatty acid levels with survival in breast cancer patients

BACKGROUND AND OBJECTIVES

Serum free fatty acids (FFA) are associated with various types of cancer. However, the prognostic value of preoperative serum FFA levels and breast cancer (BC) remains unclear. This study aimed to elucidate the specific relationship between FFA levels and BC outcomes.

METHODS

A retrospective review was conducted on 4133 patients with BC admitted to Sun Yat-sen Memorial Hospital from January 2015 to October 2021. Preoperative serum FFA levels were detected by the enzymatic endpoint method. The relationship between serum FFA levels and clinical characteristics was analyzed based on FFA interquartile range. Restricted cubic splines and multivariate Cox regression analyses were used to assess the relationship between preoperative serum FFA levels and overall survival (OS) in patients with BC. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

According to the FFA interquartile range, FFA levels were significantly correlated with OS (years) (p < 0.001). Restricted cubic spline analysis might reveal a U-shaped relationship between preoperative serum FFA levels and OS, after adjusting for other variables. According to the cutoff points for FFAs, multivariate Cox regression analyses showed that patients with low FFA levels (≤ 250 µmol/L) had higher rates of all-cause mortality and cancer-specific mortality than those with high FFA levels (530-700 µmol/L) in the total population and patients with a BMI of 18.5-24.0 kg/m2. A trend was observed indicating that elevated FFA levels (≥ 715 µmol/L) were associated with worse prognosis; however, this association failed to reach statistical significance.

CONCLUSIONS

There might be a nonlinear U-shaped relationship between preoperative serum FFA levels and survival in breast cancer patients, with lower FFA levels associated with worse OS. The effect of elevated FFA levels on prognosis requires further investigation.

Identification of circulating metabolites linked to the risk of breast cancer: a mendelian randomization study

Objective

This study aimed to investigate potential causal relationships between circulating metabolites and breast cancer risk using Mendelian randomization (MR) analysis.

Materials and Methods

Summary-level genome-wide association study (GWAS) datasets for 249 circulating metabolites were obtained from the UK Biobank. GWAS datasets for estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) breast cancer were acquired from previous studies based on the Combined Oncoarray. Instrumental variables (IVs) were selected from single nucleotide polymorphisms (SNPs) associated with circulating metabolites, and MR analyses were conducted using the inverse-variance weighted (IVW) method as the primary analysis, with additional sensitivity analyses using other MR methods. Odds ratios (OR) and 95% confidence interval (CI) were used to estimate the association of circulating metabolites with breast cancer risk.

Results

The IVW analysis revealed significant causal relationships between 79 circulating metabolites and ER + breast cancer risk, and 10 metabolites were significantly associated with ER-breast cancer risk. Notably, acetate (OR = 1.12, P = 0.03), HDL cholesterol (OR = 1.09, P < 0.001), ration of omega-6 fatty acids to total fatty acids ratio (OR = 1.09, P = 0.01), and phospholipids in large LDL (OR = 1.09, P < 0.001) were linked to an increased risk of ER + breast cancer, while linoleic acid (OR = 0.91, P < 0.001) monounsaturated fatty acids (OR = 0.91, P < 0.001), and total lipids in LDL (OR = 0.91, P < 0.001) were associated with a decreased risk. In ER-breast cancer, glycine, citrate, HDL cholesterol, cholesteryl esters in HDL, cholesterol to total lipids ratio in very large HDL, and cholesterol in large LDL were associated with an increased risk, while the free cholesterol to total lipids in very large HDL was linked to a decreased risk.

Conclusion

This MR approach underscores aberrant lipid metabolism as a key process in breast tumorigenesis, and may inform future prevention and treatment strategies. To further elucidate the underlying mechanisms and explore the potential clinical implications, additional research is warranted to validate the observed associations in this study.

Promising Effects of N-Docosahexaenoyl Ethanolamine in Breast Cancer: Molecular and Cellular Insights

Unhealthy dietary habits have been identified as a risk factor for the development and progression of cancer. Therefore, adopting a healthy eating pattern is currently recommended to prevent the onset of different types of cancers, including breast carcinoma. In particular, the Mediterranean diet, based on high consumption of omega-3 polyunsaturated fatty acids (N-3 PUFAs), such as those found in cold-water fish and other seafood, nuts, and seeds, is recommended to reduce the incidence of several chronic-degenerative diseases. Indeed, the consumption of N-3 PUFAs, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduced the risk of different types of cancer, including breast cancer. Moreover, they can counteract breast cancer progression and reduce the side effects of chemotherapy in breast cancer survival. Studies have demonstrated that DHA, exhibiting greater antitumor activity than EPA in breast cancer, can be attributed to its direct impact on breast cancer cells and also due to its conversion into various metabolites. N-docosahexaenoyl ethanolamine, DHEA, is the most studied DHA derivative for its therapeutic potential in breast cancer. In this review, we emphasize the significance of dietary habits and the consumption of N-3 polyunsaturated fatty acids, particularly DHA, and we describe the current knowledge on the antitumoral action of DHA and its derivative DHEA in the treatment of breast cancer.

Oncogenic signaling of the free-fatty acid receptors FFA1 and FFA4 in human breast carcinoma cells

Globally, breast cancer is the most frequent type of cancer in women, and most breast cancer-associated deaths are due to metastasis and recurrence of the disease. Dietary habits, specifically dietary fat intake is a crucial risk factor involved in breast cancer development and progression. Decades of research has revealed that free-fatty acids (FFA) modulate carcinogenic processes through fatty acid metabolism and lipid peroxidation. The ground-breaking discovery of free-fatty acid receptors, which are members of the G-protein coupled receptor (GPCR) superfamily, has led to the realization that FFA can also act via these receptors to modulate carcinogenic effects. The long-chain free-fatty acid receptors FFA1 (previously termed GPR40) and FFA4 (previously termed GPR120) are activated by mono- and polyunsaturated fatty acids including ω-3, 6, and 9 fatty acids. Initial enthusiasm towards the study of these receptors focused on their insulin secretagogue and sensitization effects, and the downstream associated metabolic regulation. However, recent studies have demonstrated that abnormal expression and/or aberrant FFA1/FFA4 signaling are evident in human breast carcinomas, suggesting that FFA receptors could be a promising target in the treatment of breast cancer. The current review discusses the diverse roles of FFA1 and FFA4 in the regulation of cell proliferation, migration, invasion, and chemotherapy resistance in human breast carcinoma cells and tissue.

Progress in enrichment of n-3 polyunsaturated fatty acid: a review

n-3 Polyunsaturated fatty acids (n-3 PUFA) has been widely used in foods, and pharmaceutical products due to its beneficial effects. The content of n-3 PUFA in natural oils is usually low, which decreases its added value. Thus, there is an increasing demand on the market for n-3 PUFA concentrates. This review firstly introduces the differences in bioavailability and oxidative stability between different types of PUFA concentrate (free fatty acid, ethyl ester and acylglycerol), and then provides a comprehensive discussion of different methods for enrichment of lipids with n-3 PUFA including physical-chemical methods and enzymatic methods. Lipases used for catalyzing esterification, transesterification and hydrolysis reactions play an important role in the production of highly enriched various types of n-3 PUFA concentrates. Lipase-catalyzed alcoholysis or hydrolysis reactions are the mostly employed method to prepare high-quality n-3 PUFA of structural acylglycerols. Although many important advantages offered by lipases in enrichment of n-3 PUFA, the high cost of enzyme limits its industrial-scale production. Further research should focus on looking for biological enzymes with extraordinary catalytic ability and clear selectivity. Other novel technologies such as protein engineering and immobilization may be needed to modify lipases to improve its selectivity, catalytic ability and reuse.

Chemical Composition and Cytotoxic Activity of the Essential Oil and Oleoresins of In Vitro Micropropagated Ansellia africana Lindl: A Vulnerable Medicinal Orchid of Africa

Orchids are rich treasure troves of various important phytomolecules. Among the various medicinal orchids, Ansellia africana stands out prominently in the preparing of various herbal medicines due to its high therapeutic importance. The nodal explants of A. africana were sampled from asymbiotically germinated seedlings on basal Murashige and Skoog (MS) medium and were micropropagated in MS medium supplemented with 3% sucrose and 10 µM meta topolin (mT) + 5 µM naphthalene acetic acid (NAA) +15 µM indole butyric acid (IBA) + 30 µM phloroglucinol (PG). In the present study, the essential oil was extracted by hydrodistillation and the oleoresins by the solvent extraction method from the micropropagated A. africana. The essential oil and the oleoresins were analysed by Gas Chromatography (GC) and GC/MS (Mass spectrometry). A total of 84 compounds were identified. The most predominant components among them were linoleic acid (18.42%), l-ascorbyl 2,6-dipalmitate (11.50%), linolenic acid (10.98%) and p-cresol (9.99%) in the essential oil; and eicosane (26.34%), n-butyl acetate (21.13%), heptadecane (16.48%) and 2-pentanone, 4-hydroxy-4-methyl (11.13%) were detected in the acetone extract; heptadecane (9.40%), heneicosane (9.45%), eicosane (6.40%), n-butyl acetate (14.34%) and styrene (22.20%) were identified and quantified in the ethyl acetate extract. The cytotoxic activity of essential oil and oleoresins of micropropagated A. africana was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromide) assay on Vero cells compared to the standard drug doxorubicin chloride. The present research contains primary information about the therapeutic utility of the essential oil and oleoresins of A. africana with a promising future research potential of qualitative and quantitative improvement through synchronised use of biotechnological techniques.

Single sample scoring of hepatocellular carcinoma: A study based on data mining

Hepatocellular carcinoma (HCC) is a high mortality malignancy and the second leading cause of cancer-related deaths. Because the immune system plays a dual role by assisting the host barrier and tumor progression, there are complex interactions with considerable prognostic significance. Herein, we performed single-sample gene set enrichment (ssGSEA) to explore the tumor microenvironment (TME) and quantify the tumor-infiltrating immune cell (TIIC) subgroups of immune responses based on the HCC cohort of The Cancer Genome Atlas (TCGA) database. We evaluate molecular subpopulations, survival, function, and expression differential associations, as well as reveal potential targets, and biomarkers for immunotherapy. We combined the TME score and the 29 immune cell types in the low, medium, and high immunity groups. The stromal score, immune score, and ESTIMATE score were positively correlated with immune activity but negatively correlated with the tumor purity. There were 23 human leukocyte antigen (HLA)-related genes that were significantly different. However, KIAA1429 was not significant among the different immunity groups. Besides, programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) expression increased with the increase of immune activity. This may provide valuable information for HCC immunotherapy. We also found that there was no significant difference in naïve B cells, macrophages M1, activated mast cells, resting natural killer (NK) cells, and T cells gamma delta among the different immunity groups. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differential proteins were mainly enriched in alpha-linolenic acid (ALA) metabolism, cytokine-cytokine receptor interaction, glycosaminoglycan biosynthesis-heparan sulfate/heparin, glycosphingolipid biosynthesis-ganglio series and proteasome. Our findings provide a deeper understanding of the immune scene, uncovering remarkable immune infiltration patterns of various subtypes of HCC using ssGSEA. This study advances the understanding of immune response and provides a basis for research to enhance immunotherapy.

Enzymatic enrichment of n-3 polyunsaturated fatty acid glycerides by selective hydrolysis

Most natural oils are low in n-3 polyunsaturated fatty acids (n-3 PUFAs) content, which limits their application in health products. In this study, n-3 PUFAs in glyceride form were selectively enriched by lipase-mediated hydrolysis of n-3 PUFA-containing oils. First, commercial lipases were screened, and the lipase AY "Amano" 400SD from Candida cylindracea was the best choice in producing n-3 PUFA glycerides from tuna oil. Subsequently, the hydrolysis conditions were optimized. Under the optimal conditions, the highest n-3 PUFA content in the glyceride fraction was found to be 57.7% after enzymatic hydrolysis. Addition of Ca²⁺ to the system significantly shortened the reaction time from 10 to 4 h. When algal oil was used as substrate, total PUFA contents in the glyceride fraction were 89.9%. This study provides an efficient enzymatic process to produce n-3 PUFA-enriched glyceride concentrates and demonstrates that AY "Amano" 400SD can effectively discriminate against n-3 PUFAs during hydrolysis.

Growth inhibitory and anti-metastatic activity of epithelial cell adhesion molecule targeted three-way junctional delta-5-desaturase siRNA nanoparticle for breast cancer therapy

8-Hydroxyoctanoic acid (8-HOA) produced through cyclooxygenase-2 (COX-2) catalyzed dihomo-γ-linolenic acid (DGLA) peroxidation in delta-5-desaturase inhibitory (D5D siRNA) condition showed an inhibitory effect on breast cancer cell proliferation and migration. However, in vivo use of naked D5D siRNA was limited by off-target silencing and degradation by endonucleases. To overcome the limitation and deliver the D5D siRNA in vivo, we designed an epithelia cell adhesion molecule targeted three-way junctional nanoparticle having D5D siRNA. In this study, we have hypothesized that 3WJ-EpCAM-D5D siRNA will target and inhibit the D5D enzyme in cancer cells leading to peroxidation of supplemented DGLA to 8-HOA resulting in growth inhibitory effect in the orthotopic breast cancer model developed by injecting 4T1 cells. On analysis, we observed a significant reduction in tumor size and metastatic lung nodules in animals treated with a combination of 3WJ-EpCAM-D5D siRNA and DGLA through activating intrinsic apoptotic signaling pathway and by reducing endothelial-mesenchymal damage.

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.

Association of Overweight and Obesity with Breast Cancer During Premenopausal Period in Asia: A Meta-Analysis

Background:

The association of overweight and obesity with breast cancer risk in premenopausal women and in different ethnicities remains in debate, especially among Asian women. The aim of this systematic review and meta-analysis was to determine the association of overweight and obesity with breast cancer during premenopausal period in Asian women.

Methods:

We performed a meta-analysis of research articles on the association of overweight and obesity with breast cancer during premenopausal period in Asian women published from January 2000 to July 2018 in article databases of EBSCO, PubMed, and ProQuest. Pooled odds ratios (ORs) were calculated by fixed and random-effect models. Publication bias was visually evaluated using funnel plots, and then statistically assessed using Egger's and Begg's tests. Review Manager 5.3 (RevMan 5.3) and Stata version 14.2 (Stata Corporation) were used to process the data. We reviewed 886 articles.

Results:

We found 15 studies conducted systematic review continued by meta-analysis of relevant data with 22,362 patients. There was significant association of obesity [OR = 1.36 (95% confidence interval (CI) 1.26–1.47, P < 0.00001)] and overweight [OR = 1.17 (95% CI 1.10–1.25, P < 0.00001)] with breast cancer during premenopausal period in Asian women. In this study, there was no significant publication bias for studies included in overweight and obesity with breast cancer during premenopausal in Asian women.

Conclusions:

This study suggested association of overweight and obesity with breast cancer during premenopausal period in Asian women.

Repurposing mechanistic insight of PDE-5 inhibitor in cancer chemoprevention through mitochondrial-oxidative stress intervention and blockade of DuCLOX signalling

BACKGROUND

This study evaluates the anti-cancer effects of Tadalafil (potent PDE-5 inhibitor) in female albino wistar rats against n-methyl n-nitrosourea induced mammary gland carcinogenesis.

METHODS

The animals were selected and randomly divided among four groups and each group contains six animals per group. The animal tissue and serum samples were evaluated for the presence of antioxidant parameters and the cellular morphology was studied using carminic staining, haematoxylin staining and scanning electron microscopy followed by immunoblotting analysis.

RESULTS

On the grounds of hemodynamic recordings and morphology, n-methyl n-nitrosourea treated group showed distorted changes along with distorted morphological parameters. For morphological analysis, the mammary gland tissues were evaluated using scanning electron microscopy, whole mount carmine staining, haematoxylin and eosin staining. The serum samples were evaluated for the evaluation of oxidative stress markers and inflammatory markers. The level of caspase 3 and 8 were also evaluated for the estimation of apoptosis. The fatty acid profiling of mammary gland tissue was evaluated using fatty acid methyl esters formation. The mitochondrial mediated apoptosis and inflammatory markers were evaluated using immunoblotting assay.

CONCLUSION

The results confirm that Tadalafil treatment restored all the biological markers to the normal and its involvement in mitochondrial mediated death apoptosis pathway along with inhibition of inflammatory markers.

Association of Dietary Intake Ratio of n-3/n-6 Polyunsaturated Fatty Acids with Breast Cancer Risk in Western and Asian Countries: A Meta-Analysis

Objective:

This systematic review and meta-analysis were performed to determine association of dietary intake ratio of n-3/n-6 polyunsaturated fatty acids with breast cancer risk in Western and Asian countries.

Methods:

The authors conducted a meta-analysis of published research articles on association of dietary intake ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) with breast cancer risk in Western and Asian countries published between January 2000 and February 2019 in online article databases of PubMed, ProQuest and EBSCO. Pooled risk ratios (RR) were calculated using fixed and random-effect models. Publication bias was visually evaluated by performing funnel plots and statistically assessed by Egger’s and Begg’s tests. Data were processed by using Stata version 14.2 (Stata Corporation).

Results:

This study reviewed 913 articles. There were 13 studies included in systematic review continued by meta-analysis of relevant data with total number of samples: 275,264 patients. The results showed dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western and Asian countries (RR = 0.99; 95%CI: 0.92-1.07). Dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western countries reached (RR = 0.98; 95%CI: 0.91-1.06) and there was any significant publication bias for studies included. Dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Asian countries reached (RR = 1.18; 95%CI: 0.94-1.47) and there was not any significant publication bias for studies included.

Conclusion:

This analysis confirmed association of dietary intake ratio of n-3/n-6 PUFAs with breast cancer risk in Western and Asian countries. Higher dietary intake ratio is associated with lower risk of breast cancer in Asian countries rather than Western countries. This study suggests increasing dietary intake ratio n-3/n-6 PUFAs will provide benefit for breast cancer prevention.

Maternal exposure to an n-3 polyunsaturated fatty acid diet decreases mammary cancer risk of female offspring in adulthood

Maternal exposure to dietary factors during pregnancy influences the risk of many adult-onset diseases in the later life of offspring. Here, we investigated the effects of maternal n-3 polyunsaturated fatty acid (PUFA) diet on breast cancer risk of female offspring. Pregnant C57BL/6J mice were fed a normal diet (control group), or a high-fat diet rich in safflower oil (SO), fish oil (FO) or flaxseed oil (FSO) (n = 10) throughout gestation and lactation. Their female offspring were fed an AIN-93G diet from weaning. Tumor incidences in offspring induced by 7,12-dimethylbenz[α]anthracene (DMBA) were higher in high-fat groups than in the control group, and were lower in FO and FSO groups than in the SO group. The plasma concentrations of 17β-estradiol (E2), in both pregnant dams and offspring, were significantly lower in FO and FSO groups compared with the SO group. The FO and FSO offspring showed delayed puberty onset, and their mammary glands contained decreased numbers of epithelial terminal end buds (TEBs, targets for malignant transformation) compared with SO offspring. Reduced cell proliferation and increased apoptosis in FO and FSO offspring were observed compared with SO offspring. In line with these changes, maternal exposure to FO promoted the expression of long noncoding RNA (lncRNA) in p53 and apoptosis signaling pathways and inhibited that in NF-κB and Jak-STAT signaling pathways, while FSO promoted the expression of lncRNA in p53 signaling pathways and inhibited that in NF-κB, Jak-STAT and MAPK signaling pathways. In conclusion, maternal exposure to a high-fat diet rich in n-3 PUFAs, both marine- and plant-based, has a protective effect on mammary tumor risk of female offspring in later life.

Effect of Dietary Fish Oil on Mammary Gland Development and Milk Production of Holstein Cow

The aim of this study was to evaluate the effect of feeding oil supplement on mammary gland development and milk production responses in Holstein cows. Ten multiparous Holstein cows (42.2±9.2 d before calving, 3.25±0.25 body condition score, and 620±35 kg body weight) were randomly assigned to treatments. Treatments were a diet with oil added as palm oil (PO; n=5), or fish oil (FO; n=5) given to cows until 63 d in milk. Milk yield was recorded daily, milk composition (fat, protein, lactose, total solid and somatic cell count) was measured weekly and fatty acid profiles of milk fat were determined at first and last week of the experiment. Samples of mammary tissue were obtained at 7 and 63 d in milk by biopsy gun. Tissue slides were analyzed by Image J software. Results showed that fish oil supplemented diet compared to the palm oil supplemented diet increased milk production after 6 weeks of lactation (P<0.05), content of polyunsaturated fatty acids milk fat (P<0.05) and docosahexaenoic acid (P<0.01). Moreover, n-6:n-3 ratio was decreased by fish oil supplement (P<0.05). Histological studies showed that FO increased the relative percentage of tissue area occupied by epithelial cells as well as a number of total alveoli in each microscopic field (P<0.05). Data suggested that feeding fish oil during the dry period and early lactation could improve development and function of the mammary gland in the dairy cow.

Omega-3 Fatty Acids Prevent Early Pancreatic Carcinogenesis via Repression of the AKT Pathway

Pancreatic cancer remains a daunting foe despite a vast number of accumulating molecular analyses regarding the mutation and expression status of a variety of genes. Indeed, most pancreatic cancer cases uniformly present with a mutation in the KRAS allele leading to enhanced RAS activation. Yet our understanding of the many epigenetic/environmental factors contributing to disease incidence and progression is waning. Epidemiologic data suggest that diet may be a key factor in pancreatic cancer development and potentially a means of chemoprevention at earlier stages. While diets high in ω3 fatty acids are typically associated with tumor suppression, diets high in ω6 fatty acids have been linked to increased tumor development. Thus, to better understand the contribution of these polyunsaturated fatty acids to pancreatic carcinogenesis, we modeled early stage disease by targeting mutant KRAS to the exocrine pancreas and administered diets rich in these fatty acids to assess tumor formation and altered cell-signaling pathways. We discovered that, consistent with previous reports, the ω3-enriched diet led to reduced lesion penetrance via repression of proliferation associated with reduced phosphorylated AKT (pAKT), whereas the ω6-enriched diet accelerated tumor formation. These data provide a plausible mechanism underlying previously observed effects of fatty acids and suggest that administration of ω3 fatty acids can reduce the pro-survival, pro-growth functions of pAKT. Indeed, counseling subjects at risk to increase their intake of foods containing higher amounts of ω3 fatty acids could aid in the prevention of pancreatic cancer.

Causal Inference in Cancer Epidemiology: What Is the Role of Mendelian Randomization?

Observational epidemiologic studies are prone to confounding, measurement error, and reverse causation, undermining robust causal inference. Mendelian randomization (MR) uses genetic variants to proxy modifiable exposures to generate more reliable estimates of the causal effects of these exposures on diseases and their outcomes. MR has seen widespread adoption within cardio-metabolic epidemiology, but also holds much promise for identifying possible interventions for cancer prevention and treatment. However, some methodologic challenges in the implementation of MR are particularly pertinent when applying this method to cancer etiology and prognosis, including reverse causation arising from disease latency and selection bias in studies of cancer progression. These issues must be carefully considered to ensure appropriate design, analysis, and interpretation of such studies. In this review, we provide an overview of the key principles and assumptions of MR, focusing on applications of this method to the study of cancer etiology and prognosis. We summarize recent studies in the cancer literature that have adopted a MR framework to highlight strengths of this approach compared with conventional epidemiological studies. Finally, limitations of MR and recent methodologic developments to address them are discussed, along with the translational opportunities they present to inform public health and clinical interventions in cancer. Cancer Epidemiol Biomarkers Prev; 27(9); 995-1010. ©2018 AACR.

Long-Chain Omega-3 Polyunsaturated Fatty Acids Modulate Mammary Gland Composition and Inflammation

Studies in rodents have shown that dietary modifications as mammary glands (MG) develop, regulates susceptibility to mammary tumor initiation. However, the effects of dietary PUFA composition on MGs in adult life, remains poorly understood. This study investigated morphological alterations and inflammatory microenvironments in the MGs of adult mice fed isocaloric and isolipidic liquid diets with varying compositions of omega (ω)-6 and long-chain (Lc)-ω3FA that were pair-fed. Despite similar consumption levels of the diets, mice fed the ω-3 diet had significantly lower body-weight gains, and abdominal-fat and mammary fat pad (MFP) weights. Fatty acid analysis showed significantly higher levels of Lc-ω-3FAs in the MFPs of mice on the ω-3 diet, while in the MFPs from the ω-6 group, Lc-ω-3FAs were undetectable. Our study revealed that MGs from ω-3 group had a significantly lower ductal end-point density, branching density, an absence of ductal sprouts, a thinner ductal stroma, fewer proliferating epithelial cells and a lower transcription levels of estrogen receptor 1 and amphiregulin. An analysis of the MFP and abdominal-fat showed significantly smaller adipocytes in the ω-3 group, which was accompanied by lower transcription levels of leptin, IGF1, and IGF1R. Further, MFPs from the ω-3 group had significantly decreased numbers and sizes of crown-like-structures (CLS), F4/80+ macrophages and decreased expression of proinflammatory mediators including Ptgs2, IL6, CCL2, TNFα, NFκB, and IFNγ. Together, these results support dietary Lc-ω-3FA regulation of MG structure and density and adipose tissue inflammation with the potential for dietary Lc-ω-3FA to decrease the risk of mammary gland tumor formation.

Developmental Origins of Breast Cancer: A Paternal Perspective

The developmental origins of breast cancer have been considered predominantly from a maternal perspective. Although accumulating evidence suggests a paternal programming effect on metabolic diseases, the potential impact of fathers' experiences on their daughters' breast cancer risk has received less attention. In this chapter, we focus on the developmental origins of breast cancer and examine the emerging evidence for a role of fathers' experiences.

Breast cancer is associated to impaired glucose/insulin homeostasis in premenopausal obese/overweight patients

The association between breast cancer (BCa) presence and altered glucose/insulin metabolism is controversial likely due to an inaccurate insulin resistance (IR) assessment and inappropriate stratification of patients by body-mass index (BMI) and menopausal state. 148 women with suspect of sporadic BCa were stratified by BMI and menopause. Fasting levels of glucose, insulin, glycohemoglobin and selected IR-related and tumor-derived markers were measured. Glucose/insulin levels during OGTT were used to calculate insulin resistance/sensitivity indexes. Analysis of 77 BCa-bearing patients and 71 controls showed an association between BCa and IR as demonstrated by impaired glucose/insulin homeostasis (increased fasting- and OGTT-induced glucose levels) and deteriorated IR indexes, which was especially patent in premenopausal women. The association between BCa presence and IR was markedly influenced by BMI, being obese BCa patients significantly more insulin resistant than controls. BCa presence was associated to elevated levels of IR (glucose, triglycerides) and tumor-derived (VEGF) markers, especially in overweight/obese patients. BCa presence is associated to IR in overweight/obese premenopausal but not in premenopausal normal weight or postmenopausal women. Our data support a bidirectional relationship between dysregulated/imbalanced glucose/insulin metabolism and BCa, as tumor- and IR-markers are correlated with the impairment of glucose/insulin metabolism in overweight/obese premenopausal BCa patients.

Alpha-linolenic acid stabilizes HIF-1 α and downregulates FASN to promote mitochondrial apoptosis for mammary gland chemoprevention

Alpha linolenic acid is an essential polyunsaturated fatty acid and is reported to have the anti-cancer potential with no defined hypothesis or mechanism/s. Henceforth present study was in-quested to validate the effect of alpha linolenic acid on mitochondrial apoptosis, hypoxic microenvironment and de novo fatty acid synthesis using in-vitro and in-vivo studies. The IC₅₀ value of alpha linolenic acid was recorded to be 17.55μM against ER+MCF-7 cells. Treatment with alpha linolenic acid was evident for the presence of early and late apoptotic signals along with mitochondrial depolarization, when studied through acridine orange/ethidium bromide and JC-1 staining. Alpha linolenic acid arrested the cell cycle in G2/M phase. Subsequently, the in-vivo efficacy was examined against 7, 12-dimethylbenz anthracene induced carcinogenesis. Treatment with alpha linolenic acid demarcated significant effect upon the cellular proliferation as evidenced through decreased in alveolar bud count, restoration of the histopathological architecture and loss of tumor micro vessels. Alpha linolenic acid restored the metabolic changes to normal when scrutinized through ¹H NMR studies. The immunoblotting and qRT-PCR studies revealed participation of mitochondrial mediated death apoptosis pathway and curtailment of hypoxic microenvironment after treatment with alpha linolenic acid. With all above, it was concluded that alpha linolenic acid mediates mitochondrial apoptosis, curtails hypoxic microenvironment along with inhibition of de novo fatty acid synthesis to impart anticancer effects.

Gestational high-fat diet and bisphenol A exposure heightens mammary cancer risk

In utero exposure to bisphenol A (BPA) increases mammary cancer susceptibility in offspring. High-fat diet is widely believed to be a risk factor of breast cancer. The objective of this study was to determine whether maternal exposure to BPA in addition to high-butterfat (HBF) intake during pregnancy further influences carcinogen-induced mammary cancer risk in offspring, and its dose-response curve. In this study, we found that gestational HBF intake in addition to a low-dose BPA (25 µg/kg BW/day) exposure increased mammary tumor incidence in a 50-day-of-age chemical carcinogen administration model and altered mammary gland morphology in offspring in a non-monotonic manner, while shortening tumor-free survival time compared with the HBF-alone group. In utero HBF and BPA exposure elicited differential effects at the gene level in PND21 mammary glands through DNA methylation, compared with HBF intake in the absence of BPA. Top HBF + BPA-dysregulated genes (ALDH1B1, ASTL, CA7, CPLX4, KCNV2, MAGEE2 and TUBA3E) are associated with poor overall survival in The Cancer Genomic Atlas (TCGA) human breast cancer cohort (n = 1082). Furthermore, the prognostic power of the identified genes was further enhanced in the survival analysis of Caucasian patients with estrogen receptor-positive tumors. In conclusion, concurrent HBF dietary and a low-dose BPA exposure during pregnancy increases mammary tumor incidence in offspring, accompanied by alterations in mammary gland development and gene expression, and possibly through epigenetic reprogramming.

Impact of Diet and Nutrition on Cancer Hallmarks

Diet and nutrition are undeniably two factors that have a major impact on the prevention, progression, and treatment of various cancers. In this review, we will discuss how bioactives from diet and nutritional status affect each of the hallmarks of cancer. We will present recent research and discuss using diet and nutrition as a means to prevent and treat cancer.

Aberrant Phosphorylation of SMAD4 Thr277-Mediated USP9x-SMAD4 Interaction by Free Fatty Acids Promotes Breast Cancer Metastasis

Obesity increases the risk of distant metastatic recurrence and reduces breast cancer survival. However, the mechanisms behind this pathology and identification of relevant therapeutic targets are poorly defined. Plasma free fatty acids (FFA) levels are elevated in obese individuals. Here we report that TGFβ transiently activates ERK and subsequently phosphorylates SMAD4 at Thr277, which facilitates a SMAD4-USP9x interaction, SMAD4 nuclear retention, and stimulates TGFβ/SMAD3-mediated transcription of Twist and Snail. USP9x inhibited the E3 ubiquitin-protein ligase TIF1γ from binding and monoubiquitinating SMAD4, hence maintaining the SMAD4 nuclear retention. FFA further facilitated TGFβ-induced ERK activation, SMAD4 phosphorylation, and nuclear retention, promoting TGFβ-dependent cancer progression. Inhibition of ERK and USP9x suppressed obesity-induced metastasis. In addition, clinical data indicated that phospho-ERK and -SMAD4 levels correlate with activated TGFβ signaling and metastasis in overweight/obese patient breast cancer specimens. Altogether, we demonstrate the vital interaction of USP9x and SMAD4 for governing TGFβ signaling and dyslipidemia-induced aberrant TGFβ activation during breast cancer metastasis. Cancer Res; 77(6); 1383-94. ©2017 AACR.

Raman Spectroscopic Analysis Reveals Abnormal Fatty Acid Composition in Tumor Micro- and Macroenvironments in Human Breast and Rat Mammary Cancer

Fatty acids play essential roles in the growth and metastasis of cancer cells. To facilitate their avid growth and proliferation, cancer cells not only alter the fatty acid synthesis and metabolism intracellularly and extracellularly, but also in the macroenvironment via direct or indirect pathways. We report here, using Raman micro-spectroscopy, that an increase in the production of polyunsaturated fatty acids (PUFAs) was identified in both cancerous and normal appearing breast tissue obtained from breast cancer patients and tumor-bearing rats. By minimizing confounding effects from mixed chemicals and optimizing the signal-to-noise ratio of Raman spectra, we observed a large-scale transition from monounsaturated fatty acids to PUFAs in the tumor while only a small subset of fatty acids transitioned to PUFAs in the tumor micro- and macroenvironment. These data have important implications for further clarifying the macroenvironmental effect of cancer progression and provide new potential approaches for characterizing the tumor micro- and macroenvironment of breast cancer in both pre-clinical animal studies and clinical applications.

Different Biological Action of Oleic Acid in ALDHhigh and ALDHlow Subpopulations Separated from Ductal Carcinoma In Situ of Breast Cancer

The mechanisms underlying breast cancer progression of ductal carcinoma in situ (DCIS) associated with fatty acids are largely unknown. In the present study, we compared the action of oleic acid (OA) on two human DCIS cell lines, MCF10DCIS.COM (ER/PR/HER2-negative) and SUM225 (HER2 overexpressed). OA led to a significant increase in proliferation, migration, lipid accumulation and the expression of lipogenic proteins, such as SREBP-1, FAS and ACC-1, in MCF10DCIS.COM cells but not SUM225 cells. The ALDH^high subpopulation analyzed by the ALDEFLUOR assay was approximately 39.2±5.3% of MCF10DCIS.COM cells but was small (3.11±0.9%) in SUM225 cells. We further investigated the different biological action of OA in the distinct ALDH^low and ALDH^high subpopulations of MCF10DCIS.COM cells. OA led to an increase in the expression of ALDH1A1, ALDH1A2 and ALDH1A3 in MCF10DCIS.COM cells. SREBP-1 and ACC-1 were highly expressed in ALDH^high cells relative to ALDH^low cells, whereas FAS was higher in ALDH^low cells. In the presence of OA, ALDH^high cells were more likely to proliferate and migrate and displayed significantly high levels of SREBP-1 and FAS and strong phosphorylation of FAK and AKT relative to ALDH^low cells. This study suggests that OA could be a critical risk factor to promote the proliferation and migration of ALDH^high cells in DCIS, leading to breast cancer progression.

Dietary patterns and the risk of female breast cancer among participants of the Canadian National Enhanced Cancer Surveillance System

OBJECTIVES

The role of diet in the etiology of breast cancer is not well understood despite extensive research. In the majority of this work, a single nutrient-based approach has been used which does not take into account combinations of food that are consumed. An alternative to the single nutrient approach is to identify patterns in the dietary intake information and relate these patterns to disease incidence. This investigation characterized dietary patterns among participants of a Canadian case-control study and related these dietary patterns to the incidence of breast cancer.

METHODS

Dietary and other risk factor data from cases and controls of the Canadian National Enhanced Cancer Surveillance System were collected using self-administered questionnaires. Principal component factor analysis was used to classify individuals based on their dietary patterns. The relationship between these dietary patterns and breast cancer was evaluated using logistic regression. The derived odds ratios and their 95% confidence limits were adjusted for several factors, such as smoking, alcohol intake, environmental tobacco smoke exposure and obesity.

RESULTS

In the 2,009 cases and 2,086 controls, three dietary patterns were identified: western, healthy and vitamin. The highest quartile of the "healthy" dietary pattern was related to a 22% decrease in breast cancer risk (95% CI: 0.61-1.00), relative to the lowest quartile. The fourth quartile of the "vitamin" dietary pattern was associated with a 14% decrease in breast cancer risk (95% CI: 0.70-1.04) relative to the first. No statistically significant associations between the "western" dietary pattern and breast cancer were found. These associations were neither confounded nor modified by menopausal status.

CONCLUSION

Our analyses reveal that individual dietary items tend to cluster together in such a way that there are three distinct dietary patterns in this sample of Canadian women. Some of these patterns, in turn, were associated with the risk of breast cancer.

Dietary Fat Intake During Adolescence and Breast Density Among Young Women

BACKGROUND

Lack of association between fat intake and breast cancer risk in cohort studies might be attributed to the disregard of temporal effects during adolescence when breasts develop and are particularly sensitive to stimuli. We prospectively examined associations between adolescent fat intakes and breast density.

METHOD

Among 177 women who participated in the Dietary Intervention Study in Children, dietary intakes at ages 10-18 years were assessed on five occasions by 24-hour recalls and averaged. We calculated geometric mean and 95% confidence intervals for MRI-measured breast density at ages 25-29 years across quartiles of fat intake using linear mixed-effect regression.

RESULTS

Comparing women in the extreme quartiles of adolescent fat intakes, percent dense breast volume (%DBV) was positively associated with saturated fat (mean = 16.4% vs. 21.5%; Ptrend < 0.001). Conversely, %DBV was inversely associated with monounsaturated fat (25.0% vs. 15.8%; Ptrend < 0.001) and the ratio of polyunsaturated fat to saturated fat (P/S ratio; 19.1% vs. 14.3%; Ptrend < 0.001). When examining intake by pubertal stages, %DBV was inversely associated with intake of polyunsaturated fat (20.8% vs. 16.4%; Ptrend = 0.04), long-chain omega-3 fat (17.8% vs. 15.8%; Ptrend < 0.001), and P/S ratio (22.5% vs. 16.1%; Ptrend < 0.001) before menarche, but not after. These associations observed with %DBV were consistently observed with absolute dense breast volume but not with absolute nondense breast volume.

CONCLUSIONS

In our study, adolescent intakes of higher saturated fat and lower mono- and polyunsaturated fat are associated with higher breast density measured approximately 15 years later.

IMPACT

The fat subtype composition in adolescent diet may be important in early breast cancer prevention. Cancer Epidemiol Biomarkers Prev; 25(6); 918-26. ©2016 AACR.

An efficient and robust fatty acid profiling method for plasma metabolomic studies by gas chromatography-mass spectrometry

BACKGROUND

Targeted metabolomic analysis of fatty acids has linked the dysregulation of fatty acids to many diseases. This study selected five frequently used fatty acid derivatization methods for comparison.

METHODS

We compared the method precisions and derivatization efficiencies, the most economical and best performing method was subjected to method validation. Twenty-four fatty acid standards were used to validate the method, which was later applied to the investigation of potential fatty acid markers of breast cancer.

RESULTS

The acetyl chloride method was demonstrated to provide the best derivatization efficiency and lowest cost for plasma samples. The ionic liquid column successfully separated positional and geometric fatty acid isomers within 26 min under the optimized conditions. Intra-day and inter-day CVs for most of the fatty acids were <10%. Over 90% of the results showed recoveries within 85%-115%. The validated method was applied to investigate potential fatty acid markers of breast cancer. The fatty acid profiling results revealed that 3 fatty acids (C22:0, C24:0, C18:2n6) were significantly lower in both pre- and post-menopausal breast cancer patients (P<0.05).

CONCLUSIONS

We demonstrated that the proposed method is an accurate, efficient and economical method for plasma metabolomic studies of fatty acids.

n-3 Polyunsaturated Fatty Acids and their Role in Cancer Chemoprevention

Polyunsaturated fatty acids (PUFAs), including omega-3 (n-3) and omega-6 (n-6) PUFAs, are essential for human health. Recent research shows n-3 PUFAs and their mediators can inhibit inflammation, angiogenesis and cancer via multiple mechanisms, including reduced release of n-6 fatty acid arachidonic acid from cell membranes, inhibition of enzymatic activities, and direct competition with arachidonic acid for enzymatic conversions. In this review, we discuss inflammation-related cancer, anti-inflammatory effects of n-3 PUFA lipid mediators, antineoplastic activities of n-3 PUFA in vitro and in vivo, and present an update on recent human trials.

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.

Development and application of a comparative fatty acid analysis method to investigate voriconazole-induced hepatotoxicity

BACKGROUND

As fatty acids play an important role in biological regulation, the profiling of fatty acid expression has been used to discover various disease markers and to understand disease mechanisms. This study developed an effective and accurate comparative fatty acid analysis method using differential labeling to speed up the metabolic profiling of fatty acids.

METHODS

Fatty acids were derivatized with unlabeled (D0) or deuterated (D3) methanol, followed by GC-MS analysis. The comparative fatty acid analysis method was validated using a series of samples with different ratios of D0/D3-labeled fatty acid standards and with mouse liver extracts.

RESULTS

Using a lipopolysaccharide (LPS)-treated mouse model, we found that the fatty acid profiles after LPS treatment were similar between the conventional single-sample analysis approach and the proposed comparative approach, with a Pearson's correlation coefficient of approximately 0.96. We applied the comparative method to investigate voriconazole-induced hepatotoxicity and revealed the toxicity mechanism as well as the potential of using fatty acids as toxicity markers.

CONCLUSIONS

In conclusion, the comparative fatty acid profiling technique was determined to be fast and accurate and allowed the discovery of potential fatty acid biomarkers in a more economical and efficient manner.

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.

Fatty acid and phospholipid biosynthetic pathways are regulated throughout mammary epithelial cell differentiation and correlate to breast cancer survival

This work combined gene and protein expression, gas chromatography-flame ionization detector, and hydrophilic interaction liquid chromatography-tandem mass spectrometry to compare lipid metabolism changes in undifferentiated/proliferating vs. functionally differentiated mammary epithelial cells (MECs) and to study their correlation to breast cancer survival. Sixty-eight genes involved in lipid metabolism were changed in MEC differentiation. Differentiated cells showed induction of Elovl6 (2-fold), Scd1 (4-fold), and Fads2 (2-fold), which correlated with increased levels of C16:1 n-7 and C18:1 n-9 (1.5-fold), C20:3 n-6 (2.5-fold), and C20:4 n-6 (6-fold) fatty acids (FAs) and more phospholipids (PLs) containing these species. Further, increased expression (2- to 3-fold) of genes in phosphatidylethanolamine (PE) de novo biosynthesis resulted in a 20% PE increase. Proliferating/undifferentiated cells showed higher C16:0 (1.7-fold) and C18:2 n-6 (4.2-fold) levels and more PLs containing C16:0 FAs [PC(16:0/16:1), PG(16:0/18:2), PG(16:0/18:1), and SM(16:0/18:0)]. Kaplan-Meier analysis of data from 3455 patients with breast cancer disclosed a positive correlation for 59% of genes expressed in differentiated MECs with better survival. PE biosynthesis and FA oxidation correlated with better prognosis in patients with breast cancer, including the basal-like subtype. Therefore, genes involved in mammary gland FA and PL metabolism and their resulting molecular species reflect the cellular proliferative ability and differentiation state and deserve further studies as potential markers of breast cancer progression

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

Background

Breast cancer is attributable to modifiable risk factors including the intake of dietary n-3 polyunsaturated fatty acids (PUFA). A key piece of evidence, yet to be addressed, that would demonstrate a causal relationship between n-3 PUFA and breast cancer, is a dose-dependent effect of n-3 PUFA on tumour outcomes. Thus, the objective of the present study was to determine whether n-3 PUFA reduces mammary gland tumor outcomes in a dose-dependent manner in female MMTV-neu(ndl)-YD5 transgenic mice, an aggressive model of human breast cancer.

Methods

Harems were provided one of three experimental diets comprised of 0, 3 or 9% (w/w) menhaden fish oil containing n-3 PUFA. Female offspring were weaned onto the same parental diet and maintained on their respective diet for 20 weeks. Tumour onset, size and multiplicity were measured throughout the study. Fatty acid composition of mammary gland and tumours were determined by gas–liquid chromatography.

Results

Tumour size was significantly (p < 0.05) reduced in a dose-dependent manner. n-3 PUFA were also incorporated in a dose-dependent manner; differential incorporation was observed for eicosapentaenoic and docosapentaenoic acids into mammary gland tissue, while docosahexaenoic acid was preferentially incorporated into tumours.

Conclusion

Overall, the present study provides fundamental knowledge about the dose-dependent effect of n-3 PUFA on tumour outcomes in a pre-clinical model and also sheds light on the differential role of individual n-3 PUFA on tumour outcomes.

Maternal metabolic perturbations elicited by high-fat diet promote Wnt-1-induced mammary tumor risk in adult female offspring via long-term effects on mammary and systemic phenotypes

Many adult chronic diseases are thought to be influenced during early life by maternal nutrition; however, the underlying mechanisms remain largely unknown. Obesity-related diseases may be due partly to high fat consumption. Herein, we evaluated mammary tumor risk in female mouse mammary tumor virus-Wnt-1 transgenic (Tg) offspring exposed to high-fat diet (HFD) or control diet (CD) (45% and 17% kcal from fat, respectively) during gestation and lactation, with CD provided to progeny at weaning. In Tg offspring, maternal HFD exposure increased mammary tumor incidence and decreased tumor latency without affecting tumor volume. Tumor risk was associated with higher tumor necrosis factor-α and insulin and altered oxidative stress biomarkers in sera and with early changes in mammary expression of genes linked to tumor promotion [interleukin 6 (Il6)] or inhibition [phosphatase and tensin homolog deleted on chromosome 10 (Pten), B-cell lymphoma 2 (Bcl2)]. Corresponding wild-type progeny exposed to maternal HFD displayed accelerated mammary development, higher mammary adiposity, increased insulin resistance and early changes in Pten, Bcl2 and Il6, than CD-exposed offspring. Dams-fed HFD showed higher serum glucose and oxidative stress biomarkers but comparable adiposity compared with CD-fed counterparts. In human breast cancer MCF-7 cells, sera from maternal HFD-exposed Tg offspring elicited changes in PTEN, BCL2 and IL6 gene expression, mimicking in vivo exposure; increased cell viability and mammosphere formation and induced measures [insulin receptor substrate-1 (IRS-1), IRS-2] of insulin sensitivity. Serum effects on IRS-1 were recapitulated by exogenous insulin and the PTEN-specific inhibitor SF1670. Hyperinsulinemia and PTEN loss-of-function may thus, couple maternal HFD exposure to enhanced insulin sensitivity via increased mammary IRS-1 expression in progeny, to promote breast cancer risk.

Lifelong exposure to n-3 PUFA affects pubertal mammary gland development

There is growing evidence that early developmental periods may importantly influence future breast cancer risk. Also, there is great interest in the role of dietary fat in breast cancer risk, but the role of dietary fat during pubertal mammary gland development remains poorly understood. This study investigated the effect of n-3 polyunsaturated fatty acids (PUFA) using complementary dietary and genetic approaches to examine the effect of lifelong exposure of n-3 PUFA or n-6 PUFA (control) on mammary gland development and fatty acid composition. n-3 PUFA from both diet and genetics were enriched in mammary glands as early as 3 weeks of age. Parameters related to mammary gland development, including number of terminal end buds (TEB), percent coverage of ductal tree, and infiltration of TEB, were influenced by n-3 PUFA at 3 and 4 weeks of age. Overall, findings suggest that n-3 PUFA incorporation into the mammary gland early in life plays a role in the morphological development of the mammary gland during puberty.

Exposure to lard-based high-fat diet during fetal and lactation periods modifies breast cancer susceptibility in adulthood in rats

The present study investigated whether early life exposure to high levels of animal fat increases breast cancer risk in adulthood in rats. Dams consumed a lard-based high-fat (HF) diet (60% fat-derived energy) or an AIN93G control diet (16% fat-derived energy) during gestation or gestation and lactation. Their 7-week-old female offspring were exposed to 7,12-dimethyl-benzo[a]anthracene to induce mammary tumors. Pregnant dams consuming an HF diet had higher circulating leptin levels than pregnant control dams. However, compared to the control offspring, significantly lower susceptibility to mammary cancer development was observed in the offspring of dams fed an HF diet during pregnancy (lower tumor incidence, multiplicity and weight), or pregnancy and lactation (lower tumor multiplicity only). Mammary epithelial elongation, cell proliferation (Ki67) and expression of NFκB p65 were significantly lower and p21 expression and global H3K9me3 levels were higher in the mammary glands of rats exposed to an HF lard diet in utero. They also tended to have lower Rank/Rankl ratios (P=.09) and serum progesterone levels (P=.07) than control offspring. In the mammary glands of offspring of dams consuming an HF diet during both pregnancy and lactation, the number of terminal end buds, epithelial elongation and the BCL-2/BAX ratio were significantly lower and serum leptin levels were higher than in the controls. Our data confirm that the breast cancer risk of offspring can be programmed by maternal dietary intake. However, contrary to our expectation, exposure to high levels of lard during early life decreased later susceptibility to breast cancer.

Ratio of n-3/n-6 PUFAs and risk of breast cancer: a meta-analysis of 274135 adult females from 11 independent prospective studies

Background

Increased ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) in diet or serum may have a protective effect on the risk of breast cancer (BC); however, the conclusions from prospective studies are still controversial. The purpose of this study is to ascertain the relationship between intake ratio of n-3/n-6 PUFAs and the risk of BC, and estimate the potential summarized dose–response trend.

Methods

Relevant English-language studies were identified through Cochrane Library, PubMed and EMBASE database till April 2013. Eligible prospective studies reporting the multivariate adjusted risk ratios (RRs) for association of n-3/n-6 PUFAs ratio in diet or serum with BC risk. Data extraction was conducted independently by 2 investigators; disagreements were reconciled by consensus. Study quality was assessed using the Newcastle-Ottawa scale. Study-specific RRs were combined via a random-effects model.

Results

Six prospective nested case–control and 5 cohort studies, involving 8,331 BC events from 274,135 adult females across different countries, were included in present study. Subjects with higher dietary intake ratio of n-3/n-6 PUFAs have a significantly lower risk of BC among study populations (pooled RR = 0.90; 95% CI: 0.82, 0.99), and per 1/10 increment of ratio in diet was associated with a 6% reduction of BC risk (pooled RR = 0.94; 95% CI: 0.90, 0.99; P for linear trend = 0.012). USA subjects with higher ratio of n-3/n-6 in serum phospholipids (PL) have a significantly lower risk of BC (pooled RR = 0.62; 95% CI: 0.39, 0.97; I² = 0.00%; P for metaregression = 0.103; P for a permutation test = 0.100), and per 1/10 increment of ratio in serum PL was associated with 27% reduction of BC risk (pooled RR = 0.73; 95% CI: 0.59, 0.91; P for linear trend = 0.004; P for metaregression = 0.082; P for a permutation test = 0.116).

Conclusions

Higher intake ratio of n-3/n-6 PUFAs is associated with lower risk of BC among females, which implies an important evidence for BC prevention and treatment is by increasing dietary intake ratio of n-3/n-6 PUFA. No firm conclusions from USA populations could be obtained, due to the limited numbers of USA studies.

Maternal dietary fat affects the LT muscle fatty acid composition of progeny at weaning and finishing stages in pigs

The present study was conducted to investigate whether maternal dietary fat affects the fatty acid composition of the longissimus thoracis (LT) muscle in offspring pigs at weaning and finishing stages. Fourteen sows were randomly assigned to a control or a high fat (HF) group. The HF sows received a diet containing 8% corn oil starting seven days before farrowing until weaning. The results showed that a high-fat diet significantly increased the contents of serum-lipid-related indexes in the sows. Although the triglyceride content did not change, the C18:2n-6 content was higher in the colostrum and in the LT muscle of offspring pigs at both investigated stages. The total n-6 content and the n-6/n-3 ratio generally increased. This study demonstrated that maternal dietary fat during lactation affects the fatty acid composition of the LT muscle of progeny at weaning, and can have persistent effects in later life.

Lasting effects on body weight and mammary gland gene expression in female mice upon early life exposure to n-3 but not n-6 high-fat diets

Exposure to an imbalance of nutrients prior to conception and during critical developmental periods can have lasting consequences on physiological processes resulting in chronic diseases later in life. Developmental programming has been shown to involve structural and functional changes in important tissues. The aim of the present study was to investigate whether early life diet has a programming effect on the mammary gland. Wild-type mice were exposed from 2 weeks prior to conception to 6 weeks of age to a regular low-fat diet, or to high-fat diets based on either corn oil or flaxseed oil. At 6 weeks of age, all mice were shifted to the regular low-fat diet until termination at 10 weeks of age. Early life exposure to a high-fat diet, either high in n-6 (corn oil) or in n-3 (flaxseed oil) polyunsaturated fatty acids, did not affect birth weight, but resulted in an increased body weight at 10 weeks of age. Transcriptome analyses of the fourth abdominal mammary gland revealed differentially expressed genes between the different treatment groups. Exposure to high-fat diet based on flaxseed oil, but not on corn oil, resulted in regulation of pathways involved in energy metabolism, immune response and inflammation. Our findings suggest that diet during early life indeed has a lasting effect on the mammary gland and significantly influences postnatal body weight gain, metabolic status, and signaling networks in the mammary gland of female offspring.

Redefining the impact of nutrition on breast cancer incidence: is epigenetics involved?

Breast cancer incidence is rising worldwide with an increase in aggressive neoplasias in young women. Possible factors involved include lifestyle changes, notably diet that is known to make an impact on gene transcription. However, among dietary factors, there is sufficient support for only greater body weight and alcohol consumption whereas numerous studies revealing an impact of specific diets and nutrients on breast cancer risk show conflicting results. Also, little information is available from middle- and low-income countries. The diversity of gene expression profiles found in breast cancers indicates that transcription control is critical for the outcome of the disease. This suggests the need for studies on nutrients that affect epigenetic mechanisms of transcription, such as DNA methylation and post-translational modifications of histones. In the present review, a new examination of the relationship between diet and breast cancer based on transcription control is proposed in light of epidemiological, animal and clinical studies. The mechanisms underlying the impact of diets on breast cancer development and factors that impede reaching clear conclusions are discussed. Understanding the interaction between nutrition and epigenetics (gene expression control via chromatin structure) is critical in light of the influence of diet during early stages of mammary gland development on breast cancer risk, suggesting a persistent effect on gene expression as shown by the influence of certain nutrients on DNA methylation. Successful development of breast cancer prevention strategies will require appropriate models, identification of biological markers for rapid assessment of preventive interventions, and coordinated worldwide research to discern the effects of diet.

Mammary tumor development is directly inhibited by lifelong n-3 polyunsaturated fatty acids

INTRODUCTION

Despite the advocacy that diet may be a significant contributor to cancer prevention, there is a lack of direct evidence from epidemiological and experimental studies to substantiate such claims. Experimental studies suggest that n-3 polyunsaturated fatty acids (n-3 PUFA) from marine oils may reduce breast cancer risk, however, findings are equivocal. Thus, in this study, novel transgenic mouse models were employed to provide, for the first time, direct evidence for an anti-cancer role of n-3 PUFA in mammary tumorigenesis.

METHODS

fat-1 Mice, which are capable of endogenous n-3 PUFA synthesis, were bred with mouse mammary tumor virus (MMTV)-neu(ndl)-YD5 mice, an aggressive breast cancer model. The resultant offspring, including novel hybrid progeny, were assessed for tumor onset, size and multiplicity as well as n-3 PUFA composition in mammary gland and tumor tissue. A complementary group of MMTV-neu(ndl)-YD5 mice were fed n-3 PUFA in the diet.

RESULTS

Mice expressing MMTV-neu(ndl)-YD5 and fat-1 displayed significant (P<.05) reductions in tumor volume (~30%) and multiplicity (~33%), as well as reduced n-6 PUFA and enriched n-3 PUFA in tumor phospholipids relative to MMTV-neu(ndl)-YD5 control mice. The effect observed in hybrid progeny was similarly observed in n-3 PUFA diet fed mice.

CONCLUSION

Using complementary genetic and conventional dietary approaches we provide, for the first time, unequivocal experimental evidence that n-3 PUFA is causally linked to tumor prevention.

Effects of cow ghee (clarified butter oil) & soybean oil on carcinogen-metabolizing enzymes in rats

BACKGROUND & OBJECTIVES

Our previous study showed that cow ghee relative to soybean oil had a protective effect against carcinogen induced mammary cancer in rats. The objective of this study was to elucidate its biochemical mechanism.

METHODS

Two groups of 21 day old rats (20 each) were fed for 44 wk diet containing cow ghee or soybean oil (10%). Five animals from each group were sacrificed at 0 day and at 5, 21 and 44 wk for analysis of phase I and phase II pathways enzymes of carcinogen metabolism.

RESULTS

Dietary cow ghee relative to soybean oil decreased the activities of cytochrome P450 (CYP) enzymes, CYP1A1, CYP1A2, CYP1B1 and CYP2B1, responsible for activation of carcinogen in liver. Carcinogen detoxification activities of uridinediphospho-glucuronosyl transferase (UDPGT) and quinone reductase (QR) in liver, and γ-glutamyltranspeptidase (GGTP) and QR in mammary tissue were significantly higher in cow ghee fed rats than in soybean oil fed rats. The hepatic GGTP activity decreased on soybean oil diet; while in cow ghee group it remained unaffected.

INTERPRETATION & CONCLUSIONS

Our findings show that dietary cow ghee compared to soybean oil downregulates the enzyme activities responsible for carcinogen activation in liver and upregulates carcinogen detoxification activities in liver and mammary tissues.

Breast cancer in the Arctic--changes over the past decades

The purpose of this study is to review the current literatures on breast cancer (BC) in the Arctic, especially the trends in incidence during the last decades and the possible explanations. The design of this study is a literature review. The scientific literature concerning BC were reviewed, especially focusing on the Arctic and the special conditions that exist in this region. Breast cancer incidence is increasing all over the world, including in the Arctic. The enormous transition in health conditions and lifestyle in the Arctic might be contributing to the known risk factors. In Greenland, the age at menarche has diminished by 3 years during the course of 100 years, and the number of children per women as well as the duration of breastfeeding is decreasing. Obesity and intake of saturated fat is increasing and the intake of traditional food rich in unsaturated fat and vitamin D decreasing. Smoking and alcohol consumption in the Arctic has been relatively high but is now decreasing. More focus on genetic susceptibility in relation to BC has identified the specific BRCA1 founder mutation in the Greenlandic population, which might appear to be an important risk factor. However, the known established risk factors alone cannot account for the increasing trend observed. Studies suggest that environmental contaminants such as persistent organic pollutants (POPs) including perfluorinated compounds increase the risk of BC possibly in conjunction with certain genetic polymorphisms involved in carcinogen activation. The lipophilic POPs such as polychlorinated biphenyls and organochlorine pesticides are found at very high levels in the Arctic population. Several factors can explain the increasing incidence of BC in the Arctic. The transition in lifestyle and health conditions unfortunately increases the known risk factors of BC. Moreover, the population of the Arctic might show up to be especially vulnerable because of the contemporary high burden of POPs and genetic susceptibility.