Breast cancer risk during HRT: influence of estradiol metabolites on breast cancer and endothelial cell proliferation

The Correlation Between Progesterone and Mammographic Density in Postmenopausal Women: A Systematic Review of the Literature and Meta-Analysis

Higher mammographic breast density in premenopausal and postmenopausal women is related to a higher breast cancer risk. In this review, we analyze the correlation between estrogen, progesterone, and mammographic density in postmenopausal women and clarify whether these findings are consistent across different types of mammographic breast density. We extracted data concerning mammographic density increases in the populations treated with estrogen-only hormone replacement therapy and those treated with estrogen and progestin hormone replacement therapy. Postmenopausal women treated with estrogen and progesterone regimens had a statistically significant lesser mammographic density increase than estrogen-only hormone replacement therapy regimens.

In Silico Prediction of Steroids and Triterpenoids as Potential Regulators of Lipid Metabolism

This review focuses on a rare group of steroids and triterpenoids that share common properties as regulators of lipid metabolism. This group of compounds is divided by the type of chemical structure, and they represent: aromatic steroids, steroid phosphate esters, highly oxygenated steroids such as steroid endoperoxides and hydroperoxides, α,β-epoxy steroids, and secosteroids. In addition, subgroups of carbon-bridged steroids, neo steroids, miscellaneous steroids, as well as synthetic steroids containing heteroatoms S (epithio steroids), Se (selena steroids), Te (tellura steroids), and At (astatosteroids) were presented. Natural steroids and triterpenoids have been found and identified from various sources such as marine sponges, soft corals, starfish, and other marine invertebrates. In addition, this group of rare lipids is found in fungi, fungal endophytes, and plants. The pharmacological profile of the presented steroids and triterpenoids was determined using the well-known computer program PASS, which is currently available online for all interested scientists and pharmacologists and is currently used by research teams from more than 130 countries of the world. Our attention has been focused on the biological activities of steroids and triterpenoids associated with the regulation of cholesterol metabolism and related processes such as anti-hyperlipoproteinemic activity, as well as the treatment of atherosclerosis, lipoprotein disorders, or inhibitors of cholesterol synthesis. In addition, individual steroids and triterpenoids were identified that demonstrated rare or unique biological activities such as treating neurodegenerative diseases, Alzheimer's, and Parkinson's diseases with a high degree of certainty over 95 percent. For individual steroids or triterpenoids or a group of compounds, 3D drawings of their predicted biological activities are presented.

Effect of Vitamin D Supplementation on Risk of Breast Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective: Laboratory findings indicated that vitamin D might have a potent protective effect on breast cancer, but epidemiology studies reported conflicting results. The aim of the study was to conduct a systematic review and meta-analysis to clarify the efficacy of vitamin D supplementation on risk of breast cancer.

Methods: MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and abstracts of three major conferences were searched (up to December 8, 2020). Parallel randomized controlled trials (RCTs) examining the efficacy of vitamin D supplementation on risk of breast cancer or change of mammography compared with placebo in females were included. Data were meta-analyzed using a random-effects model. Bayesian meta-analysis was conducted to synthesize the results using data from observational studies as priors.

Results: Seven RCTs were identified for effect of vitamin D on risk of breast cancer, with 19,137 females included for meta-analysis. No statistically significant effect of vitamin D on risk of breast cancer was found in classical random-effects meta-analysis (risk ratio = 1.04, 95% confidence interval: 0.84–1.28, p = 0.71). When Bayesian meta-analyses were conducted, results remained non-significant. There was no statistically significant effect of vitamin D on mammography density observed: mean difference = 0.46, 95% confidence interval: −2.06 to 2.98, p = 0.72.

Conclusion: There is insufficient evidence to support the efficacy of vitamin D supplementation in breast cancer risk and change of mammography density. The protective effect of vitamin D on risk of breast cancer from previous observational studies may be overestimated.

Systematic Review Registration: PROSPERO, identifier CRD42019138718.

Amphiphilic derivatives of (3β,17β)-3-hydroxyandrost-5-ene-17-carboxylic acid

A series of amphiphilic derivatives of (3β,17β)-3-hydroxyandrost-5-ene-17-carboxylic acid (1) with the polyamine spermine and three other diamines, 1,2-diaminoethane, piperazine and cadaverine, were synthesized and their antimicrobial activity and cytotoxicity were investigated. Among the target compounds, several ones showed antimicrobial activity on Gram positive and Gram negative microorganisms. The most active compounds were 20 (Streptococcus mutans CCM 7409, 3.125 µM), 16 (Streptococcus mutans CCM 7409, 12.5 µM) and 10d (Escherichia coli CCM 3954, 12.5 µM). In addition, compounds 5d, 10d, 13 and 20 displayed cytotoxicity on CEM (12.1 ± 2.1 µM, 7.6 ± 1.0 µM, 19.0 ± 0.4 µM and 5.9 ± 0.7 µM, respectively). Two additional compounds displayed medium cytotoxicity on CEM, 5a (34.6 ± 5.2 µM) and 5c (37.7 ± 5.9 µM). The compound 13 and 20 displayed high toxicity also on normal fibroblasts.

Benefits and risks during HRT: main safety issue breast cancer

To assess the benefits and risks during hormone replacement therapy (HRT) in postmenopausal women, the only placebo-controlled study testing clinical endpoints with high statistical power has been the Women's Health Initiative (WHI). Although this trial, conducted mainly in older high-risk women, might not reflect the practical conditions for the normal use of HRT, the WHI for the first time provides the main risks in relative as well as in absolute numbers, which are venous thromboembolism and breast cancer, and in older women also myocardial infarction and stroke. Proven benefits such as treatment of climacteric symptoms, reduction of osteoporotic fractures and decrease of colon cancer risk seem to be only important for younger women, because only with early start of HRT cardiovascular risks can be reduced. Reduction of cardiovascular risks can be achieved using transdermal HRT, which, however, was not tested in a placebo-controlled study design similar to that in the WHI. This review focuses on the results of the WHI, comparing different age groups, and in general especially on the main fear of women, risk of breast cancer, which has been defined as a special project between two universities, a close collaboration of a German and Chinese research group.

Synthesis of sex hormone-derived modified steroids possessing antiproliferative activity

During recent years intensive research has been focused on the synthesis of structurally modified steroid hormones in order to obtain compounds with beneficial biological activity such as cell-growth inhibition. Experimental results have revealed that some steroidal derivatives possess direct cytostatic effect on cancer cells in a hormone receptor-independent manner. After a brief account on the most important biological function and characteristics of the naturally occurring sex hormones in physiological and pathological conditions, structural modifications of estrane and androstane scaffolds are discussed in detail. The review covers literature publications (from 2002 to 2012) relating to the synthesis and antiproliferative activity of semisynthetic sex hormone-derived molecules containing simple or heterocyclic substituents. The compounds reviewed are divided into three main categories according to their sterane framework and the nature of substitution. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Regulatory decisions on endocrine disrupting chemicals should be based on the principles of endocrinology

For years, scientists from various disciplines have studied the effects of endocrine disrupting chemicals (EDCs) on the health and wellbeing of humans and wildlife. Some studies have specifically focused on the effects of low doses, i.e. those in the range that are thought to be safe for humans and/or animals. Others have focused on the existence of non-monotonic dose-response curves. These concepts challenge the way that chemical risk assessment is performed for EDCs. Continued discussions have clarified exactly what controversies and challenges remain. We address several of these issues, including why the study and regulation of EDCs should incorporate endocrine principles; what level of consensus there is for low dose effects; challenges to our understanding of non-monotonicity; and whether EDCs have been demonstrated to produce adverse effects. This discussion should result in a better understanding of these issues, and allow for additional dialog on their impact on risk assessment.

Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort

Background:

We investigated associations of known breast cancer risk factors with breast density, a well-established and very strong predictor of breast cancer risk.

Methods:

This nested case–control study included breast cancer-free women, 265 with high and 860 with low breast density. Women were required to be 40–80 years old and should have a body mass index (BMI) <35 at the time of the index mammogram. Information on covariates was obtained from annual questionnaires.

Results:

In the overall analysis, breast density was inversely associated with BMI at mammogram (P for trend<0.001), and parity (P for trend=0.02) and positively associated with alcohol consumption (ever vs never: odds ratio 2.0, 95% confidence interval 1.4–2.8). Alcohol consumption was positively associated with density, and the association was stronger in women with a family history of breast cancer (P<0.001) and in women with hormone replacement therapy (HRT) history (P<0.001). Parity was inversely associated with density in all subsets, except premenopausal women and women without a family history. The association of parity with density was stronger in women with HRT history (P<0.001).

Conclusion:

The associations of alcohol and parity with breast density appear to be in reverse direction, but stronger in women with a family history of breast cancer and women who ever used HRT.

Vitamin D and mammographic breast density: a systematic review

Studies suggest a protective relationship between Vitamin D and breast cancer risk. Several studies assessed the association of Vitamin D with mammographic breast density, a known and strong breast cancer risk factor. Understanding the potential role of Vitamin D in the modification of breast density might open new avenues in breast cancer prevention. This systematic review summarizes published studies that investigated the association between Vitamin D and mammographic breast density and offers suggestions for strategies to advance our scientific knowledge.

Estrogens in the breast tissue: a systematic review

The role of estrogens in breast carcinogenesis has been investigated at the level of whole body (plasma) and cell (molecular, receptors, etc.). Growing attention focused on the breast tissue being an intracrine organ, with potentially important local estrogen production in the breast. However, very little is known about the local breast tissue estrogen levels. Understanding the role of the tissue estrogens in breast carcinogenesis might open new avenues in breast cancer prevention. This systematic review summarizes published studies that measured local estrogen levels in the breast and offers suggestions for strategies to fill gaps in our existing scientific knowledge.

Are estradiol metabolites involved in gynaecological carcinogenesis?

Certain estradiol metabolites are biologically active, sometimes several times more potent than their parent substance. Highly sophisticated laboratory methods allow us to understand oestrogenic effects as a net effect of the corresponding metabolite pattern. Currently, research is focused on the anticancerogenic effects of 2-hydroxyestrone and particularly 2-methoxyestradiol, as well as the possible carcinogenic properties of 4-hydroxyoestrogens and 16α-hydroxyestrone. The clinical relevance of these activities, demonstrated in in-vitro and animal experiments, remains unclear - it is proven, however, that the metabolite production can be altered in certain malignancies such as endometrial-, breast- and cervical carcinoma. Clinical studies, including our studies, have demonstrated a negative correlation between the ratio of 2-hydroxyestrone to 16α-hydroxyestrone and breast cancer risk. However, the design and interpretation of such studies should consider factors influencing metabolic pattern such as diet, physical activity, smoking, as well as internal diseases and certain drugs.

Adrenaline: communication by electron emission. Effect of concentration and temperature. Product analysis

Based on the recent findings about the ability of sexual hormones to emit electrons (e

Highest purity adrenaline (ADR) and chemicals were used for preparation of aqueous solutions (pH ∼7.4). The excitation of ADR in singlet state was achieved by irradiation of airfree aqueous solution with monochromatic UV light at λ=254 nm. The emitted “solvated electrons” (e

It was found that Q(e

The 4-hydroxyestrone: Electron emission, formation of secondary metabolites and mechanisms of carcinogenesis

4-Hydroxyestrone (4-OHE(1)), a typical cancer-inducing metabolite, originating from 17beta-estradiol (17beta-E2), was chosen as a model for the studies. The aim was to get a deeper insight in the mechanisms of its ability to initiate cancer. It was found, that 4-OHE(1) can eject electrons (e(aq)(-)), when excited in the singlet state by monochromatic UV-light (lambda=254 nm) in polar media (water:ethanol=40:60 vol.%). The quantum yield Q(e(aq)(-)), determined for various 4-OHE(1) concentrations, is found to be as high as that previously observed for 17beta-E2. It decreases with increasing substrate concentration, but it is enhanced at higher temperature. The ability of 4-OHE(1) to eject as well as to consume and to transfer electrons to other biological systems, classifies it as an electron mediator, similar to 17beta-E2. The 4-OHE(1) transients resulting of the electron emission process are leading to the formation of secondary metabolites. Surprisingly, it was established that the secondary metabolites possess likewise the ability to eject as well as to consume electrons. Hence, they behave similar like 17beta-E2. However, the structure of the secondary formed metabolites, which determinates their biological properties and carcinogenity, depends on the nature of the available reaction partners involved in their formation. A probable reaction mechanism explaining the subject matter is discussed.

Electron emission from photo-excited testosterone in water-ethanol solution

Testosterone (TES; 4-androstene-17beta-ol-3-on) is found for the first time to eject electrons from its singlet excited state in water-ethanol solvent mixture. This ability was very recently also observed for 17beta-estradiol (17betaE2) and progesterone (PRG)/1/. With increasing TES-concentration, the yield of solvated electrons (e(s)(-)) is decreasing, because of "associate" formation. At higher absorbed UV-doses (lambda=254 nm) the e(s)(-) yield is passing a sharp maximum by formation of TES-ethanol adducts, which are able likewise to emit electrons when excited. At prolonged irradiation the resulting photolytic products of TES-ethanol adducts are also able to emit electrons. The capability of the hormones: 17betaE2, PRG and TES to eject electrons and the resulting metabolites, some of which can induce cancer, is discussed.

Contribution of alpha2-adrenoceptors to the mitogenic effect of catecholestrogen in human breast cancer MCF-7 cells

Catecholestrogens are estrogen metabolites formed by hydroxylation of 17beta-estradiol and estrone at either the C-2 or C-4 position, rivaling the parent estrogens in concentration. The objective of the present work was to assess if their catechol group could make them induce proliferation of human breast cancer cells via alpha(2)-adrenoceptors. In competition studies in human breast cancer MCF-7 cells, high concentrations of 2-hydroxy-estradiol (2-OH-E(2)), 2-hydroxy-estrone (2-OH-E(1)) and 4-hydroxy-estrone (4-OH-E(1)) competed for [(3)H]-rauwolscine binding, whereas 4-hydroxy-estradiol (4-OH-E(2)) did not. The contribution of alpha(2)-adrenoceptors and estrogen receptors (ERs) in proliferation enhancement was analyzed with specific antagonists. The specific alpha(2)-adrenergic antagonist yohimbine partially reversed the effect of catecholestrogens except 4-OH-E(2). The selective ER downregulator ICI-182780 or fulvestrant partially or totally reversed the effect of all hydroxylated catecholestrogens. When analyzing the effect of the combination of both antagonists in MCF-7, the contribution of the alpha(2)-adrenoceptors and ERs for 2-OH-E(2), 2-OH-E(1) and 4-OH-E(1) was mixed, whereas for 4-OH-E(2), the only receptor implied was an ER. In MDA-MB-231 cells (ER-alpha negative) the proliferation stimulation by these three catecholestrogens and reversal by the adrenergic antagonist was also observed. It can be concluded that alpha(2)-adrenoceptors contribute at least in part to the mitogenic effect of 2-OH-E(2), 2-OH-E(1) and 4-OH-E(1).

Photo-induced electron emission from 17beta-estradiol and progesterone and possible biological consequences

It was established for the first time, that the sexual hormones 17beta-estradiol (17betaE2) and progesterone (PRG) are able to emit electrons from their excited single state in water-ethanol mixtures. The yield of the "solvated electrons" (e(s)(-)) depends on the substrate concentration, the ratio of water-alcohol-mixtures and the temperature. The e(s)(-) yield obtained from 17betaE2 is by two orders of magnitude higher than this of PRG. The possible relationship of the resulting hormone transients from 17betaE2 leading via specific metabolites to breast cancer is discussed.

Different effects of estradiol and various antiestrogens on TNF-alpha-induced changes of biochemical markers for growth and invasion of human breast cancer cells

In the field of estrogen therapy breast cancer risk is one of the most controversially discussed topic. Actually, the as yet largest placebo-controlled study, the Women's Health Initiative, rather showed a risk reduction, in contrast to observational studies. In the present study we have investigated the effect of estradiol on TNF-alpha-induced changes of various markers in human breast cancer cells and compare it with the effect of the antiestrogens tamoxifen and 2-methoxyestradiol. MCF-7 cells were used for the experiments, the incubation time was 96 h. TNF-alpha elicited a 3-4-fold increase of monocyte-attracting protein-1 (MCP-1) and interleukin-8 (IL-8) as compared to the control value, matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) were enhanced by 30 to 40%. E2 alone had no effect on MCP-1, slightly reduced the synthesis of MMP-9 and increased VEGF concentrations by about 20%. In combination with TNF, E2 induced a further stimulation of MCP-1, IL-8 and VEGF, whereby the MMP-9 synthesis was not changed. Tamoxifen and the endogenous estradiol metabolite 2-methoxyestradiol seem to be able to partly inhibit the action of TNF-alpha and estradiol. Our results suggest that estrogens may slightly increase tumor growth and spreading beyond the effect of chemokines such as TNF-alpha. However, the magnitude of this E2 effect seems to be marginal as compared to the effect of TNF-alpha alone. The risk of recurrence of breast cancer in patients taking hormone therapy after breast cancer may be slightly enhanced by estrogens, but seems mainly to be driven by the potency of still existing tumor cells to secrete chemokines which can stimulate tumor growth and spreading.