The serum estradiol concentration is the main determinant of the estradiol concentration in normal breast tissue.

BACKGROUND: The estrogen concentration has been determined in breast tissue, focusing largely on samples obtained from breast cancers. In this study, estradiol concentration was determined in normal breast tissue obtained from women undergoing esthetic, and oncoplastic surgery. METHODS: Normal breast tissue was obtained during 68 operations for esthetic or reconstructive indications in women with and without a history of breast cancer. Our study included six different groups of women. The first three groups were normal cycling women, women taking oral contraceptives, and normal postmenopausal women, all undergoing a bilateral esthetic breast reduction. The second three groups were premenopausal and postmenopausal women, with a history of breast cancer and currently taking tamoxifen treatment, or postmenopausal women currently taking an aromatase inhibitor, needing contra-lateral corrective esthetic surgery. FINDINGS: In the group of women without history of breast cancer, normal cycling women (n=24) presented a strong correlation (r=0.853; P<0.0001) between 17ß-estradiol concentration in serum (median: 29.7 pg/mL; IQR: 10.8-82.3 pg/mL) and in breast tissue (30.6 pg/g; IQR: 18.6-183.8 pg/g). Postmenopausal women had low 17ß-estradiol concentrations both in serum and breast tissue (r=0.813; P<0.0001, n=16). Women taking oral contraceptives (n=12) had low serum and breast tissue levels of estradiol (r=0.376; P=n.s.). Premenopausal women (n=6, mean age: 44.2 years) with a history of breast cancer and currently taking tamoxifen, had very high concentrations of 17ß-estradiol both in serum (277.9 pg/mL; IQR: 96.2-544.7 pg/mL) and in epithelial cells (251.9 pg/g; IQR: 115.0-426.5 pg/g) (r=0.803; P<0.001). Postmenopausal women taking tamoxifen (n=4, mean age: 48.3) had low concentrations of 17ß-estradiol in serum (7.0 pg/mL; IQR: 5.7-16.3 pg/mL) and in epithelial cells (14.6 pg/g IQR: 13.3-16.3 pg/g) (r=0.10; P=n.s.). The estradiol concentration in the breast of premenopausal women taking tamoxifen was 8.2 times higher that observed in the breast of normal cycling women, and 17.3 times higher that observed in postmenopausal women taking tamoxifen. Women taking adjuvant aromatase inhibitors had extremely low concentrations of 17ß-estradiol both in serum and in breast tissue. INTERPRETATION: This study shows that serum estradiol levels largely determine estrogen levels in normal breast tissue.

Soy consumption during menopause.

In developed countries, the life expectancy of women is currently extending more than 30 years beyond the age of menopause. The menopausal transition is often associated with complaints. The conflicting results on the effectivity of phytoestrogens to alleviate menopausal symptoms. This discrepancy in treatment effect may be due to the large interindividual variation in isoflavone bioavailability in general and equol production in particular. Equol, a microbial metabolite of daidzein, has been hypothesized as a clue to the effectiveness of soy and its isoflavones, but only about 30-50% of the population harbor an intestinal microbial ecosystem supporting the conversion of daidzein into equol. There is much concern on breast cancer, since this incidence of this disease increases with age. There is indication that soy phytoestrogens may decrease this breast cancer incidence. In order to evaluate the estrogenic potential of these exposure levels, we studied the isoflavone-derived E2α- and E2ß-equivalents (i.e. 17ß-estradiol (E2)-equivalents towards ERα and ERß, respectively) in human breast tissue. Total isoflavones showed a breast adipose/glandular tissue distribution of 40/60 and their derived E2ß-equivalents exceeded on average 21 ±â€ˆ4 and 40 ±â€ˆ10 times the endogenous E2 concentrations in corresponding adipose and glandular biopsies, respectively, whereas the E2α/E2 ratios were 0.4 ±â€ˆ0.1 and 0.8 ±â€ˆ0.2 in adipose and glandular breast tissue, respectively. These calculations suggest that, at least in this case, soy consumption could elicit partial ERß agonistic effects in human breast tissue. We are currently characterizing the differential activation of estrogen-responsive genes between dietary isoflavones, the chemopreventive selective ER modulators tamoxifen and raloxifene and exogenous estrogens in a controlled dietary intervention trial that integrates data on the exposure to estrogenically active compounds, expression of isoflavone and estrogen target genes, and epigenetic events. During the menopause, there is a close relation between the drop in serum estrogen and negative metabolic changes such as the increase in bone resorption and negative change in the serum lipid profile. Randomized controlled trials measuring bone turnover markers in menopausal women revealed that soy isoflavone supplements significantly but moderately decrease the bone resorption marker urinary deoxypyridinoline without significant effects on the bone formation markers serum bone alkaline phosphatase and osteocalcin.

Novel approaches for analysing gut microbes and dietary polyphenols: challenges and opportunities.

Polyphenols, ubiquitously present in the food we consume, may modify the gut microbial composition and/or activity, and moreover, may be converted by the colonic microbiota to bioactive compounds that influence host health. The polyphenol content of fruit and vegetables and derived products is implicated in some of the health benefits bestowed on eating fruit and vegetables. Elucidating the mechanisms behind polyphenol metabolism is an important step in understanding their health effects. Yet, this is no trivial assignment due to the diversity encountered in both polyphenols and the gut microbial composition, which is further confounded by the interactions with the host. Only a limited number of studies have investigated the impact of dietary polyphenols on the complex human gut microbiota and these were mainly focused on single polyphenol molecules and selected bacterial populations. Our knowledge of gut microbial genes and pathways for polyphenol bioconversion and interactions is poor. Application of specific in vitro or in vivo models mimicking the human gut environment is required to analyse these diverse interactions. A particular benefit can now be gained from next-generation analytical tools such as metagenomics and metatranscriptomics allowing a wider, more holistic approach to the analysis of polyphenol metabolism. Understanding the polyphenol-gut microbiota interactions and gut microbial bioconversion capacity will facilitate studies on bioavailability of polyphenols in the host, provide more insight into the health effects of polyphenols and potentially open avenues for modulation of polyphenol bioactivity for host health.

Plant polyphenolics as anti-invasive cancer agents.

Because invasion is, either directly or via metastasis formation, the main cause of death in cancer patients, development of efficient anti-invasive agents is an important research challenge. We have established a screening program for potentially anti-invasive compounds. The assay is based on organotypic confronting cultures between human invasive cancer cells and a fragment of normal tissue in three dimensions. Anti-invasive agents appeared to be heterogeneous with regard to their chemical nature, but plant alkaloids, polyphenolics and some of their synthetic congeners were well represented. Even within this group, active compounds were quite diverse: (+)-catechin, tangeretin, xanthohumol and other prenylated chalcones, 3,7-dimethoxyflavone, a pyrazole derivative, an isoxazolylcoumarin and a prenylated desoxybenzoin. The data gathered in this system are now applied in two projects. Firstly, structure-activity relationships are explored with computer models using an artificial neural network approach, based on quantitative structural descriptors. The aim of this study is the prediction and design of optimally efficient anti-invasive compounds. Secondly, the metabolism of orally ingested plant polyphenolics by colonic bacteria is studied in a simulator of the human intestinal microbial ecosystem (SHIME) and in human intervention trials. This method should provide information on the final bioavailability of the active compounds in the human body, with regard to microbial metabolism, and the feasibility of designing pre- or probiotics that increase the generation of active principles for absorption in the gastro-intestinal tract. The final and global aim of all these studies is to predict, synthesize and apply in vivo molecules with an optimal anti-invasive, and hence an anti-metastatic activity against cancer.