Dietary flaxseed enhances the inhibitory effect of tamoxifen on the growth of estrogen-dependent human breast cancer (mcf-7) in nude mice

The Effects of Flaxseed Consumption on Glycemic Control in Native American Postmenopausal Women with Hyperglycemia and Hyperlipidemia

Glucose control in postmenopausal women is influenced by many factors, such as hormones, lifestyle variables, and genetics. Limited data exist on the effect of whole flaxseed on glucose status in postmenopausal Native American women. The aim of this study was to investigate the glucose management effect of a flaxseed dietary intervention on postmenopausal Native American women. In this study, 55 Native American postmenopausal women (aged 47-63 years) with borderline hyperglycemia (>100 and <126 mg/dL) and mild to moderate hypercholestorolemia (≥200 to ≤380 mmol/L), who were not on hormone replacement therapy, were enrolled. Participants were randomly assigned to one of the three dietary regimens (control, flaxseed, and flaxseed + fiber) for three months, receiving interventions in the form of bread, muffins, and flaxseed powder. Despite daily consumption of flaxseed across diverse food formats, no significant changes in glucose (p = 0.3, p = 0.2), insulin levels (p = 0.59, p = 0.9), or HOMA-IR (p = 0.84, p = 0.66) were observed compared to their respective baseline values within the flaxseed and flaxseed + fiber groups, respectively. Conversely, the control group showed a significant rise in final glucose values from baseline (p = 0.01). However, the incorporation of ground flaxseed into low-glycemic foods holds potential for beneficial effects through maintaining glucose status among postmenopausal Native American women. This research provides critical insights into the effects of flaxseed, emphasizing the need for continued exploration to understand its role in supporting glucose management among postmenopausal Native American women. Further exploration is required to investigate the potential long-term impact and the use of flaxseed in managing glucose levels in this demographic.

Medicinal Herbs Used in Traditional Management of Breast Cancer: Mechanisms of Action

Background: Breast cancer is one of the principal causes of death among women and there is a pressing need to develop novel and effective anti-cancer agents. Natural plant products have shown promising results as anti-cancer agents. Their effectiveness is reported as decreased toxicity in usage, along with safety and less recurrent resistances compared with hormonal targeting anti-cancer agents. Methods: A literature search was conducted for all English-language literature published prior to June 2020. The search was conducted using electronic databases, including PubMed, Embase, Web of Science, and Cochrane Library. The search strategy included keywords such as breast cancer, herbs, anti-cancer biologically active components, clinical research, chemotherapy drugs amongst others. Results: The literature provides documented evidence of the chemo-preventative and chemotherapeutic properties of Ginseng, garlic (Allium sativum), Black cohosh (Actaea racemose), Tumeric (Curcuma longa), Camellia sinenis (green tea), Echinacea, Arctium (burdock), Flaxseed (Linum usitatissimum) and Black Cumin (Nigella sativa). Conclusions: The nine herbs displayed anti-cancer properties and their outcomes and mechanisms of action include inhibition of cell proliferation, angiogenesis and apoptosis as well as modulation of key intracellular pathways. However, more clinical trials and cohort human studies should be conducted to provide key evidence of their medical benefits.

Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry, Pharmacokinetics, and Molecular Targets

Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

The Effect of Flaxseed in Breast Cancer: A Literature Review

Breast cancer is one of the most common cancers and the second most responsible for cancer mortality worldwide. In 2014, in Portugal approximately 27,200 people died of cancer, of which 1,791 were women with breast cancer. Flaxseed has been one of the most studied foods, regarding possible relations to breast cancer, though mainly in experimental studies in animals, yet in few clinical trials. It is rich in omega-3 fatty acids, α-linolenic acid, lignan, and fibers. One of the main components of flaxseed is the lignans, of which 95% are made of the predominant secoisolariciresinol diglucoside (SDG). SDG is converted into enterolactone and enterodiol, both with antiestrogen activity and structurally similar to estrogen; they can bind to cell receptors, decreasing cell growth. Some studies have shown that the intake of omega-3 fatty acids is related to the reduction of breast cancer risk. In animal studies, α-linolenic acids have been shown to be able to suppress growth, size, and proliferation of cancer cells and also to promote breast cancer cell death. Other animal studies found that the intake of flaxseed combined with tamoxifen can reduce tumor size to a greater extent than taking tamoxifen alone. Additionally, some clinical trials showed that flaxseed can have an important role in decreasing breast cancer risk, mainly in postmenopausal women. Further studies are needed, specifically clinical trials that may demonstrate the potential benefits of flaxseed in breast cancer.

Cambogin exerts anti-proliferative and pro-apoptotic effects on breast adenocarcinoma through the induction of NADPH oxidase 1 and the alteration of mitochondrial morphology and dynamics

Cambogin, a bioactive polycyclic polyprenylated acylphoroglucinol (PPAP) derived from the Garcinia genus, possesses proapoptotic effect in medulloblastoma and breast cancer cells. We have previously demonstrated that the proapoptotic effect of cambogin is driven by the production of reactive oxygen species (ROS). Here we have shown that the inhibitory effect of cambogin on cell proliferation is associated with the loss of mitochondrial transmembrane potential (ΔΨ_m) and mitochondrial fragmentation. Cambogin also promotes the mutual complex formation of the membrane-bound subunit p22^phox of NADPH oxidase 1 (NOX1), as well as the phosphorylation of the cytosolic subunit p47^phox, subsequently enhancing membrane-bound NOX1 activity, which leads to increases in intracellular and mitochondrial levels of O₂^.- and H₂O₂. Pharmacological inhibition of NOX1 using apocynin (pan-NOX inhibitor), ML171 (NOX1 inhibitor) or siRNA against NOX1 prevents the increases in O₂^.- and H₂O₂ levels and the anti-proliferative effect of cambogin. Antioxidants, including SOD (superoxide dismutase), CAT (catalase) and EUK-8, are also able to restore cell viability in the presence of cambogin. Besides, cambogin increases the dissociation of thioredoxin-1 (Trx1) from ASK1, switching the inactive form of ASK1 to the active kinase, subsequently leads to the phosphorylation of JNK/SAPK, which is abolished upon ML171 treatment. The proapoptotic effect of cambogin in breast cancer cells is also aggravated upon knocking down Trx1 in MCF-7 cells. Taken in conjunction, these data indicate that the anti-proliferative and pro-apoptotic effect of cambogin is mediated via inducing NOX1-dependent ROS production and the dissociation of ASK1 and Trx1.

Flaxseed Lignans Enhance the Cytotoxicity of Chemotherapeutic Agents against Breast Cancer Cell Lines MDA-MB-231 and SKBR3

Systemic cytotoxic chemotherapy remains the mainstay of metastatic breast cancer; however, prognosis and overall survival is unfavorable due to inadequate treatment response and/or unacceptable toxicity. Natural compounds and their active metabolites receive increasing attention as possible adjuvant therapy with cancer chemotherapeutics to improve treatment response, survival rates, and quality of life of breast cancer patients. This study investigated the combination of flaxseed lignans (Secoisolariciresinol and Enterolactone) with classic chemotherapeutic agents (Docetaxel, Doxorubicin, and Carboplatin) with different mechanisms of action to determine whether flaxseed lignans could enhance the cytotoxic effect of such drugs in the metastatic breast cancer cell lines, SKBR3 and MDA-MB-231. The experimental data suggests that flaxseed lignans significantly enhanced the ability of chemotherapeutic agents to cause cytotoxicity in SKBR3 and MDA-MB-231 breast cancer cells. A three compound combination study found that enterolactone and metformin together in combination with relatively low concentrations of chemotherapeutic drugs were able to significantly decrease cancer cell viability, compared to low concentrations of the individual chemotherapeutic drug alone. Our in vitro evaluation suggests a future direction in improving chemotherapeutic efficacy in breast cancer by adjuvant therapy with the flaxseed lignans.

Chitosan-Coated Cinnamon/Oregano-Loaded Solid Lipid Nanoparticles to Augment 5-Fluorouracil Cytotoxicity for Colorectal Cancer: Extract Standardization, Nanoparticle Optimization, and Cytotoxicity Evaluation

This study aimed to coat lipid-based nanocarriers with chitosan to encapsulate nutraceuticals, minimize opsonization, and facilitate passive-targeting. Phase one was concerned with standardization according to the World Health Organization. Qualitative analysis using liquid chromatography-high-resolution mass spectrometry (LC-HRMS/MS) investigated the active constituents, especially reported cytotoxic agents. Cinnamaldehyde and rosmarinic acid were selected to be quantified using high-performance liquid chromatography. Phase two was aimed to encapsulate both extracts in solid lipid nanoparticles (core) and chitosan (shell) to gain the advantages of both materials properties. The developed experimental model suggested an optimum formulation with 2% lipid, 2.3% surfactant, and 0.4% chitosan to achieve a particle size of 254.77 nm, polydispersity index of 0.28, zeta potential of +15.26, and entrapment efficiency percentage of 77.3% and 69.1% for cinnamon and oregano, respectively. Phase three was focused on the evaluation of cytotoxic activity unencapsulated/encapsulated cinnamon and oregano extracts with/without 5-fluorouracil on HCT-116 cells. This study confirmed the success of the suggested combination with 5-fluorouracil for treating human colon carcinoma with a low dose leading to decreasing side effects and allowing uninterrupted therapy.

Flaxseed Alone or in Combination with Tamoxifen Inhibits MCF-7 Breast Tumor Growth in Ovariectomized Athymic Mice with High Circulating Levels of Estrogen

Flaxseed (FS) is rich in mammalian lignan precursors and α-linolenic acid, which have been suggested as having anticancer effects. Previous studies have shown that 10% FS inhibits the growth of human estrogen–dependent breast cancer (MCF-7) in athymic mice, and it enhances the inhibitory effect of tamoxifen (TAM). This study determined whether the effect of FS, alone or in combination with TAM, is dose dependent, and it explored the potential mechanism of action. Ovariectomized athymic mice with estradiol (E2) supplementation (1.7 mg/pellet, 60-day release) and established MCF-7 tumors were treated with basal diet control (0FS), 5% FS (5FS), 10% FS (10FS), and TAM (TAM/ 0FS; 5 mg/pellet, 60-day release), alone or in combination (TAM/ 5FS and TAM/10FS) for 8 weeks. Compared with control, 5FS and 10FS significantly inhibited tumor growth by 26% and 38%, respectively. TAM/0FS had an effect similar to the 10FS. TAM/ 5FS and TAM/10FS, respectively, induced significant 48% and 43% reductions in tumor size compared with 0FS, and 18% and 10% reductions compared with TAM/0FS. The relative uterine weight was significantly lower in all TAM groups compared with the control. The reduction of tumor growth resulted from decreased cell proliferation and increased cell apoptosis. TAM/ 5FS caused a significantly higher expression of estrogen receptor-α (ERα) compared with 5FS and TAM/0FS, whereas TAM/10FS had a higher ERα than 10FS and TAM/0FS. Compared with the control, progesterone receptor (PgR) expression was significantly reduced in all treatment groups, but insulin-like growth factor-1 (IGF-1) expression was reduced only by 10FS, TAM/5FS and TAM/10FS. Tumor cell proliferation was significantly positively associated with expression of PgR and IGF-1 and negatively associated with apoptosis and ERα. Apoptosis was only associated with ERα. In conclusion, FS inhibited MCF-7 tumor growth in a dose-dependent manner and enhanced the inhibitory effect of TAM due to the modulation of ER and growth factor signal transduction pathways.

Flaxseed and its components differentially affect estrogen targets in pre-neoplastic hen ovaries

Flaxseed has been studied for decades for its health benefits that include anti-cancer, cardio-protective, anti-diabetic, anti-inflammatory properties. The biologically active components that mediate these effects are the omega-3 fatty acids and the lignan, secoisolariciresinol diglucoside. We have previously shown that whole flaxseed supplemented diet decreases the severity and incidence of ovarian cancer while a 15% dose of flaxseed is most protective against inflammation and estrogen-induced chemical and genotoxicity. The objective of this study was to dissect the independent effects of the two flaxseed components on estrogen signaling and metabolism. Two and half year old hens were fed either a control diet, 15% whole flaxseed diet, defatted flax meal diet or 5% flax oil diet for 3 months after which the animals were sacrificed and blood and tissues were harvested. Whole flaxseed diet caused a decrease in expression of ERα. ERα target gene expression was assessed using RT(2) profiler PCR array. Some targets involved in the IGF/insulin signaling pathway (IRS1, IGFBP4, IGFBP5) were downregulated by flaxseed and its components. Flaxseed diet also downregulated AKT expression. A number of targets related to NF-kB signaling were altered by flaxseed diet including a series of targets implicated in cancer. Whole flaxseed diet also affected E2 metabolism by increasing CYP1A1 expression with a corresponding increase in the onco-protective E2 metabolite, 2-methoxyestradiol. The weak anti-estrogens, enterolactone, enterodiol and 2-methoxyestradiol, might be working synergistically to generate a protective effect on the ovaries from hens on whole flaxseed diet by altering the estrogen signaling and metabolism.

Role of dietary bioactive natural products in estrogen receptor-positive breast cancer

Estrogen receptor (ER)-positive breast cancer, including luminal-A and -B, is the most common type of breast cancer. Extended exposure to estrogen is associated with an increased risk of breast cancer. Both ER-dependent and ER-independent mechanisms have been implicated in estrogen-mediated carcinogenesis. The ER-dependent pathway involves cell growth and proliferation triggered by the binding of estrogen to the ER. The ER-independent mechanisms depend on the metabolism of estrogen to generate genotoxic metabolites, free radicals and reactive oxygen species to induce breast cancer. A better understanding of the mechanisms that drive ER-positive breast cancer will help optimize targeted approaches to prevent or treat breast cancer. A growing emphasis is being placed on alternative medicine and dietary approaches toward the prevention and treatment of breast cancer. Many natural products and bioactive compounds found in foods have been shown to inhibit breast carcinogenesis via inhibition of estrogen induced oxidative stress as well as ER signaling. This review summarizes the role of bioactive natural products that are involved in the prevention and treatment of estrogen-related and ER-positive breast cancer.

Current Management Strategies in Breast Cancer by Targeting Key Altered Molecular Players

Breast cancer is the second largest disease affecting women worldwide. It remains the most frequently reported and leading cause of death among women in both developed and developing countries. Tamoxifen and raloxifene are commonly used selective estrogen receptor modulators for treatment of breast cancer in women with high risk, although resistance occurs by tamoxifen after 5 years of therapy and both drugs cause uterine cancer and thromboembolic events. Aromatase inhibitors (AIs) are one of the optional modes used for breast cancer treatment. The combination of AIs along with tamoxifen can also be beneficial. Various therapeutic agents from different sources are being studied, which further need to be improved for potential outcome. For this, clinical trials based on large number of patients with optimal dose and lesser side effects have to be more in practice. Despite the clinical trials going on, there is need of better molecular models, which can identify high risk population, new agents with better benefit having less side effects, and improved biomarkers for treating breast cancer.

Stereological study of the effect of black olive hydroalcoholic extract on osteoporosis in vertebra and tibia in ovariectomized rats

A cocktail of many different antioxidants might be more effective than supplementation with a single molecule, and it closely resembles the natural environment in which active compounds were found. This is the first study well-grounded in stereological examination that showed that black olive extract effectively can ameliorate the quantitative changes of the bone structure and prevented bone loss in this osteoporosis animal model.

INTRODUCTION

The aim of this study was to quantitatively evaluate the effects of black olive extract consumption on treatment of ovariectomized (OVX) induced osteoporosis in rats. This is the first study well-grounded in stereological examination.

METHODS

Ninety adult rats were allocated to control, sham-operated, OVX, and olive-supplemented OVX groups (received 250-, 500-, and 750-mg/kg body weight black olive hydroalcoholic extract orally) for 16 weeks. At the end of the experiment, blood samples were collected, and plasma levels of calcium, phosphorus, and alkaline phosphatase were assayed. Then, the specimens from both the tibia and fifth lumbar vertebra (L5) bones were processed, and stereological analysis was performed.

RESULTS

Administration of extract resulted in decrease of alkaline phosphatase level during the treatment. After treatment of OVX rats with three doses of extract, the total number of the osteocytes revealed an increment in 500- and 750-mg/kg treated groups in comparison to the OVX group. This increment was significant only in L5. Compared to the OVX group, a significant increase was observed in the number of osteoblastsin L5 vertebra in three doses of extract-treated groups. However, this increment in tibia was statistically significant only in 750-mg/kg black olive hydroalcoholic extract-treated group. Moreover, the number of osteoclast cells were significantly decreased in vertebra and tibia in the treated groups compared to the OVX group (P < 0.05).

CONCLUSION

Black olive hydroalcoholic extract effectively can ameliorate the quantitative changes of the bone structure and prevented bone loss in this osteoporosis animal model. Thus, it can be a promising candidate for treatment of accelerated bone loss especially in postmenopausal osteoporosis.

Cambogin Induces Caspase-Independent Apoptosis through the ROS/JNK Pathway and Epigenetic Regulation in Breast Cancer Cells

Cambogin is a polycyclic polyprenylated acylphoroglucinol (PPAP) from the Garcinia genus, which has been used traditionally for cancer treatment across Southeastern Asia. In this study, we found that cambogin inhibited breast cancer cell proliferation and induced cell apoptosis in vitro. Cambogin induced the activation of the caspase-independent mitochondrial apoptotic pathway, as indicated by an increase in the ratio of Bax/Bcl-2 and the nuclear translocation of apoptosis inducing factor (AIF). Two-dimensional gel electrophoresis and mass spectrometry revealed that the expression of proteins involving in the radical oxygen species (ROS) pathway was among the most affected upon cambogin treatment. Cambogin enhanced cellular ROS production, and induced the activation of the ASK1-MKK4/MKK7-JNK/SAPK signaling pathway. Pretreatment with ROS scavenger N-acetylcysteine (NAC), an antioxidant, or the JNK inhibitor SP600125 was able to restore cell viability in the presence of cambogin. Importantly, cambogin treatment led to the activation of activating transcription factor-2 (ATF-2) and the trimethylation of histone H3K9 in the activator protein 1 (AP-1) binding region of the Bcl-2 gene promoter. Finally, cambogin exhibited a potential antitumor effect in MCF-7 breast cancer xenografts without apparent toxicity. Taken in conjunction, the present study indicates that cambogin can induce breast adenocarcinoma cell apoptosis and therefore represents therapeutic potential for cancer treatment.

Synergistic effect of combinatorial treatment with curcumin and mitomycin C on the induction of apoptosis of breast cancer cells: a cDNA microarray analysis

In order to explore the synergistic mechanisms of combinatorial treatment using curcumin and mitomycin C (MMC) for breast cancer, MCF-7 breast cancer xenografts were conducted to observe the synergistic effect of combinatorial treatment using curcumin and MMC at various dosages. The synergistic mechanisms of combinatorial treatment using curcumin and MMC on the inhibition of tumor growth were explored by differential gene expression profile, gene ontology (GO), ingenuity pathway analysis (IPA) and Signal-Net network analysis. The expression levels of selected genes identified by cDNA microarray expression profiling were validated by quantitative RT-PCR (qRT-PCR) and Western blot analysis. Effect of combinatorial treatment on the inhibition of cell growth was observed by MTT assay. Apoptosis was detected by flow cytometric analysis and Hoechst 33258 staining. The combinatorial treatment of 100 mg/kg curcumin and 1.5 mg/kg MMC revealed synergistic inhibition on tumor growth. Among 1501 differentially expressed genes, the expression of 25 genes exhibited an obvious change and a significant difference in 27 signal pathways was observed (p<0.05). In addition, Mapk1 (ERK) and Mapk14 (MAPK p38) had more cross-interactions with other genes and revealed an increase in expression by 8.14- and 11.84-fold, respectively during the combinatorial treatment by curcumin and MMC when compared with the control. Moreover, curcumin can synergistically improve tumoricidal effect of MMC in another human breast cancer MDA-MB-231 cells. Apoptosis was significantly induced by the combinatorial treatment (p<0.05) and significantly inhibited by ERK inhibitor (PD98059) in MCF-7 cells (p<0.05). The synergistic effect of combinatorial treatment by curcumin and MMC on the induction of apoptosis in breast cancer cells may be via the ERK pathway.

Flaxseed and its lignan and oil components: can they play a role in reducing the risk of and improving the treatment of breast cancer?

Flaxseed (FS), rich in the phytoestrogen lignans and α-linolenic acid-rich oil, has been suggested to have an anticancer effect. Questions remain whether FS and its lignan and oil components are effective in reducing breast cancer risk and tumour growth, and can interact beneficially with breast cancer drugs. To find answers, in vitro, animal, observational, and clinical studies on FS and its lignan and oil components were reviewed. The majority of studies in various rodent models show that 2.5%–10% FS diet or the equivalent amount of lignan or oil reduces tumour growth. Ten percent FS and equivalent lignans do not interfere with but rather increase the effectiveness of tamoxifen (80 mg/day) while the 4% FS oil increases trastuzumab/Herceptin (2.5 mg/kg) effectiveness. Observational studies show that FS and lignan intake, urinary excretion, or serum levels are associated with reduced risk, particularly in postmenopausal women. Lignans reduce breast cancer and all-cause mortality by 33%–70% and 40%–53%, respectively, without reducing tamoxifen effectiveness. Clinical trials show that FS (25 g/day with 50 mg lignans; 32 days) reduces tumour growth in breast cancer patients and lignans (50 mg/day; 1 year) reduces risk in premenopausal women. Mechanisms include decreased cell proliferation and angiogenesis and increased apoptosis through modulation of estrogen metabolism and estrogen receptor and growth factor receptor signalling pathways. More clinical trials are needed but current overall evidence indicates that FS and its components are effective in the risk reduction and treatment of breast cancer and safe for consumption by breast cancer patients.

A pilot study comparing the effect of flaxseed, aromatase inhibitor, and the combination on breast tumor biomarkers

Use of complementary approaches is common among breast cancer survivors. Potential interactions between aromatase inhibitors (AI) and high phytoestrogen foods, such as flaxseed (FS), are not often described. We conducted a pilot 2 × 2 factorial, randomized intervention study between tumor biopsy and resection, in 24 postmenopausal women with estrogen receptor positive (ER+) breast cancer, to assess the effects of FS and anastrozole, and possible interactions between them, on serum steroid hormone and tumor-related characteristics associated with long-term survival (Roswell Park Cancer Institute, 2007-2010). The effect of each treatment vs. placebo on outcomes was determined by linear regression adjusting for pretreatment measure, stage, and grade. Although not statistically significant, mean ERβ expression was approximately 40% lower from pre- to postintervention in the FS + AI group only. We observed a statistically significant negative association (β ± SE -0.3 ± 0.1; P = 0.03) for androstenedione in the FS + AI group vs. placebo and for DHEA with AI treatment (β ± SE -1.6 ± 0.6; P = 0.009). Enterolactone excretion was much lower in the FS + AI group compared to the FS group. Our results do not support strong effects of FS on AI activity for selected breast tumor characteristics or serum steroid hormone levels but suggest AI therapy might reduce the production of circulating mammalian lignans from FS.

Role of phytoestrogenic oils in alleviating osteoporosis associated with ovariectomy in rats

The objective of this study was to elucidate the effect of soybean oil (SbO) and sesame oil (SO) supplemented diets on bone biomarkers changes in OVX (ovariectomized) rats. The current data exhibited significant decrease in BMD (bone mineral density), accompanied with marked depletion in the level of Ca, P and Mg in both serum and bone of OVX rats. Also, serum estrogen, total protein, HDL-C (high density lipoprotein cholesterol), bone NO levels were decreased in OVX rats. However, a significant increase in the level of serum TL (total lipids), TC (total cholesterol), TG (triglycerides), LDL-C (low density lipoprotein cholesterol), VLDL-C (very low density lipoprotein cholesterol), urine minerals (Ca, P, Mg), as well as serum, bone and urine ALP (alkaline phosphatase) and ACP (acid phosphatase) activity were recorded in OVX rats. Further changes were also detected by the increased level of urine hydroxyproline, serum parathyroid hormone and osteocalcin, as well as urea and creatinine level in both serum and urine. On the other hand, when OVX rats were fed on SbO (soy bean oil) (15 % w/w) or SO (sesame oil) (10 % w/w) supplemented diets, the data recorded a significant improvement in all the above mentioned parameters. So, it can be concluded that consumption of SbO or SO supplemented diets might be considered as a functional food for retarding risks of osteoporosis associated with estrogen deficiency in OVX states.

The multifaceted effects of omega-3 polyunsaturated Fatty acids on the hallmarks of cancer

Omega-3 polyunsaturated fatty acids, in particular eicosapentaenoic acid, and docosahexaenoic acid have been shown to have multiple beneficial antitumour actions that affect the essential alterations that dictate malignant growth. In this review we explore the putative mechanisms of action of omega-3 polyunsaturated fatty acid in cancer protection in relation to self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion, and how these will hopefully translate from bench to bedside.

Flaxseed does not enhance the estrogenic effect of low-dose estrogen therapy on markers of uterine health in ovariectomized rats

Flaxseed (FS) is an oilseed rich in phytoestrogens and n-3 polyunsaturated fatty acids, compounds that may attenuate bone loss during aging. We previously demonstrated using the ovariectomized (OVX) rat model of postmenopausal osteoporosis that 10% dietary FS combined with low-dose estrogen therapy (LD) preserves vertebral bone mass and strength more so than either treatment alone. However, it was prudent to also consider the effect of this intervention on uterine tissue as LD, and possibly FS, may have estrogenic, and thus negative, effects on uterine tissue. The present study investigated if FS enhances the estrogenic effect of LD on markers of uterine health in OVX rats. Three-month-old rats were randomized to groups: (1) SHAM, (2) OVX, (3) OVX+FS, (4) OVX+LD, or (5) OVX+FS+LD. Ground FS was added to the AIN-93M diet (100 g/kg of diet), and LD was delivered by subcutaneous implant (0.42 μg of 17β-estradiol/kg of body weight/day) to mimic LD in postmenopausal women. After 12 weeks, histological analyses of uterine tissue demonstrated flattened or cuboidal luminal epithelia organized in a single layer in the OVX group, while FS, LD, and FS+LD induced a single layer of elongated luminal epithelia, columnar in shape. The SHAM group had the greatest epithelial mass. Cell proliferation was similar among all OVX groups. Therefore FS and FS+LD similarly induce estrogen-like effects on the morphology of luminal epithelia that are weaker than in the SHAM group without inducing cell proliferation in OVX rats. Thus, FS does not enhance the estrogenic effect of LD on markers of uterine health in OVX rats.

Dietary intakes of total and specific lignans are associated with clinical breast tumor characteristics

Dietary lignans may affect breast cancer by modifying tumor characteristics likely to affect prognosis. We investigated usual dietary intakes of total and specific lignans with tumor characteristics in 683 women with breast cancer and 611 healthy women without breast cancer enrolled in the Data Bank and BioRepository at Roswell Park Cancer Institute (RPCI). Clinicopathologic data were abstracted from the RPCI breast cancer database. Dietary lignan intakes were calculated from FFQ. OR and 95% CI were estimated with logistic regression adjusting for potential confounders and stratified by menopausal status. Women in the highest compared to the lowest tertile of total lignan intakes had a 40-50% lower odds of breast cancer regardless of menopausal status and substantially reduced odds of an invasive tumor, especially among premenopausal women [OR 0.48 (95% CI 0.26-0.86)]. Lignan intakes were inversely associated with odds of grade 3 tumors among premenopausal women. Lignan intakes were inversely associated with risk of estrogen receptor (ER) negative (ER(-)) breast cancer among premenopausal women [OR 0.16 (95% CI 0.03-0.44)] and particularly triple negative tumors [ER(-), progesterone receptor negative, HER2 negative; OR 0.16 (95% CI 0.04-0.62)]. There were significant differences in the contribution to these effects by specific lignans, especially matairesinol and lariciresinol. In summary, in this case-control study of dietary lignan intakes and breast cancer, we found that higher lignan intakes were associated with lower risks of breast cancer with more favorable prognostic characteristics. Future investigations are warranted to explore the strong associations observed with ER(-) cancer in premenopausal women.

Comparative effects of sesame seed lignan and flaxseed lignan in reducing the growth of human breast tumors (MCF-7) at high levels of circulating estrogen in athymic mice

Flaxseed (FS) has a breast tumor-reducing effect, possibly because of its high content of secoisolariciresinol diglucoside (SDG) lignan. Sesame seed (SS) is rich in the lignan sesamin (SES) but is non-protective. Both lignans are metabolized to estrogen-like enterodiol and enterolactone. The objective of this study was to differentiate the effects of SDG and SES on established human estrogen receptor-positive breast tumors (MCF-7) in athymic mice with high serum estrogen to help explain the different effects of FS and SS. Mice were fed for 8 wk the basal diet (BD, control) or BD supplemented with 1 g/kg SDG or SES. SES reduced palpable tumor size by 23% compared to control, whereas SDG did not differ from SES or control. Both treatments reduced tumor cell proliferation, but only SES increased apoptosis. SDG and SES reduced human epidermal growth factor receptor 2 and endothelial growth factor receptor expressions, but only SES reduced downstream pMAPK. Neither treatment affected IGF-1R, vascular endothelial growth factor receptor-2, Akt, pAkt, or MAPK of the growth factor signaling pathway. Thus, at high serum estrogen levels, SDG may not account for the tumor reducing effect of FS. SES was more effective than SDG in reducing breast tumor growth, but its effect may have been lost when consumed as a component of SS.

Curcumin enhanced antiproliferative effect of mitomycin C in human breast cancer MCF-7 cells in vitro and in vivo

AIM

To investigate the efficacy of mitomycin C (MMC) in combination with curcumin in suppressing human breast cancer in vitro and in vivo.

METHODS

Human breast cancer MCF-7 cells were used. Cell viability was measured using MTT assay. The cell cycle phase was detected with flow cytometric analysis. Cell cycle-associated proteins were examined using Western blot analysis. MCF-7 breast cancer xenografts were established to monitor tumor growth and cell cycle-associated protein expression.

RESULTS

Curcumin inhibited MCF-7 breast cancer cell viability in a concentration-dependent manner (IC(50) value=40 μmol/L). Similarly, MMC inhibited the cell viability with an IC(50) value of 5 μmol/L. Combined treatment of MMC and curcumin showed a synergistic antiproliferative effect. In the presence of curcumin (40 μmol/L), the IC(50) value of MMC was reduced to 5 μmol/L. In MCF-7 xenografts, combined administration of curcumin (100 mg/kg) and MMC (1-2 mg/kg) for 4 weeks produced significantly greater inhibition on tumor growth than either treatment alone. The combined treatment resulted in significantly greater G(1) arrest than MMC or curcumin alone. Moreover, the cell cycle arrest was associated with inhibition of cyclin D1, cyclin E, cyclin A, cyclin-dependent kinase 2 (CDK2) and CDK4, along with the induction of the cell cycle inhibitor p21 and p27 both in MCF-7 cells and in MCF-7 xenografts. These proteins were regulated through p38 MAPK pathway.

CONCLUSION

The results suggest that the combination of MMC and curcumin inhibits MCF-7 cell proliferation and cell cycle progression in vitro and in vivo via the p38 MAPK pathway.

Curcumin improves MMC-based chemotherapy by simultaneously sensitising cancer cells to MMC and reducing MMC-associated side-effects

Mitomycin C (MMC) potently suppresses tumour growth. However, its use is limited by its severe toxicity to the kidney and bone marrow. The purpose of this study is to investigate whether the chemoprevention agent curcumin can reduce MMC-associated side-effects and improve MMC efficacy in a breast cancer xenograft model. We first determined the effectiveness of combined MMC and curcumin to inhibit in vitro cell growth and to regress in vivo tumour outgrowth. We then investigated the mechanisms associated with MMC/curcumin-induced cell death by examining the effect of MMC/curcumin treatment on apoptosis, the activation of caspase-3, 8 and 9 and the expression of bcl-2 and bax. We also evaluated the ability of curcumin to alleviate MMC-associated side-effects by comparing the levels of creatinine/blood urea nitrogen (Cr/BUN) and glutamic oxalacetic transaminase/glutamic pyruvic transaminase (GPT/GOT) in serum between animals receiving MMC alone and MMC/curcumin. Curcumin significantly sensitised MCF-7 and MDA-MB-231 cells to MMC-induced cell death and improved MMC's ability to regress MCF-7 xenograft. MMC and curcumin together synergistically enhanced apoptosis in MCF-7 cells and the apoptosis most likely resulted from both the activation of caspases and modulation of bcl-2/bax expression. Most importantly, the inclusion of curcumin in MMC treatment decreased MMC-caused severe side-effects evidenced by significant improvement in the kidney function. Enhancing the tumoricidal effect of MMC, curcumin greatly reduces MMC-associated severe side-effects. Therefore, the combination treatment of MMC and curcumin may be of significant therapeutic benefit in treating breast cancer.

Investigation into the cancer protective effect of flaxseed in Tg.NK (MMTV/c-neu) mice, a murine mammary tumor model

The aim of the present study was to investigate whether low flaxseed doses relevant to human dietary exposure can prevent mammary tumors in transgenic Tg.NK mice, a model of breast cancer. Animals were exposed to flaxseed through the diet at human relevant levels. Tumor-related parameters and tumor development were evaluated. Hepatic cytochrome P450 and glutathione S-transferase activities were significantly reduced in animals receiving low flaxseed doses. An incidence of palpable tumors before sacrifice, a number of tumors per mouse, and a number of large tumors (>6 mm diameter) at necropsy were statistically significantly lower in the high flaxseed group compared to controls, suggesting a beneficial effect on tumor progression of small dietary doses of flaxseed. However, the number of tumor-bearing mice and multiplicity of tumors at necropsy were not statistically significantly lower compared to the controls. Thus, the effect of small dietary doses of flaxseed on mammary tumor development in Tg.NK mice remains to be established.

Effects of flaxseed lignan and oil on bone health of breast-tumor-bearing mice treated with or without tamoxifen

Previous studies showed that flaxseed lignan (secoisolariciresinol diglucoside, SDG) and oil (FO) inhibit established breast tumor growth in athymic mice with or without tamoxifen (TAM) treatment. TAM was found to increase bone mineral content (BMC) and density (BMD) in breast cancer patients. It is not known whether SDG or FO alone or combined with TAM affects bone health. Hence, the effects of SDG and FO, alone or in combination, on BMC, BMD, and biomechanical bone strength in ovariectomized athymic mice with established human breast tumors (MCF-7) treated with or without TAM were studied. In a factorial design, mice were divided into four non-TAM and four TAM groups. Each group consisted of mice fed a basal diet (BD), SDG (1 g/kg), FO (38.5 g/kg) or SDG + FO (combination) diets. The TAM group had TAM implants that provide a 5-mg TAM dose released over 60 d. TAM exerted an overall significant effect in increasing BMC, BMD, and biomechanical strength in femurs and lumbar vertebra. Without TAM treatment, SDG produced significant lower femur BMD (6%) while FO produced lower vertebrae BMC (8%) and BMD (6%). With TAM treatment, SDG and FO did not exert an effect on BMC and BMD at the femur or vertebra. SDG and FO produced no marked effect on biomechanical bone strength with or without TAM treatment. In conclusion, FS components did not significantly attenuate the positive effects on bone induced by TAM in this model system, indicating no apparent adverse effects on bone health.

Flaxseed cotyledon fraction reduces tumour growth and sensitises tamoxifen treatment of human breast cancer xenograft (MCF-7) in athymic mice

Dietary flaxseed (FS) inhibited the growth of human breast tumours and enhanced the effectiveness of tamoxifen (TAM) in athymic mice with low oestradiol (E2) levels. The present study determined whether the n-3 fatty acid-rich cotyledon fraction of FS (FC), alone or in combination with TAM, has a similar effect and thus can substitute for FS. In a 2 × 2 factorial design, ovariectomised mice with established oestrogen receptor (ER)-positive breast tumours (MCF-7) were treated as follows: groups 1 and 2 were fed the basal diet (BD, control) and FC diet (82 g FC/kg), respectively. Groups 3 and 4 with TAM implants (5 mg) were fed the BD and FC diet, respectively. At 8 weeks post-treatment, mice were euthanised, and tumours were analysed by immunohistochemistry and real-time PCR. BD, FC and FC/TAM groups significantly decreased tumour area, but the TAM group did not. Tumour regression in the FC/TAM group was greater compared to the TAM group. FC lowered cell proliferation but had no effect on apoptosis; the opposite was observed with TAM. FC suppressed mRNA expressions of pS2 and insulin-like growth factor 1 receptor (IGF-1R) and protein expressions of ERα, phosphospecific ERα, human epidermal growth factor receptor 2 (HER2), phosphospecific HER2 (pHER2) and amplified in breast 1 (AIB1), while TAM up-regulated mRNA expressions of Bcl2, progesterone receptor and IGF-1R and protein expression of pHER2, and down-regulated ERβ mRNA. FC modulated the effect of TAM on tumour growth biomarkers. In conclusion, FC reduced the growth of ER+human breast tumours at low circulating E2, alone and combined with TAM, in part through modulation of ER −  and growth factor-mediated signalling pathways; it may substitute for FS in increasing the effectiveness of TAM.

Canola oil inhibits breast cancer cell growth in cultures and in vivo and acts synergistically with chemotherapeutic drugs

Certain fatty acids in canola oil (CAN) have been associated with a reduced risk of breast cancer. This study assessed the effects of CAN on proliferation and death of human breast cancer cells in vitro and in vivo in chemically induced mammary carcinogenesis. We hypothesize that CAN reduces breast cancer cell growth by inducing cell death. In a series of in vitro experiments, human breast cancer T47D and MCF-7 cells were cultured and treated with CAN and two chemotherapeutic drugs, tamoxifen and cerulenin. Cell proliferation and caspase-3 and p53 activities were measured. Reduced cancer cell growth and increased expression of caspase-3 and p53 were seen in T47D and MCF-7 cells treated with CAN. Moreover, CAN showed synergistic cancer cell growth inhibition effects with tamoxifen and cerulenin. In a subsequent live animal experiment, 42 female Sprague-Dawley rats were randomly assigned to corn oil (CORN) or CAN diets, and mammary tumors were chemically induced by N-nitroso-N-methylurea. CAN-dieted rats had reduced tumor volumes and showed an increased survival rate as compared to CORN-dieted rats. We demonstrated that CAN has suppressive effects on cancer growth, and reduces tumor volumes. The results suggest that CAN may have inhibitory effects on breast cancer cell growth, and warrants further investigation of the synergistic effects of CAN with anti-cancer drugs.

Soy intake in association with menopausal symptoms during the first 6 and 36 months after breast cancer diagnosis

It has been suggested that soy food and its components may relieve menopausal symptoms (MPS) including hot flashes, night sweats, and vaginal dryness in healthy women. However, little is known about the effect of soy food intake on MPS in women with breast cancer. We examined associations of occurrence of MPS with soy food intake in 4,842 Chinese women aged 20-75 years who had non-metastatic breast cancer and had not used hormone replacement therapy. MPS were assessed at 6 and 36 months after cancer diagnosis using a standardized questionnaire, and associations with soy food intake were evaluated in multivariate regression analyses. Daily soy food intake was assessed at 6 months postdiagnosis and over the first 36 months postdiagnosis using a validated food frequency questionnaire. The prevalence of MPS was 56% at 6 months and 63% at 36 months postdiagnosis with the hotflash being the most common MPS (~44-55%). Hot flashes occurred mainly in premenopausal breast cancer patients who were in the highest quartile of isoflavone intake at 6 months postdiagnosis (OR = 1.20, 95% CI: 0.98-1.59) compared with the lowest quartile. This association was stronger at 36 months postdiagnosis (OR = 1.59, 95% CI: 1.02-2.48). We found no significant associations for any MPS, night sweats, or vaginal dryness. Neither tamoxifen use nor BMI modified the association between MPS and isoflavone intake. There was no evidence that soy food consumption reduced MPS among breast cancer patients. High soy intake may increase the prevalence of hotflashes among premenopausal patients. Our study suggests that soy acts as an estrogen antagonist in breast cancer patients.

Management of menopause-associated vasomotor symptoms: Current treatment options, challenges and future directions

Hot flashes are one of the most common and distressing symptoms associated with menopause, occurring in more than 75% of postmenopausal women. They are especially problematic in breast cancer patients since some breast cancer therapies can induce hot flashes. For mild hot flashes, it is proposed that behavioral modifications are the first step in management. Hormonal therapies, including estrogens and progestogens, are the most well known effective agents in relieving hot flashes; however, the safety of these agents is controversial. There is an increasing amount of literature on nonhormonal agents for the treatment of hot flashes. The most promising data regard newer antidepressant agents such as venlafaxine, which reduces hot flashes by about 60%. Gabapentin is another nonhormonal agent that is effective in reducing hot flashes. While many complimentary therapies, including phytoestrogens, black cohosh, and dehydroepiandrosterone, have been explored for the treatment of hot flashes; none can be recommended at this time. Furthermore, there is a lack of strong evidence to support exercise, yoga, or relaxation for the treatment of hot flashes. Paced respirations and hypnosis appear to be promising enough to warrant further investigation. Another promising nonpharmacological therapy, currently under investigation, involves a stellate ganglion block.

Meta-analyses of lignans and enterolignans in relation to breast cancer risk

BACKGROUND

Epidemiologic studies that examined whether lignans, the most important class of phytoestrogens in the Western diet, protect against breast cancer have yielded inconsistent results.

OBJECTIVE

In this study, we conducted meta-analyses on the association between lignans and breast cancer risk.

DESIGN

We performed a systematic MEDLINE search to identify epidemiologic studies published between 1997 and August 2009. We calculated pooled risk estimates (REs) for total lignan exposure, dietary lignan intake, enterolignan exposure, and blood or urine concentrations of enterolactone and according to menopausal and estrogen receptor (ER) status of tumors.

RESULTS

We included 21 studies (11 prospective cohort studies and 10 case-control studies) in the meta-analyses. Lignan exposure was not associated with an overall breast cancer risk (RE: 0.92; 95% CI: 0.81, 1.02; P for heterogeneity = 0.004). However, in postmenopausal women, high lignan intake was associated with a significant reduced risk of breast cancer (13 studies; RE: 0.86; 95% CI: 0.78, 0.94; P for heterogeneity = 0.32). Breast cancer risk was also inversely associated with enterolignan exposure (4 studies; RE: 0.84; 95% CI: 0.71, 0.97) but not with blood or urine enterolactone concentrations. The associations were not significantly different between ER-status subgroups (6 studies).

CONCLUSIONS

High lignan exposure may be associated with a reduced breast cancer risk in postmenopausal women. Additional work is warranted to clarify the association between lignan exposure and breast cancer risk.

Flaxseed and pure secoisolariciresinol diglucoside, but not flaxseed hull, reduce human breast tumor growth (MCF-7) in athymic mice

Previous studies have shown that dietary flaxseed (FS) can reduce the growth of established human breast tumors in athymic mice with low circulating estrogen concentrations. In this study, we determined the effect of FS compared with pure lignan at the level it is present in FS [secoisolariciresinol diglucoside (SDG)] and to the lignan-rich fraction [FS hull (FH)] on human breast tumor growth and their potential mechanisms of action. Ovariectomized, athymic mice, each with an implanted 17 beta-estradiol (E2) pellet (0.36 mg), were injected with human estrogen receptor (ER) positive breast cancer cells (MCF-7). When tumors were established, the E2 pellet was removed. Mice were fed either the control basal diet (BD), FS (100 g/kg diet), SDG (1 g/kg diet), or FH (18 g/kg diet) for 8 wk. Compared with the BD, FS and SDG significantly decreased the palpable tumor size, but effects of FS, SDG, and FH did not differ from one another. All treatments significantly inhibited cell proliferation, but only FS and SDG induced significantly higher apoptosis. Both FS and SDG significantly decreased mRNA expressions of Bcl2, cyclin D1, pS2, ERalpha, and ERbeta, epidermal growth factor receptor, and insulin-like growth factor receptor. FS also reduced human epidermal growth factor receptor 2 mRNA and SDG decreased phospho-specific mitogen-activated protein kinase expression. FH did not significantly reduce these biomarkers. In conclusion, pure SDG has a similar effect as FS in reducing tumor growth and in mechanisms of action, including downregulating ER- and growth factor-mediated cell signaling. The lesser effects of FH indicate a need for a higher dose to be more effective.

Effects of dietary flaxseed on intestinal tumorigenesis in Apc(Min) mouse

Dietary flaxseed has been shown to prevent azoxymethane (AOM)-induced colorectal cancers in male Fisher rats. The present study was designed to investigate the chemopreventive effects of dietary flaxseed on the development of intestinal tumors in Apc(Min) mice. Apc(Min) mice were divided into five different groups, fed with control (AIN-93M meal), corn meal, flaxseed meal, corn oil, and flaxseed oil supplemented diets. Results showed that dietary flaxseed significantly decreased (P < 0.05) tumor multiplicity and size in the small intestine and colon as compared to control, corn-treated groups. Intestine, colon, and serum samples of corn-treated groups showed higher levels of omega -6 fatty acids, whereas the flaxseed treated groups exhibited higher levels of omega -3 fatty acids. Lignans were detected in the serum, intestine, and colon samples for flaxseed meal group. COX-1 and COX-2 expression in the colon samples from the flaxseed meal group were significantly lower (P < 0.05) as compared to the corn meal group. Dietary flaxseed may be chemopreventive for intestinal tumor development in Apc(Min) mice possibly by increasing omega -3 fatty acid levels, lignans, and decreasing COX-1 and COX-2 levels.

Flaxseed supplementation (not dietary fat restriction) reduces prostate cancer proliferation rates in men presurgery

BACKGROUND

Prostate cancer affects one of six men during their lifetime. Dietary factors are postulated to influence the development and progression of prostate cancer. Low-fat diets and flaxseed supplementation may offer potentially protective strategies.

METHODS

We undertook a multisite, randomized controlled trial to test the effects of low-fat and/or flaxseed-supplemented diets on the biology of the prostate and other biomarkers. Prostate cancer patients (n = 161) scheduled at least 21 days before prostatectomy were randomly assigned to one of the following arms: (a) control (usual diet), (b) flaxseed-supplemented diet (30 g/d), (c) low-fat diet (<20% total energy), or (d) flaxseed-supplemented, low-fat diet. Blood was drawn at baseline and before surgery and analyzed for prostate-specific antigen, sex hormone-binding globulin, testosterone, insulin-like growth factor-I and binding protein-3, C-reactive protein, and total and low-density lipoprotein cholesterol. Tumors were assessed for proliferation (Ki-67, the primary endpoint) and apoptosis.

RESULTS

Men were on protocol an average of 30 days. Proliferation rates were significantly lower (P < 0.002) among men assigned to the flaxseed arms. Median Ki-67-positive cells/total nuclei ratios (x100) were 1.66 (flaxseed-supplemented diet) and 1.50 (flaxseed-supplemented, low-fat diet) versus 3.23 (control) and 2.56 (low-fat diet). No differences were observed between arms with regard to side effects, apoptosis, and most serologic endpoints; however, men on low-fat diets experienced significant decreases in serum cholesterol (P = 0.048).

CONCLUSIONS

Findings suggest that flaxseed is safe and associated with biological alterations that may be protective for prostate cancer. Data also further support low-fat diets to manage serum cholesterol.

Changes in biomarkers of estrogen receptor and growth factor signaling pathways in MCF-7 tumors after short- and long-term treatment with soy and flaxseed

Previously we have shown that MCF-7 human breast tumor growth is stimulated after prolonged treatment with dietary soy protein isolate (SPI). However, the effects are attenuated when SPI is combined with flaxseed (FS). This study determined the changes that occur in tumor growth biomarkers, after both short- and long-term treatment with SPI, FS or their combination, to help identify signaling pathways potentially involved in SPI-stimulated tumor growth. Ovariectomized mice with established MCF-7 tumors were fed basal diet (control), 20%SPI, 10%FS, or SPI+FS for 2 or 25 weeks. After 2 weeks, there were no differences in tumor size, however, compared with control, SPI-treated tumors had higher IGF-IR and cyclin D1 while FS and SPI+FS-fed mice had lower pMAPK expression. After 25 weeks, SPI-treated tumors were larger, had higher proliferation, ERalpha, cyclin D1, IGF-IR, and pMAPK and lower ERbeta and HER2 levels. When combined with FS, however, the effects on these tumor biomarkers induced by SPI were attenuated. This study demonstrates that SPI and FS differently modulate tumor biomarkers of estrogen and growth factor signaling pathways, after both short- and long-term treatment, which may indicate a role of these pathways in the tumor stimulatory effects of SPI and the tumor inhibitory effects of FS.

Multi-targeted therapy of cancer by omega-3 fatty acids

Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) are essential fatty acids necessary for human health. Currently, the Western diet contains a disproportionally high amount of n-6 PUFAs and low amount of n-3 PUFAs, and the resulting high n-6/n-3 ratio is thought to contribute to cardiovascular disease, inflammation, and cancer. Studies in human populations have linked high consumption of fish or fish oil to reduced risk of colon, prostate, and breast cancer, although other studies failed to find a significant association. Nonetheless, the available epidemiological evidence, combined with the demonstrated effects of n-3 PUFAs on cancer in animal and cell culture models, has motivated the development of clinical interventions using n-3 PUFAs in the prevention and treatment of cancer, as well as for nutritional support of cancer patients to reduce weight loss and modulate the immune system. In this review, we discuss the rationale for using long-chain n-3 PUFAs in cancer prevention and treatment and the challenges that such approaches pose in the design of clinical trials.

Dietary lariciresinol attenuates mammary tumor growth and reduces blood vessel density in human MCF-7 breast cancer xenografts and carcinogen-induced mammary tumors in rats

Lariciresinol is a dietary lignan that accounts for a significant portion of the total phytoestrogen intake from Western foods. Recent epidemiological studies suggest that high dietary intake of lignans and lariciresinol is associated with reduced breast cancer risk. However, no causal relationship between lariciresinol intake and breast cancer development has been established. In this study, we investigated for the first time the effects and possible mechanisms of action of lariciresinol on hormone responsive mammary cancer in vivo in dimethylbenz[a]anthracene induced mammary cancer in rats, and in human MCF-7 breast cancer xenografts in athymic mice. For tumor bearing rats, lariciresinol (3 or 15 mg/kg of body weight) or vehicle was administered p.o. daily for 9 weeks. For E2-maintained ovariectomized athymic mice bearing orthotopic MCF-7 tumors, control diet (AIN-93G) or lariciresinol containing diet (AIN-93G supplemented with 20 or 100 mg of lariciresinol/kg of diet) was administered for 5 weeks. In both models, lariciresinol administration inhibited the tumor growth and tumor angiogenesis. In MCF-7 cells, enterolactone significantly inhibited the E2-stimulated VEGF secretion. Moreover, in MCF-7 xenografts, lariciresinol administration enhanced tumor cell apoptosis and increased estrogen receptor beta expression. Lariciresinol and its further metabolites secoisolariciresinol, enterodiol and enterolactone were found in serum of both rats and athymic mice confirming a similar lignan metabolism pattern as in humans. These findings indicate conceivable importance of dietary lignan lariciresinol in inhibition of breast cancer development.

Do phytoestrogens reduce the risk of breast cancer and breast cancer recurrence? What clinicians need to know

Oestrogen is an important determinant of breast cancer risk. Oestrogen-mimicking plant compounds called phytoestrogens can bind to oestrogen receptors and exert weak oestrogenic effects. Despite this activity, epidemiological studies suggest that the incidence of breast cancer is lower in countries where the intake of phytoestrogens is high, implying that these compounds may reduce breast cancer risk, and possibly have an impact on survival. Isoflavones and lignans are the most common phytoestrogens in the diet. In this article, we present findings from human observational and intervention studies related to both isoflavone and lignan exposure and breast cancer risk and survival. In addition, the clinical implications of these findings are examined in the light of a growing dietary supplement market. An increasing number of breast cancer patients seek to take supplements together with their standard treatment in the hope that these will either prevent recurrence or treat their menopausal symptoms. Observational studies suggest a protective effect of isoflavones on breast cancer risk and the case may be similar for increasing lignan consumption although evidence so far is inconsistent. In contrast, short-term intervention studies suggest a possible stimulatory effect on breast tissue raising concerns of possible adverse effects in breast cancer patients. However, owing to the dearth of human studies investigating effects on breast cancer recurrence and survival the role of phytoestrogens remains unclear. So far, not enough clear evidence exists on which to base guidelines for clinical use, although raising patient awareness of the uncertain effect of phytoestrogens is recommended.

Lignan-rich sesame seed negates the tumor-inhibitory effect of tamoxifen but maintains bone health in a postmenopausal athymic mouse model with estrogen-responsive breast tumors

OBJECTIVE

Flaxseed, the richest source of mammalian lignan precursors, enhances the tumor growth-inhibitory effect of tamoxifen while exerting no adverse effects on other estrogen-responsive tissues such as bone. Ingestion of sesame seed produces mammalian lignans comparable with flaxseed, but its anticancer potential is unknown. This study determined the interactive effects of sesame seed and tamoxifen on established MCF-7 tumor growth and bone health in ovariectomized athymic mice simulating a postmenopausal condition.

DESIGN

Mice with established MCF-7 tumors were treated for 8 weeks with (1) basal diet (negative control), (2) 10% sesame seed, (3) basal diet + tamoxifen implant, (4) 10% sesame seed + tamoxifen implant, or (5) basal diet + estrogen implant (positive control). Weekly palpable tumor size, final tumor weight, cell proliferation, and apoptosis were measured. Bone mineral content, bone mineral density, and biomechanical strength testing were performed on the femur and lumbar vertebrae.

RESULTS

Sesame seed induced regression of established tumor size similar to the negative control but tended to negate the tumor-inhibitory effect of tamoxifen, in part by reducing apoptosis. Sesame seed combined with tamoxifen induced higher bone mineral content, bone mineral density, and biomechanical strength in the femur and lumbar vertebrae than either treatment alone. A significant positive relationship was found between final tumor weight and bone strength parameters.

CONCLUSIONS

Sesame seed is not protective and negatively interferes with tamoxifen in inducing regression of established MCF-7 tumor size but beneficially interacts with tamoxifen on bone in ovariectomized athymic mice.

Role of dietary lignans in the reduction of breast cancer risk

Lignans are a large group of fiber-associated phenolic compounds widely distributed in edible plants. Some of the ingested plant lignans are converted by intestinal microbiota to enterolignans, enterodiol (END) and enterolactone (ENL), the latter of which has been thought to be the major biologically active lignan, and suggested to be associated with low risk of breast cancer. In line with this, administration of plant lignans which are further metabolized to ENL, or ENL as such, have been shown to inhibit or delay the growth of experimental mammary cancer. The mechanism of anticarcinogenic action of ENL is not yet fully understood, but there is intriguing evidence for ENL as a modulator of estrogen signaling. These findings have generated interest in the use of lignans as components of breast cancer risk reducing functional foods. Identification of target groups, who would benefit most, is of pivotal importance. Therefore, further identification and validation of relevant biomarkers, which can be used as indicators of lignan or ENL action and breast cancer risk reduction at different stages of the disease, are of importance.

Dietary Flaxseed Interaction With Tamoxifen Induced Tumor Regression in Athymic Mice With MCF-7 Xenografts by Downregulating the Expression of Estrogen Related Gene Products and Signal Transduction Pathways

Our previous short-term study has shown that 10% flaxseed (FS) inhibits the growth of human estrogen dependent estrogen receptor positive breast tumors (MCF-7) xenografts in ovariectomized (OVX) athymic mice and enhances the tumor inhibitory effect of tamoxifen (TAM). This study determined the long-term effect of 5% and 10% FS, with or without TAM, on the growth of MCF-7 xenografts in athymic mice and the potential mechanisms of actions. OVX mice with established MCF-7 tumors were treated with basal diet (control), 5% FS (5FS), 10% FS (10FS), and TAM (5 mg/pellet, 60-day release), alone or in combination, for 16 wk without estrogen supplementation. Tumor growth was monitored weekly. At sacrifice, the tumors were analyzed by immunohistochemistry for cell proliferation, apoptosis, and expression of estrogen-related genes and signal transduction pathways. Both 5FS and 10FS regressed the pretreatment tumor size by over 90% similar to control. TAM initially regressed the tumors but then induced a regrowth; thus, only a final 6% reduction from pretreatment tumor size was achieved, which was attenuated by combining TAM with 10FS but not with 5FS. TAM combined with 10FS regressed tumors to 55% of pretreatment tumor size due to decreased cell proliferation and increased apoptosis. The expressions of cyclin D1, estrogen receptor alpha, human epidermal growth factor receptor 2, and insulin-like growth factor I receptor in the TAM group were significantly reduced when TAM was combined with 5FS or 10FS. In conclusion, after long-term treatment, FS did not stimulate tumor growth and combined with TAM, regressed tumor size in part due to downregulation of the expression of estrogen-related gene products and signal transduction pathways.

Can the combination of flaxseed and its lignans with soy and its isoflavones reduce the growth stimulatory effect of soy and its isoflavones on established breast cancer?

Consumption of phytoestrogen (PE)-rich foods (i. e., soy and flaxseed (FS)) is increasing because of their suggested health benefits. However, recent studies raise concern over the safety of soy and its isoflavones, particularly genistein (GEN), for postmenopausal breast cancer (BC), due to their potential stimulatory effects on human breast tissue and on the growth of existing tumors in rodents. FS, rich in PE lignans, which is metabolized to the mammalian lignans enterolactone (ENL) and enterodiol (END), has consistently been shown to have tumor inhibitory effects in a human clinical trial as well as rodent BC models. Using the preclinical athymic mouse postmenopausal BC model, combining FS with soy protein or GEN with END and ENL, was found to negate the tumor stimulatory effects of soy protein or GEN alone. The mechanism may be related to the modulation of estrogen receptor and MAPK signaling pathways. If these studies can be confirmed in clinical trials, then consumption of combined soy and FS, or their PEs, may reduce the tumor growth stimulatory effect of soy or GEN. This may indicate that if soy is consumed with lignan-rich foods, it may continue to induce its other beneficial health effects, without inducing adverse effect on postmenopausal BC.

Flaxseed and its lignans inhibit estradiol-induced growth, angiogenesis, and secretion of vascular endothelial growth factor in human breast cancer xenografts in vivo

PURPOSE

Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis, which is crucial in cancer progression. We have previously shown that estradiol (E2) increases VEGF in breast cancer. Phytoestrogens are potential compounds in breast cancer prevention and treatment by poorly understood mechanisms. The main phytoestrogens in Western diet are lignans, and flaxseed is a rich source of the mammalian lignans enterodiol and enterolactone.

EXPERIMENTAL DESIGN

In the present study, ovariectomized mice were treated with continuous release of E2. MCF-7 tumors were established and mice were fed with basal diet or 10% flaxseed, and two groups that were fed basal diet received daily injections with enterodiol or enterolactone (15 mg/kg body weight).

RESULTS

We show that flaxseed, enterodiol, and enterolactone counteracted E2-induced growth and angiogenesis in solid tumors. Extracellular VEGF in vivo, sampled using microdialysis, in all intervention groups was significantly decreased compared with tumors in the basal diet group. Our in vivo findings were confirmed in vitro. By adding enterodiol or enterolactone, E2-induced VEGF secretion in MCF-7 cells decreased significantly without agonistic effects. The increased VEGF secretion by E2 in MCF-7 cells increased the expression of VEGF receptor-2 in umbilical vein endothelial cells, suggesting a proangiogenic effect by E2 by two different mechanisms, both of which were inhibited by the addition of lignans.

CONCLUSIONS

Our results suggest that flaxseed and its lignans have potent antiestrogenic effects on estrogen receptor-positive breast cancer and may prove to be beneficial in breast cancer prevention strategies in the future.