Estimated enterolignans, lignan-rich foods, and fibre in relation to survival after postmenopausal breast cancer

Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies

BACKGROUND

Phytonutrient intakes may improve outcomes following breast cancer, but the impact of postdiagnosis introduction vs established prediagnostic exposure as well as optimum doses has not been established. Evidence from observational studies for key exposures was evaluated, including dosage and intake time frames.

METHODS

MEDLINE, EMBASE, CINAHL, Cochrane Library, ClinicalTrials.gov, and the ISRCTN registry were searched for prospective and retrospective observational studies investigating the impact of soybean, lignans, cruciferous (cabbage-family) vegetables, green tea, or their phytonutrients on breast cancer survival outcomes. A random-effects model was used to calculate summary hazard ratios (HRs) and 95% confidence intervals (CIs). Nonlinear dose-response analyses were conducted using restricted cubic splines.

RESULTS

Thirty-two articles were included. Soy isoflavones were associated with a 26% reduced risk of recurrence (HR = 0.74, 95% CI = 0.60 to 0.92), particularly among postmenopausal (HR = 0.72, 95% CI = 0.55 to 0.94) and estrogen receptor-positive survivors (HR = 0.82, 95% CI = 0.70 to 0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20 to 40 mg/day. Soy protein and products were inversely associated with cancer-specific mortality for estrogen receptor-positive disease (HR = 0.75, 95% CI = 0.60 to 0.92). An inverse association was observed for serum or plasma enterolactone, measured prediagnosis and early postdiagnosis, with cancer-specific mortality (HR = 0.72, 95% CI = 0.58 to 0.90) and all-cause mortality (HR = 0.69, 95% CI = 0.57 to 0.83). No effects were observed for cruciferous vegetables. There was a 44% reduced risk of recurrence with prediagnostic green tea for stage I and II breast cancer (HR = 0.56, 95% CI = 0.38 to 0.83).

CONCLUSIONS

Soy, enterolactone, and green tea demonstrated significant risk reductions in outcomes following breast cancer. Evidence is needed regarding the impact of postdiagnostic introduction or substantial increase of these exposures.

Availability of bioactive flax lignan from foods and supplements

Hyperlipidemia, high levels of blood lipids including cholesterol and triglycerides, is a major risk factor for cardiovascular disease. Traditional treatments of hyperlipidemia often include lifestyle changes and pharmacotherapy. Recently, flaxseed has been approved as a nutrient that lowers blood lipids. Several metabolites of flaxseed lignan secoisolariciresinol diglucoside (SDG), have been identified that reduce blood lipids. SDG is present in flaxseed hull as an ester-linked copolymer with 3-hydroxy-3-methylglutaric acid (HMGA). However, purification processes involved in hydrolysis of the copolymer and enriching SDG are often expensive. The natural copolymer of SDG with HMGA (SDG polymer) is a source of bioactive compounds useful in prophylaxis of hypercholesterolemia. After consumption of the lignan copolymer, SDG and HMGA are released in the stomach and small intestines. SDG is metabolized to secoisolariciresinol, enterolactone and enterodiol, the bioactive forms of mammalian lignans. These metabolites are then distributed throughout the body where they accumulate in the liver, kidney, skin, other tissues, and organs. Successively, these metabolites reduce blood lipids including cholesterol, triglycerides, low density lipoprotein cholesterol, and lipid peroxidation products. In this review, the metabolism and efficacies of flaxseed-derived enriched SDG and SDG polymer will be discussed.

Dietary Factors and Breast Cancer Prognosis among Breast Cancer Survivors: A Systematic Review and Meta-Analysis of Cohort Studies

Simple Summary

While most systematic reviews have focused on the association between dietary factors and breast cancer incidence, this current study focuses on the association between comprehensive dietary factors and breast cancer prognosis among breast cancer survivors by systematic review and meta-analysis. We reviewed a total of 63 cohort studies to assess the association between dietary factors and breast cancer prognosis by subgroup analysis with prediagnostic or postdiagnostic dietary intake, menopausal status, and dietary or supplementary micronutrient intake. We found that unhealthy dietary patterns, including the intake of beer and saturated fat, exacerbated the risk of breast cancer prognosis; however, the supplementation of most vitamins was desirable for breast cancer prognosis. Therefore, this study’s systematic review and meta-analysis provide useful dietary information for the development of dietary guidelines/recommendations to improve prognosis among breast cancer survivors.

Abstract

Few studies have summarized the association between dietary factors and breast cancer (BC) prognosis among breast cancer survivors (BCS). Therefore, we carried out a systematic review and meta-analysis to determine the associations between dietary factors and BC prognosis among BCS. We performed a literature search in PubMed and Embase to investigate the association between dietary factors and BC prognosis. We applied a random-effects model to compute the hazard ratio/relative risk and their 95% confidence intervals and heterogeneity (Higgins I²) and to generate forest plots using STATA. Among the 2279 papers identified, 63 cohort studies were included in the systematic review and meta-analysis. Our main finding was that higher consumption of beer and saturated fat negatively affected BC prognosis. However, the intake of lignans, fiber, multivitamins, and antioxidants was negatively associated with the risk of mortality. Furthermore, we performed subgroup analyses by menopausal status and dietary or supplementary micronutrient intake. Most trends were similar to the main findings; in particular, the vitamin C, vitamin D, and vitamin E supplements decreased the risk of mortality. This study’s current systematic review and meta-analysis provide comprehensive dietary information for the development of dietary guidelines/recommendations to improve prognosis among BCS.

The Potential Effects of Phytoestrogens: The Role in Neuroprotection

Phytoestrogens are naturally occurring non-steroidal phenolic plant compounds. Their structure is similar to 17-β-estradiol, the main female sex hormone. This review offers a concise summary of the current literature on several potential health benefits of phytoestrogens, mainly their neuroprotective effect. Phytoestrogens lower the risk of menopausal symptoms and osteoporosis, as well as cardiovascular disease. They also reduce the risk of brain disease. The effects of phytoestrogens and their derivatives on cancer are mainly due to the inhibition of estrogen synthesis and metabolism, leading to antiangiogenic, antimetastatic, and epigenetic effects. The brain controls the secretion of estrogen (hypothalamus-pituitary-gonads axis). However, it has not been unequivocally established whether estrogen therapy has a neuroprotective effect on brain function. The neuroprotective effects of phytoestrogens seem to be related to both their antioxidant properties and interaction with the estrogen receptor. The possible effects of phytoestrogens on the thyroid cause some concern; nevertheless, generally, no serious side effects have been reported, and these compounds can be recommended as health-promoting food components or supplements.

Dietary phytoestrogens and biomarkers of their intake in relation to cancer survival and recurrence: a comprehensive systematic review with meta-analysis

CONTEXT

Recent studies have outlined the potential role of dietary factors in patients who have survived cancer.

OBJECTIVE

The aim of this study was to summarize the evidence of the relation between dietary intake of phytoestrogens and their blood biomarkers and, overall, cancer-specific mortality and recurrence in patients with cancer.

DATA SOURCES

A systematic search of PubMed, EMBASE, and Web of Science databases of studies published up to September 2019 was performed. Databases were searched for prospective and retrospective cohort studies reporting on dietary phytoestrogen intake and/or blood biomarkers and the outcomes investigated.

DATA EXTRACTION

Data were extracted from each identified study using a standardized form.

DATA ANALYSIS

Twenty-eight articles on breast, lung, prostate, and colorectal cancer, and glioma were included for systematic review. Given the availability of studies, a quantitative meta-analysis was performed solely for breast cancer outcomes. A significant inverse association among higher dietary isoflavone intake, higher serum/plasma enterolactone concentrations, and overall mortality and cancer recurrence was found. Among other cancer types, 2 studies reported that higher serum enterolactone and higher intake of lignans were associated with cancer-specific survival for colorectal cancer and glioma, respectively.

CONCLUSIONS

Dietary phytoestrogens may play a role in survival from breast cancer ; evidence regarding other cancers is too limited to draw any conclusions.

Lignans intake and enterolactone concentration and prognosis of breast cancer: a systematic review and meta-analysis

Background: Some literature has studied the relationship between lignans intake and its metabolite, enterolactone, and breast cancer survival, but the results are far from consistent and conclusive. Therefore, we conducted a systematic review and meta-analysis in this situation.

Methods: From its inception to August 2020, we conducted a comprehensive search of PubMed, Embase, Web of Science, and Cochrane Library databases. This study reported the correlation between lignans intake and serum enterolactone concentrations and prognosis of breast carcinoma. The total hazard ratios (HRs) and 95% confidence interval (95% CI) were estimated, comparing the highest versus the lowest category of lignans intake and serum enterolactone concentrations, using a fixed or random-effects effect model.

Results: A total of 6 articles were included in reporting the all-cause mortality (ACM), breast cancer-specific mortality (BCSM), and recurrence of 2668, 1516, and 474 breast cancer patients in 18053 breast cancer patients. In postmenopausal women with breast cancer, lignans intake or enterolactone concentrations were associated with a reduced risk of all-cause mortality (maximum and minimum) (pooled HR = 0.73, 95% CI, 0.58-0.91), as was the association with breast cancer-specific mortality (maximum and minimum) (pooled HR = 0.72, 95% CI, 0.60, 0.87). Stratified analysis showed that exposure type and diagnosis time might be the sources of heterogeneity. In premenopausal women, the relationship seemed to be the opposite, showing an increased risk of all-cause mortality (maximum and minimum) in breast cancer patients (pooled HR = 1.57, 95% CI, 1.11-2.23). No significant association was found between lignans intake or enterolactone concentrations and breast cancer recurrence (pooled HR = 0.91, 95% CI, 0.69, 1.20).

Conclusion: This study provides limited evidence that lignans intake and higher serum enterolactone concentrations in postmenopausal women are beneficial to breast cancer patients' prognosis. In premenopausal women, however, the relationship may be reversed.

Dietary Fiber and Survival in Women with Breast Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies

We aimed to investigate the association of dietary fiber consumption with mortality risk in women with breast cancer. A systematic search was undertaken in PubMed, Scopus, and ISI Web of Science till March 2020 to find cohort studies investigating the association of dietary fiber consumption with mortality risk in women with breast cancer. A random-effects model was used to combine study-specific results. The quality of evidence was rated by NutriGrade score. Seven prospective cohort studies with 1,426 cases of all-cause mortality and 679 cases of breast cancer-specific mortality among 11,295 patients with breast cancer were included. The relative risks for the highest compared to the lowest category of dietary fiber consumption were 0.63 (95%CI: 0.52, 0.77; I² = 0%, n = 5) for all-cause mortality, and 0.72 (95%CI: 0.54, 0.96; I² = 0%, n = 5) for breast cancer-specific mortality. There was a strong linear association between fiber intake and all-cause mortality risk. The quality of evidence was rated moderate for all-cause mortality, and low for breast cancer-specific mortality. Higher dietary fiber consumption may improve survival in patients with breast cancer. More research is needed to confirm the present results, considering types of fiber consumed and tumor estrogen receptor status.

Lignans from linseed (Linum usitatissimum L.) and its allied species: Retrospect, introspect and prospect

Lignans are complex diphenolic compounds representing phytoestrogens and occur widely across the plant kingdom. Formed by the coupling of two coniferyl alcohol residues, lignans constitute major plant "specialized metabolites" with exceptional biological attributes that aid in plant defence and provide health benefits in humans by reducing the risk of ailments such as cancer, diabetes etc. Linseed (Linum usitatissimum L.) is one of the richest sources of lignans followed by cereals and legumes. Among the various types of lignans, secoisolariciresinol diglucoside (SDG) is considered as the essential and nutrient rich lignan in linseed. Lignans exhibit established antimitotic, antiviral and anti-tumor properties that contribute to their medicinal value. The present review seeks to provide a holistic view of research in the past and present times revolving around lignans from linseed and its allied species. This review attempts to elucidate sources, structures and functional properties of lignans, along with detailed biosynthetic mechanisms operating in plants. It summarizes various methods for the determination of lignan content in plants. Biotechnological interventions (in planta and in vitro) aimed at enriching lignan content and adoption of integrative approaches that might further enhance lignan content and medicinal and nutraceutical value of Linum spp. have also been discussed.

Impact of lignans in oilseed mix on gut microbiome composition and enterolignan production in younger healthy and premenopausal women: an in vitro pilot study

BACKGROUND

Dietary lignans belong to the group of phytoestrogens together with coumestans, stilbenes and isoflavones, and themselves do not exhibit oestrogen-like properties. Nonetheless, the gut microbiota converts them into enterolignans, which show chemical similarity to the human oestrogen molecule. One of the richest dietary sources of lignans are oilseeds, including flaxseed. The aim of this pilot study was to determine the concentration of the main dietary lignans in an oilseed mix, and explore the gut microbiota-dependent production of enterolignans for oestrogen substitution in young and premenopausal women. The oilseed mix was fermented in a pH-controlled batch culture system inoculated with women's faecal samples. The lignan content and enterolignan production were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and the faecal-derived microbial communities were profiled by 16S rRNA gene-based next-generation sequencing.

RESULTS

In vitro batch culture fermentation of faecal samples inoculated with oilseed mix for 24 h resulted in a substantial increase in enterolactone production in younger women and an increase in enterodiol in the premenopausal group. As for the gut microbiota, different baseline profiles were observed as well as different temporal dynamics, mainly related to Clostridiaceae, and Klebsiella and Collinsella spp.

CONCLUSIONS

Despite the small sample size, our pilot study revealed that lignan-rich oilseeds could strongly influence the faecal microbiota of both younger and premenopausal females, leading to a different enterolignan profile being produced. Further studies in larger cohorts are needed to evaluate the long-term effects of lignan-rich diets on the gut microbiota and find out how enterolactone-producing bacterial species could be increased. Diets rich in lignans could potentially serve as a safe supplement of oestrogen analogues to meet the cellular needs of endogenous oestrogen and deliver numerous health benefits, provided that the premenopausal woman microbiota is capable of converting dietary precursors into enterolignans.

Pre- and post-diagnostic intake of whole grain and dairy products and breast cancer prognosis: the Danish Diet, Cancer and Health cohort

PURPOSE

Fiber rich foods and dairy products have been suggested to be associated with breast cancer prognosis, though existing research is limited and either report on pre- or post-diagnostic dietary intake in relation to breast cancer prognosis. We investigated the associations between intake of whole grain (WG) and dairy products assessed both pre- and post-diagnostically in relation to breast cancer prognosis.

METHODS

A total of 1965 women from the Diet, Cancer and Health cohort who were diagnosed with breast cancer between baseline (1993-1997) and December 2013 were included and followed for a median of 7 years after diagnosis. During follow-up, 309 women experienced breast cancer recurrence and 460 women died, of whom 301 died from breast cancer. Dietary assessment by food frequency questionnaires was obtained up to three times, pre- and post-diagnostic, over a period of 18 years. Cox proportional hazard models were used to estimate hazard ratios.

RESULTS

No associations were observed between pre- or post-diagnostic intake of total WG or total dairy products and breast cancer prognosis. A high pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality (HR 0.76, 95% CI 0.59-0.99), whereas high post-diagnostic intake of rye bread was associated with higher breast cancer-specific mortality (HR 1.29, 95% CI 1.02-1.63). A generally high intake of cheese was associated with a higher recurrence rate.

CONCLUSION

Pre-diagnostic intake of oatmeal/muesli was associated with lower all-cause mortality, and post-diagnostic intake of rye bread was associated with higher breast cancer specific mortality.

Anticancer and antimetastatic potential of enterolactone: Clinical, preclinical and mechanistic perspectives

Currently cancer is the second leading cause of death globally and worldwide incidence and mortality rates of all cancers of males and females are rising tremendously. In spite of advances in chemotherapy and radiation, metastasis and recurrence are considered as the major causes of cancer related deaths. Hence there is a mounting need to develop new therapeutic modalities to treat metastasis and recurrence in cancers. A significant amount of substantiation from epidemiological, clinical and laboratory research highlights the importance of diet and nutrition in cancer chemoprevention. Enterolactone (EL) is a bioactive phenolic metabolite known as a mammalian lignan derived from dietary lignans. Here in we review the reported anti-cancer properties of EL at preclinical as well as clinical level. Several in-vivo and in-vitro studies have provided strong evidence that EL exhibits potent anti-cancer and/or protective properties against different cancers including breast, prostate, colo-rectal, lung, ovarian, endometrial, cervical cancers and hepatocellular carcinoma. Reported laboratory studies indicate a clear role for EL in preventing cancer progression at various stages including cancer cell proliferation, survival, angiogenesis, inflammation and metastasis. In clinical settings, EL has been reported to reduce risk, decrease mortality rate and improve overall survival particularly in breast, prostate, colon, gastric and lung cancer. Further, the in-vitro human cell culture studies provide strong evidence of the anticancer and antimetastatic mechanisms of EL in several cancers. This comprehensive review supports an idea of projecting EL as a promising candidate for developing anticancer drug or adjunct dietary supplements and nutraceuticals.

Dietary fiber intake and mortality in a Mediterranean population: the "Seguimiento Universidad de Navarra" (SUN) project

PURPOSE

To prospectively assess the association of dietary fiber intake (from different dietary sources) with all-cause mortality in a Mediterranean cohort.

METHODS

We assessed 19,703 participants of the SUN (Seguimiento Universidad de Navarra) cohort (mean follow-up: 10.1 years). A validated 136-item FFQ was administered at baseline. We used Cox proportional hazards models adjusted for multiple socio-demographic, anthropometric, lifestyle factors, and prevalent conditions at baseline.

RESULTS

We observed 323 deaths during 198,341 person-years of follow-up. A significantly inverse linear trend in Cox models was observed for the association of total dietary fiber intake and all-cause mortality after adjustment for confounders (p for trend 0.017). Each additional intake of 5 g/1000 kcal of dietary fiber was associated with a 9% relative reduction in all-cause mortality risk (HR 0.91, 95% CI 0.84-0.99). Considering separate dietary sources in separate models, a significant inverse trend was apparent for fiber derived from vegetables (p for trend 0.001), but it was non-significant for fiber derived from fruit, legumes, cereals, or other sources. Soluble fiber was significantly inversely associated with all-cause mortality in the fully adjusted model (p for trend 0.007), and insoluble fiber was marginally significant (p for trend 0.08).

CONCLUSIONS

A higher intake of total dietary fiber, and particularly fiber from vegetables, was related to a reduced all-cause mortality in our Mediterranean cohort. Dietary messages to increase the consumption of dietary patterns rich in fiber-rich foods should be broadly disseminated to decrease the alarming rate of chronic diseases and its derived mortality.

The flaxseed lignan secoisolariciresinol diglucoside decreases local inflammation, suppresses NFκB signaling, and inhibits mammary tumor growth

PURPOSE

Exposure to the polyphenolic plant lignan secoisolariciresinol diglucoside (SDG) and its metabolite enterolactone (ENL) has been associated with reduced breast cancer progression, particularly for estrogen receptor alpha (ERα)-negative disease, and decreased preclinical mammary tumor growth. However, while preclinical studies have established that SDG and ENL affect measures of progression in models of triple-negative breast cancer (TNBC, a subset of ERα-negative disease), the molecular mechanisms underlying these effects remain unclear.

METHODS

C57BL/6 mice were fed a control diet (control, 10% kcal from fat) or control diet + SDG (SDG, 100 mg/kg diet) for 8 weeks, then orthotopically injected with syngeneic E0771 mammary tumor cells (a model of TNBC); tumor growth was monitored for 3 weeks. The role of reduced NF-κB signaling in SDG's anti-tumor effects was explored in vitro via treatment with the bioactive SDG metabolite ENL. In addition to the murine E0771 cells, the in vitro studies utilized MDA-MB-231 and MCF-7 cells, two human cell lines which model the triple-negative and luminal A breast cancer subtypes, respectively.

RESULTS

SDG supplementation in the mice significantly reduced tumor volume and expression of phospho-p65 and NF-κB target genes (P < 0.05). Markers of macrophage infiltration were decreased in the distal-to-tumor mammary fat pad of mice supplemented with SDG relative to control mice (P < 0.05). In vitro, ENL treatment inhibited viability, survival, and NF-κB activity and target gene expression in E0771, MDA-MB-231, and MCF-7 cells (P < 0.05). Overexpression of Rela attenuated ENL's inhibition of E0771 cell viability and survival.

CONCLUSIONS

SDG reduces tumor growth in the E0771 model of TNBC, likely via a mechanism involving inhibition of NF-κB activity. SDG could serve as a practical and effective adjuvant treatment to reduce recurrence, but greater understanding of its effects is needed to inform the development of more targeted recommendations for its use.

Advising Women Undergoing Treatment for Breast Cancer: A Narrative Review

A majority of women undergoing conventional treatment for breast cancer also undertake complementary and integrative approaches. Practitioners knowledgeable about the evidence base behind common integrative approaches can help patients attain improved quality of life, and at times, improved survival. Evidence-based recommendations include the following: a plant-based diet for general health after diagnosis, and carbohydrate restriction for patients with estrogen receptor-positive postmenopausal breast cancer may be prudent. Other dietary recommendations include a 13-h daily overnight fast. Carefully selected patients may choose to fast the day before and the day of chemotherapy to decrease side effects. Specific food recommendations include avoidance or limitation of alcohol, and liberal culinary use of cruciferous vegetables, coffee, green tea, soy, and flaxseed. Promising supplements include diindolylmethane and melatonin. Omega 3 fatty acids may help with bone density in patients on aromatase inhibitors, but may increase chemotherapy resistance. Findings regarding the usefulness of multivitamins, vitamin D, vitamin C, and vitamin E are weak and/or mixed different exercise modalities may have different effects and thus play different roles in breast cancer therapy. Aerobic and resistance training combined during breast cancer chemotherapy may confer a survival benefit, while yoga may improve outcome in lymphedema patients. Current evidence suggests that meditation, yoga, breathing, music therapy, guided imagery, and hypnosis may improve mood and quality of life during breast cancer treatment. Acupuncture is useful for treating side effects of breast cancer therapies, including hot flushes, aromatase inhibitor-induced joint pain, chemotherapy-induced peripheral neuropathy, and vulvodynia. Vaginal moisturizers and vaginal rings supplying low-dose estrogen can be useful in the treatment of symptoms of estrogen-deprivation states caused by breast cancer treatments; such symptoms include vaginal dryness, dyspareunia, and sexual dysfunction. Carbon dioxide laser technology can rejuvenate atrophied vaginal mucosa and relieve dyspareunia, allowing avoidance of estrogen therapy. Tertiary sexual health centers are available for referral.

Impact of dietary patterns and the main food groups on mortality and recurrence in cancer survivors: a systematic review of current epidemiological literature

OBJECTIVE

To determine whether there is an association between dietary patterns/indices and foods from the main food groups (highest vs lowest intakes) prior to or after cancer diagnosis and mortality and cancer recurrence in cancer survivors.

PARTICIPANTS

Survivors of common cancers with a 10-year survival rate of ≥50%: bladder, bowel, breast, cervical, kidney, laryngeal, prostate, testicular, uterine cancer, malignant melanoma and (non-)Hodgkin's lymphoma.

OUTCOME MEASURES

Mortality (overall, cancer-specific, from other causes) and cancer recurrence.

INFORMATION SOURCES

PubMed, Embase and the Cochrane Library were searched from inception to April 2017. Additional studies were identified by searching reference lists. Two authors independently screened titles and abstracts, assessed study quality and extracted the data.

RESULTS

A total of 38 studies were included. The risk of bias was rated low for the included randomised controlled trials (RCTs) and moderate for the cohort studies. The quality of evidence was assessed with the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach and was rated moderate (RCTs), and (very)low (cohort studies). Reducing the amount of fat after diagnosis appears to decrease the risk of breast cancer recurrence. Adherence to a high-quality diet and prudent diet after diagnosis appears to decrease the risk of death from other causes (and overall mortality for high-quality diet) in breast cancer survivors. Adherence to a Western diet, before and after diagnosis, appears to increase the risk of overall mortality and death from other causes among breast cancer survivors. Evidence from studies among other cancer survivors was too limited or could not be identified.

CONCLUSION

For many cancer survivors, there is little evidence to date to indicate that particular dietary behaviours influence outcomes with regard to recurrence and mortality. Notwithstanding, limited evidence suggests that a low-fat diet, a high-quality diet and a prudent diet are beneficial for breast cancer survivors, while a Western diet is detrimental for breast cancer survivors.

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.

Induced Mutagenesis in UGT74S1 Gene Leads to Stable New Flax Lines with Altered Secoisolariciresinol Diglucoside (SDG) Profiles

Flax secoisolariciresinol (SECO) diglucoside (SDG) lignan is an emerging natural product purported to prevent chronic diseases in humans. SECO, the aglycone form of SDG, has shown higher intestinal cell absorption but it is not accumulated naturally in planta. Recently, we have identified and characterized a UDP-glucosyltransferase gene, UGT74S1, that glucosylates SECO into its monoglucoside (SMG) and SDG forms when expressed in yeast. However, whether this gene is unique in controlling SECO glucosylation into SDG in planta is unclear. Here, we report on the use of UGT74S1 in reverse and forward genetics to characterize an ethyl methane sulfonate (EMS) mutagenized flax population from cultivar CDC Bethune and consisting of 1996 M2 families. EMS mutagenesis generated 73 SNP variants causing 79 mutational events in the UGT74S1 exonic regions of 93 M2 families. The mutation frequency in the exonic regions was determined to be one per 28 Kb. Of these mutations, 13 homozygous missense mutations and two homozygous nonsense mutations were observed and all were transmitted into the M3 and M4 generations. Forward genetics screening of the population showed homozygous nonsense mutants completely lacking SDG biosynthesis while the production of SMG was observed only in a subset of the M4 lines. Heterozygous or homozygous M4 missense mutants displayed a wide range of SDG levels, some being greater than those of CDC Bethune. No additional deleterious mutations were detected in these mutant lines using a panel of 10 other genes potentially involved in the lignan biosynthesis. This study provides further evidence that UGT74S1 is unique in controlling SDG formation from SECO and this is the first report of non-transgenic flax germplasm with simultaneous knockout of SDG and presence of SMG in planta.

Phytotherapy and Nutritional Supplements on Breast Cancer

Breast cancer is the most frequent type of nonskin malignancy among women worldwide. In general, conventional cancer treatment options (i.e., surgery, radiotherapy, chemotherapy, biological therapy, and hormone therapy) are not completely effective. Recurrence and other pathologic situations are still an issue in breast cancer patients due to side effects, toxicity of drugs in normal cells, and aggressive behaviour of the tumours. From this point of view, breast cancer therapy and adjuvant methods represent a promising and challenging field for researchers. In the last few years, the use of some types of complementary medicines by women with a history of breast cancer has significantly increased such as phytotherapeutic products and nutritional supplements. Despite this, the use of such approaches in oncologic processes may be problematic and patient's health risks can arise such as interference with the efficacy of standard cancer treatment. The present review gives an overview of the most usual phytotherapeutic products and nutritional supplements with application in breast cancer patients as adjuvant approach. Regardless of the contradictory results of scientific evidence, we demonstrated the need to perform additional investigation, mainly well-designed clinical trials in order to establish correlations and allow for further validated outcomes concerning the efficacy, safety, and clinical evidence-based recommendation of these products.

Enterolactone has stronger effects than enterodiol on ovarian cancer

Background

Ovarian cancer is one of the three leading gynecological malignancies, characterized by insidious growth, highly frequent metastasis, and quick development of drug resistance. As a result, this disease has low 5-year survival rates. Estrogen receptor inhibitors were commonly used for the treatment, but only 7% to 18% of patients respond to anti-estrogen therapies. Therefore, more effective therapies to inhibit estrogen-related tumors are urgently needed. Recently, phytoestrogens, such as lignans with estrogen-like biological activities, have attracted attention for their potential effects in the prevention or treatment of estrogen-related diseases. Enterodiol (END) and enterolactone (ENL) are mammalian lignans, which can reduce the risk of various cancers. However, the effects of END and ENL on ovarian cancer are not adequately documented.

Methods

We used in vitro assays on the ES-2 cell line to evaluate the inhibiting effects of END and ENL on ovarian cancer cell proliferation, invasion and migration ability and in vivo xenograft experiments on nude mice to validate the anticancer effects of END and ENL.

Results

The in vitro assays demonstrated that high-dose END and ENL could obviously inhibit ovarian malignant properties, including cancerous proliferation, invasion, and metastasis. Compared to END, ENL behaved in a better time-dose dependent manner on the cancer cells. The in vivo experiments showed that END (1 mg/kg), ENL (1 mg/kg) and ENL (0.1 mg/kg) suppressed tumor markedly, and there were statistically significant differences between the experimental and control groups in tumor weight and volume. Compared to END, which have serious side effects to the animals at high concentration such as 1 mg/kg, ENL had higher anticancer activities and less side effects in the animals than END at the same concentrations, so it would be a better candidate for drug development.

Conclusion

END and ENL both have potent inhibitory effects on ovarian cancer but ENL possesses a more effective anti-cancer capability and less side effects than END. Findings in this work provide novel insights into ovarian cancer therapeutics with phytoestrogens and encourage their clinical applications.

The potential health effects of dietary phytoestrogens

Phytoestrogens are plant-derived dietary compounds with structural similarity to 17-β-oestradiol (E2), the primary female sex hormone. This structural similarity to E2 enables phytoestrogens to cause (anti)oestrogenic effects by binding to the oestrogen receptors. The aim of the present review is to present a state-of-the-art overview of the potential health effects of dietary phytoestrogens. Various beneficial health effects have been ascribed to phytoestrogens, such as a lowered risk of menopausal symptoms like hot flushes and osteoporosis, lowered risks of cardiovascular disease, obesity, metabolic syndrome and type 2 diabetes, brain function disorders, breast cancer, prostate cancer, bowel cancer and other cancers. In contrast to these beneficial health claims, the (anti)oestrogenic properties of phytoestrogens have also raised concerns since they might act as endocrine disruptors, indicating a potential to cause adverse health effects. The literature overview presented in this paper illustrates that several potential health benefits of phytoestrogens have been reported but that, given the data on potential adverse health effects, the current evidence on these beneficial health effects is not so obvious that they clearly outweigh the possible health risks. Furthermore, the data currently available are not sufficient to support a more refined (semi) quantitative risk-benefit analysis. This implies that a definite conclusion on possible beneficial health effects of phytoestrogens cannot be made.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Pre-diagnosis diet and survival after a diagnosis of ovarian cancer

Background:

The relationship between diet and survival after ovarian cancer diagnosis is unclear as a result of a limited number of studies and inconsistent findings.

Methods:

We examined the association between pre-diagnostic diet and overall survival in a population-based cohort (n=811) of Australian women diagnosed with invasive epithelial ovarian cancer between 2002 and 2005. Diet was measured by validated food frequency questionnaire. Deaths were ascertained up to 31 August 2014 via medical record review and Australian National Death Index linkage. We conducted Cox proportional hazards regression analysis, controlling for diagnosis age, tumour stage, grade and subtype, residual disease, smoking status, body mass index, physical activity, marital status, and energy intake.

Results:

We observed improved survival with highest compared with lowest quartile of fibre intake (hazard ratio (HR)=0.69, 95% CI: 0.53–0.90, P-trend=0.002). There was a suggestion of better survival for women with highest compared with lowest intake category of green leafy vegetables (HR=0.79, 95% CI: 0.62–0.99), fish (HR=0.74, 95% CI: 0.57–0.95), poly- to mono-unsaturated fat ratio (HR=0.76, 95% CI: 0.59–0.98), and worse survival with higher glycaemic index (HR=1.28, 95% CI: 1.01–1.65, P-trend=0.03).

Conclusions:

The associations we observed between healthy components of diet pre-diagnosis and ovarian cancer survival raise the possibility that dietary choices after diagnosis may improve survival.

Consumption of vegetables and fruits and breast cancer survival: a systematic review and meta-analysis

We aimed to conduct a meta-analysis investigating the association between consumption of vegetables and fruits and breast cancer survival. A comprehensive search of the PubMed and EMBASE was performed from the inception to September 30, 2016. The summary hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using a random effects model. Ten studies, with a total of 31,210 breast cancer cases, were included in the meta-analysis. The summary HRs (95% CIs) of overall survival (highest vs. lowest) were 1.08 (0.88–1.33; I² = 41.1%) for pre-diagnostic intake of vegetables and fruits combined, 0.96 (0.71–1.30; I² = 48.4%) for vegetables alone, and 0.83 (0.67–1.02; I² = 0) for fruit alone. No significant risk associations of overall survival were found for post-diagnostic intake of vegetables and fruits. Line dose-response analyses indicated the likely results for both pre- and post- diagnostic dietary intake. No significant association was found between intake of vegetables and fruits and breast cancer-specific mortality. In addition, intake of cruciferous vegetables was not associated with death from breast cancer. Our findings indicated a borderline inverse association between pre-diagnostic intake of fruit and overall survival of breast cancer, whereas intake of vegetables was not associated with survival.

Fruit and vegetable intake and breast cancer prognosis: a meta-analysis of prospective cohort studies

The effect of fruit and vegetable intake on breast cancer prognosis is controversial. Thus, a meta-analysis was carried out to explore their associations. A comprehensive search was conducted in PubMed, Web of Science, OVID, ProQuest and Chinese databases from inception to April 2016. The summary hazard ratios (HR) and 95 % CI were estimated using a random effects model if substantial heterogeneity existed and using a fixed effects model if not. Subgroup analyses and sensitivity analyses were also performed. In total, twelve studies comprising 41 185 participants were included in the meta-analysis. Comparing the highest with the lowest, the summary HR for all-cause mortality were 1·01 (95 % CI 0·72, 1·42) for fruits and vegetables combined, 0·96 (95 % CI 0·83, 1·12) for total vegetable intake, 0·99 (95 % CI 0·89, 1·11) for cruciferous vegetable intake and 0·88 (95 % CI 0·74, 1·05) for fruit intake; those for breast cancer-specific mortality were 1·05 (95 % CI 0·77, 1·43) for total vegetable intake and 0·94 (95 % CI 0·69, 1·26) for fruit intake; and those for breast cancer recurrence were 0·89 (95 % CI 0·53, 1·50) for total vegetable intake and 0·98 (95 % CI 0·76, 1·26) for cruciferous vegetable intake. This meta-analysis found no significant associations between fruit and vegetable intake and breast cancer prognosis.

UGT74S1 is the key player in controlling secoisolariciresinol diglucoside (SDG) formation in flax

BACKGROUND

Flax lignan, commonly known as secoisolariciresinol (SECO) diglucoside (SDG), has recently been reported with health-promoting activities, including its positive impact in metabolic diseases. However, not much was reported on the biosynthesis of SDG and its monoglucoside (SMG) until lately. Flax UGT74S1 was recently reported to sequentially glucosylate SECO into SMG and SDG in vitro. However, whether this gene is the only UGT achieving SECO glucosylation in flax was not known.

RESULTS

Flax genome-wide mining for UGTs was performed. Phylogenetic and gene duplication analyses, heterologous gene expression and enzyme assays were conducted to identify family members closely related to UGT74S1 and to establish their roles in SECO glucosylation. A total of 299 different UGTs were identified, of which 241 (81%) were duplicated. Flax UGTs diverged 2.4-153.6 MYA and 71% were found to be under purifying selection pressure. UGT74S1, a single copy gene located on chromosome 7, displayed no evidence of duplication and was deemed to be under positive selection pressure. The phylogenetic analysis identified four main clusters where cluster 4, which included UGT74S1, was the most diverse. The duplicated UGT74S4 and UGT74S3, located on chromosomes 8 and 14, respectively, were the most closely related to UGT74S1 and were differentially expressed in different tissues. Heterologous expression levels of UGT74S1, UGT74S4 and UGT74S3 proteins were similar but UGT74S4 and UGT74S3 glucosylation activity towards SECO was seven fold less than UGT74S1. In addition, they both failed to produce SDG, suggesting neofunctionalization following their divergence from UGT74S1.

CONCLUSIONS

We showed that UGT74S1 is closely related to two duplicated genes, UGT74S4 and UGT74S3 which, unlike UGT74S1, failed to glucosylate SMG into SDG. The study suggests that UGT74S1 may be the key player in controlling SECO glucosylation into SDG in flax although its closely related genes may also contribute to a minor extent in supplying the SMG precursor to UGT74S1.

Phytochemicals and potential health effects of Sambucus williamsii Hance (Jiegumu)

Sambucus williamsii Hance (Jiegumu) is traditionally used in Chinese medicine to treat bone and joint diseases. The major phytochemicals in S. williamsii are lignans, terpenoids, and phenolic acids, together with trace amounts of essential oils, minerals, amino acids, and natural pigments. In this review, a database search for studies published from 1990 to November 2015 was conducted using PubMed, the China Academic Journals Full-Text Database, and Google Scholar with the keywords “Sambucus williamsii Hance”, “Sambucus williamsii”, “Sambucuswilliamsii + clinic”, “Sambucuswilliamsii + biology”, “Sambucuswilliamsii + chemicals”, and “Jiegumu”, which covered chemical studies, cell culture studies, animal experiments, and clinical studies. This article reviewed the compounds isolated from S. williamsii that may reduce the risk of cancer, and exert antifungal, antioxidant, anti-inflammatory, bone fracture healing, and antiosteoporotic effects.

Essences in metabolic engineering of lignan biosynthesis

Lignans are structurally and functionally diverse phytochemicals biosynthesized in diverse plant species and have received wide attentions as leading compounds of novel drugs for tumor treatment and healthy diets to reduce of the risks of lifestyle-related non-communicable diseases. However, the lineage-specific distribution and the low-amount of production in natural plants, some of which are endangered species, hinder the efficient and stable production of beneficial lignans. Accordingly, the development of new procedures for lignan production is of keen interest. Recent marked advances in the molecular and functional characterization of lignan biosynthetic enzymes and endogenous and exogenous factors for lignan biosynthesis have suggested new methods for the metabolic engineering of lignan biosynthesis cascades leading to the efficient, sustainable, and stable lignan production in plants, including plant cell/organ cultures. Optimization of light conditions, utilization of a wide range of elicitor treatments, and construction of transiently gene-transfected or transgenic lignan-biosynthesizing plants are mainly being attempted. This review will present the basic and latest knowledge regarding metabolic engineering of lignans based on their biosynthetic pathways and biological activities, and the perspectives in lignan production via metabolic engineering.

Enterolignan-producing phenotypes are associated with increased gut microbial diversity and altered composition in premenopausal women in the United States

BACKGROUND

Lignans in plant foods are metabolized by gut bacteria to the enterolignans, enterodiol (END) and enterolactone (ENL). Enterolignans have biologic activities important to the prevention of cancer and chronic diseases. We examined the composition of the gut microbial community (GMC) as a contributor to human enterolignan exposure.

METHODS

We evaluated the association between the GMC in stool, urinary enterolignan excretion, and diet from a 3-day food record in 115 premenopausal (ages 40-45 years) women in the United States. Urinary enterolignans were measured using gas chromatography-mass spectroscopy. The GMC was evaluated using 454 pyrosequencing of the 16S rRNA gene. Sequences were aligned in SILVA (www.arb-silva.de). Operational taxonomic units were identified at 97% sequence similarity. Taxonomic classification was performed and alpha and beta diversity in relationship to ENL production were assessed. Multivariate analysis and regression were used to model the association between enterolignan excretion and the GMC. Bacteria associated with ENL production were identified using univariate analysis and ridge regression.

RESULTS

After adjusting for dietary fiber intake and adiposity, we found a significant positive association between ENL excretion and either the GMC (P = 0.0007), or the diversity of the GMC (P = 0.01). The GMC associated with high ENL production was distinct (UNIFRAC, P < 0.003, MRPP) and enriched in Moryella spp., Acetanaerobacterium spp., Fastidiosipila spp., and Streptobacillus spp.

CONCLUSION

Diversity and composition of the GMC are associated with increased human exposure to enterolignans.

IMPACT

Differences in gut microbial diversity and composition explain variation in gut metabolic processes that affect environmental exposures and influence human health. Cancer Epidemiol Biomarkers Prev; 24(3); 546-54. ©2014 AACR.

Histidine 352 (His352) and tryptophan 355 (Trp355) are essential for flax UGT74S1 glucosylation activity toward secoisolariciresinol

Flax secoisolariciresinol diglucoside (SDG) lignan is a natural phytoestrogen for which a positive role in metabolic diseases is emerging. Until recently however, much less was known about SDG and its monoglucoside (SMG) biosynthesis. Lately, flax UGT74S1 was identified and characterized as an enzyme sequentially glucosylating secoisolariciresinol (SECO) into SMG and SDG when expressed in yeast. However, the amino acids critical for UGT74S1 glucosyltransferase activity were unknown. A 3D structural modeling and docking, site-directed mutagenesis of five amino acids in the plant secondary product glycosyltransferase (PSPG) motif, and enzyme assays were conducted. UGT74S1 appeared to be structurally similar to the Arabidopsis thaliana UGT72B1 model. The ligand docking predicted Ser357 and Trp355 as binding to the phosphate and hydroxyl groups of UDP-glucose, whereas Cys335, Gln337 and Trp355 were predicted to bind the 7-OH, 2-OCH3 and 17-OCH3 of SECO. Site-directed mutagenesis of Cys335, Gln337, His352, Trp355 and Ser357, and enzyme assays revealed an alteration of these binding sites and a significant reduction of UGT74S1 glucosyltransferase catalytic activity towards SECO and UDP-glucose in all mutants. A complete abolition of UGT74S1 activity was observed when Trp355 was substituted to Ala355 and Gly355 or when changing His352 to Asp352, and an altered metabolite profile was observed in Cys335Ala, Gln337Ala, and Ser357Ala mutants. This study provided for the first time evidence that Trp355 and His352 are critical for UGT74S1's glucosylation activity toward SECO and suggested the possibility for SMG production in vitro.

Association between dietary fiber and lower risk of all-cause mortality: a meta-analysis of cohort studies

Although in vitro and in vivo experiments have suggested that dietary fiber might have beneficial effects on health, results on the association between fiber intake and all-cause mortality in epidemiologic studies have been inconsistent. Therefore, we conducted a meta-analysis of prospective cohort studies to quantitatively assess this association. Pertinent studies were identified by searching articles in PubMed and Web of Knowledge through May 2014 and reviewing the reference lists of the retrieved articles. Study-specific risk estimates were combined using random-effects models. Seventeen prospective studies (1997-2014) that had a total of 67,260 deaths and 982,411 cohort members were included. When comparing persons with dietary fiber intakes in the top tertile with persons whose intakes were in the bottom tertile, we found a statistically significant inverse association between fiber intake and all-cause mortality, with an overall relative risk of 0.84 (95% confidence interval: 0.80, 0.87; I(2) = 41.2%). There was a 10% reduction in risk for per each 10-g/day increase in fiber intake (relative risk = 0.90; 95% confidence interval: 0.86, 0.94; I(2) = 77.2%). The combined estimate was robust across subgroup and sensitivity analyses. No publication bias was detected. A higher dietary fiber intake was associated with a reduced risk of death. These findings suggest that fiber intake may offer a potential public health benefit in reducing all-cause mortality.

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.

Identification and functional characterization of a flax UDP-glycosyltransferase glucosylating secoisolariciresinol (SECO) into secoisolariciresinol monoglucoside (SMG) and diglucoside (SDG)

BACKGROUND

Lignans are a class of diphenolic nonsteroidal phytoestrogens often found glycosylated in planta. Flax seeds are a rich source of secoisolariciresinol diglucoside (SDG) lignans. Glycosylation is a process by which a glycosyl group is covalently attached to an aglycone substrate and is catalyzed by uridine diphosphate glycosyltransferases (UGTs). Until now, very little information was available on UGT genes that may play a role in flax SDG biosynthesis. Here we report on the identification, structural and functional characterization of 5 putative UGTs potentially involved in secoisolariciresinol (SECO) glucosylation in flax.

RESULTS

Five UGT genes belonging to the glycosyltransferases' family 1 (EC 2.4.x.y) were cloned and characterized. They fall under four UGT families corresponding to five sub-families referred to as UGT74S1, UGT74T1, UGT89B3, UGT94H1, UGT712B1 that all display the characteristic plant secondary product glycosyltransferase (PSPG) conserved motif. However, diversity was observed within this 44 amino acid sequence, especially in the two peptide sequences WAPQV and HCGWNS known to play a key role in the recognition and binding of diverse aglycone substrates and in the sugar donor specificity. In developing flax seeds, UGT74S1 and UGT94H1 showed a coordinated gene expression with that of pinoresinol-lariciresinol reductase (PLR) and their gene expression patterns correlated with SDG biosynthesis. Enzyme assays of the five heterologously expressed UGTs identified UGT74S1 as the only one using SECO as substrate, forming SECO monoglucoside (SMG) and then SDG in a sequential manner.

CONCLUSION

We have cloned and characterized five flax UGTs and provided evidence that UGT74S1 uses SECO as substrate to form SDG in vitro. This study allowed us to propose a model for the missing step in SDG lignan biosynthesis.

Enterolactone concentrations and prognosis after postmenopausal breast cancer: assessment of effect modification and meta-analysis

We previously reported that high concentrations of enterolactone, a lignan metabolite, are associated with lower mortality in 1,140 breast cancer patients from Germany. Using an extended set of 2,182 patients aged 50-74 years at diagnosis (2001-2005) and prospectively followed up until 2009, we investigated whether the association with mortality differs by lifestyle factors and tumor characteristics. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using multivariable Cox regression. Potential differential effects by tumor characteristics and lifestyle factors were assessed and a meta-analysis of five studies addressing lignan exposure and breast cancer prognosis was performed to summarize evidence. Median enterolactone concentrations were 17.4 (± 30.5 standard deviation) and 22.9 nmol L(-1) (± 44.8), respectively, for 269 deceased and 1,913 patients still alive. High enterolactone concentrations were significantly associated with lower all-cause mortality (per 10 nmol L(-1) : HR 0.94, 95% CI 0.90-0.98), breast cancer-specific mortality (HR 0.94, 0.89-0.99), and distant disease-free survival (HR 0.94, 0.90-0.98). Associations were found for stage 0-IIIA but not for stage IIIB-IV disease (p(het) = 0.01) and were stronger in patients with BMI <25 kg m(-2) than those with BMI ≥ 25 (p(het) = 0.04). In patients with healthy lifestyle (BMI <25, nonsmoker, physically active), the inverse association with all-cause mortality was still apparent (HR 0.92, 0.85-0.99). The meta-analysis yielded significant associations both for all-cause (HR 0.57, 0.42-0.78) and breast cancer-specific mortality (HR 0.54, 0.39-0.75). Our findings show that high lignan exposure is associated with reduced mortality in breast cancer patients. The inverse association observed in this study cannot be entirely explained by a healthy lifestyle.

Recent advances in the metabolic engineering of lignan biosynthesis pathways for the production of transgenic plant-based foods and supplements

Plant physiological, epidemiological, and food science studies have shed light on lignans as healthy diets for the reduction of the risk of lifestyle-related noncommunicable diseases and, thus, the demand for lignans has been rapidly increasing. However, the low efficiency and instability of lignan production via extraction from plant resources remain to be resolved, indicating the requirement for the development of new procedures for lignan production. The metabolic engineering of lignan-biosynthesizing plants is expected to be most promising for efficient, sustainable, and stable lignan production. This is supported by the recent verification of biosynthetic pathways of major dietary lignans and the exploration of lignan production via metabolic engineering using transiently gene-transfected or transgenic plants. The aim of this review is to present an overview of the biosynthetic pathways, biological activities, and metabolic engineering of lignans and also perspectives in metabolic engineering-based lignan production using transgenic plants for practical application.

Herbal preparations for the menopause: beyond isoflavones and black cohosh

Complementary and alternative medicines (CAM) such as isoflavones and black cohosh are commonly used to deal with menopausal symptoms, but benefit a limited proportion of women. The aim of this minireview is to summarize the evidence of the efficacy and safety of other herbal preparations. Randomized controlled trials (RCTs) find that the extracts of Mediterranean pine bark (Pycnogenol(®)), linseed, and Lepididium meyenii (Maca) reduce vasomotor symptoms. The results of RCTs of the hop flavonoid 8-prenylnaringenin are conflicting. Animal and human studies suggest that Dioscorea villosa (Wild yam),and Broccoli may protect against osteoporosis and breast and gynecological cancers but further evidence is required. Linseed may protect against breast cancer but the results are conflicting.

Flax and Breast Cancer

Background. Flax is a food and dietary supplement commonly used for menopausal symptoms. Flax is known for its lignan, α-linolenic acid, and fiber content, components that may possess phytogestrogenic, anti-inflammatory, and hormone modulating effects, respectively. We conducted a systematic review of flax for efficacy in improving menopausal symptoms in women living with breast cancer and for potential impact on risk of breast cancer incidence or recurrence. Methods. We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to January 2013 for human interventional or observational data pertaining to flax and breast cancer. Results. Of 1892 records, we included a total of 10 studies: 2 randomized controlled trials, 2 uncontrolled trials, 1 biomarker study, and 5 observational studies. Nonsignificant (NS) decreases in hot flash symptomatology were seen with flax ingestion (7.5 g/d). Flax (25 g/d) increased tumor apoptotic index ( P < .05) and decreased HER2 expression ( P < .05) and cell proliferation (Ki-67 index; NS) among newly diagnosed breast cancer patients when compared with placebo. Uncontrolled and biomarker studies suggest beneficial effects on hot flashes, cell proliferation, atypical cytomorphology, and mammographic density, as well as possible anti-angiogenic activity at doses of 25 g ground flax or 50 mg secoisolariciresinol diglycoside daily. Observational data suggests associations between flax and decreased risk of primary breast cancer (adjusted odds ratio [AOR] = 0.82; 95% confidence interval [CI] = 0.69-0.97), better mental health (AOR = 1.76; 95% CI = 1.05-2.94), and lower mortality (multivariate hazard ratio = 0.69; 95% CI = 0.50-0.95) among breast cancer patients. Conclusions. Current evidence suggests that flax may be associated with decreased risk of breast cancer. Flax demonstrates antiproliferative effects in breast tissue of women at risk of breast cancer and may protect against primary breast cancer. Mortality risk may also be reduced among those living with breast cancer.

Lignans extracted from Vitex negundo possess cytotoxic activity by G2/M phase cell cycle arrest and apoptosis induction

Evn-50 is a lignan compounds mixture extracted from Vitex negundo, a widely used herb in traditional Chinese medicine. This study is aimed to define the spectrum of cytotoxic activity of EVn-50, and also to investigate mechanisms underlying the anticancer actions via assessing the influence on cell cycle using EVn-50, and the lignan compound VB1 purified from EVn-50. The cytotoxic effect of EVn-50 and VB1 was determined with SRB assay using a panel of cancer cell lines. Breast cancer cell line MDA-MB-435 and liver cancer cell line SMMC-7721 were selected for further evaluating the effect of EVn-50 or VB1 on cell cycle by flow cytometric analysis. Apoptosis exerted by EVn-50 or VB1 was measured by TUNEL assay and DAPI staining, and Western blot analysis was utilized to assess the influence on expression and phosphorylation of proteins which are closely related to cell cycle and apoptosis. EVn-50 possessed a broad spectrum of in vitro anticancer activity for those tested cancer cells, especially sensitive to MDA-MB-435, SKOV-3, BXPC-3, SMMC-7721, MCF-7, HO-8910, SGC-7901, BEL-7402, HCT-116, and 786-O, with the respective IC50 below 10 μg/ml. Treatment with EVn-50 or VB1 resulted in arresting the MDA-MB-435 and SMMC-7721 cells at G2/M phase, which was further supported by observations of increased phosphorylation of Histone 3 at Ser10, phosphorylation of Cdk1 at Tyr15, expression of cyclin B1, and decreased expression of Cdc25c. Moreover, we found that exposure of MDA-MB-435 cells to EVn-50 or VB1 caused obvious apoptosis of MDA-MB-435 cells. Our data show that EVn-50, lignan compounds extracted from Vitex negundo, possesses a broad spectrum cytotoxic effect via arresting cancer cells at G2/M phase cell cycle and subsequently inducing apoptosis.

Polymorphisms in oxidative stress-related genes and mortality in breast cancer patients--potential differential effects by radiotherapy?

We assessed whether variants in 22 oxidative stress-related genes are associated with mortality of breast cancer patients and whether the associations differ according to radiotherapy. Using a prospective cohort of 1348 postmenopausal breast cancer patients, we estimated hazard ratios (HR) and 95% confidence intervals (CI) for 109 single nucleotide polymorphisms (SNPs) using Cox proportional hazards regression. Validation of results was attempted using two Scandinavian studies. Eleven SNPs in MT2A, NFE2L2, NQO1, PRDX1, and PRDX6 were significantly associated with overall mortality after a median follow-up of 5.7 years. Three SNPs in NQO1 (rs2917667) and in PRDX6 (rs7314, rs4916362) were consistently associated with increased risk of dying across all three study populations (pooled: HRNQO1_rs2917667 1.20, 95% CI 1.00-1.44, p = 0.051; HRPRDX6_rs7314 1.16, 95% CI 1.00-1.35, p = 0.056, HRPRDX6_rs4916362 1.14 95% CI 1.00-1.32, p = 0.062). Potential effect modification by radiotherapy was found for CAT_rs769218. In conclusion, genetic variants in NQO1 and PRDX6 may modify breast cancer prognosis.

CD24 polymorphisms in breast cancer: impact on prognosis and risk

Overexpression of CD24 has a negative impact on breast cancer prognosis. We have recently reported that the CD24 codon 57 Val/Val genotype (rs52812045) is associated with pathologic complete response after neoadjuvant chemotherapy for primary breast cancer and correlates with intratumoral lymphocyte infiltrates. This study was performed to investigate the influence of CD24 polymorphisms on breast cancer prognosis and risk. A total of 2,514 patients and 4,858 controls recruited as part of the MARIE study, a population-based case-control study, were genotyped for two CD24 polymorphisms (rs52812045, rs3838646) using TaqMan custom genotyping assays. Associations with overall and breast cancer-specific survival were assessed using uni- and multivariable Cox regression models stratified by age at diagnosis and adjusted for prognostic factors. Conditional logistic regression analysis adjusted for major risk factors was used to estimate multivariable odds ratios for risk of putative allele carriers compared to wildtype carriers. CD24 Ala/Val was significantly associated with breast cancer prognosis [Val/Val hazard ratio (HR)(adjusted) = 1.52; 95 % confidence interval (CI): 1.00-2.30, p = 0.05 and HR(adjusted) = 1.83; 95 % CI: 1.10-3.05, p = 0.018 for all-cause and breast cancer-specific mortality, respectively). The association was significant only in patients with a BMI <25 and in those who received adjuvant chemotherapy. None of the CD24 alleles was associated with breast cancer risk. These results provide further evidence of the CD24 Val/Val genotype influencing outcome in primary breast cancer. Together with previous data of CD24 overexpression as a poor prognostic marker, the findings underline the biological importance of CD24 for breast cancer.

Estradiol, tamoxifen, and flaxseed alter IL-1β and IL-1Ra levels in normal human breast tissue in vivo

INTRODUCTION

Sex steroid exposure increases the risk of breast cancer by unclear mechanisms. Diet modifications may be one breast cancer prevention strategy. The proinflammatory cytokine family of IL-1 is implicated in cancer progression. IL-1Ra is an endogenous inhibitor of the proinflammatory IL-1α and IL-1β.

OBJECTIVE

The objective of this study was to elucidate whether estrogen, tamoxifen, and/or diet modification altered IL-1 levels in normal human breast tissue.

DESIGN AND METHODS

Microdialysis was performed in healthy women under various hormone exposures, tamoxifen therapy, and diet modifications and in breast cancers of women before surgery. Breast tissue biopsies from reduction mammoplasties were cultured.

RESULTS

We show a significant positive correlation between estradiol and in vivo levels of IL-1β in breast tissue and abdominal sc fat, whereas IL-1Ra exhibited a significant negative correlation with estradiol in breast tissue. Tamoxifen or a dietary addition of 25 g flaxseed per day resulted in significantly increased levels of IL-1Ra in the breast. These results were confirmed in ex vivo culture of breast biopsies. Immunohistochemistry of the biopsies did not reveal any changes in cellular content of the IL-1s, suggesting that mainly the secreted levels were affected. In breast cancer patients, intratumoral levels of IL-1β were significantly higher compared with normal adjacent breast tissue.

CONCLUSION

IL-1 may be under the control of estrogen in vivo and may be attenuated by antiestrogen therapy and diet modifications. The increased IL-1β in breast cancers of women strongly suggests IL-1 as a potential therapeutic target in breast cancer treatment and prevention.

Impact of Diet, Body Mass Index, and Physical Activity on Cancer Survival

With the increase in the number of cancer patients worldwide in the coming years, the need for knowledge on the influence of lifestyle factors on cancer survival is increasing. In this paper, the current knowledge on diet, body mass index, and physical activity in relation to cancer outcome is summarized. Also, challenges are identified to be addressed to provide evidence-based recommendations for cancer patients. Studies in patients with breast, colorectal, or prostate cancer show that the influence of dietary factors on survival remains to be determined. Adiposity and a lack of physical activity, however, appear to influence cancer outcome negatively. Subsequent studies should focus on more detailed aspects of these lifestyle factors, such as body composition and dose of exercise, and on the timing with respect to diagnosis and treatment. Research should be directed toward investigating diet and physical activity simultaneously and on how changes in health behavior can be established.