Aromatase in aging women

Age-stratified risk factors of re-intervention for uterine fibroids treated with high-intensity focused ultrasound

OBJECTIVE

To estimate the rate and risk factors of re-intervention for patients with uterine fibroids (UFs) undergoing high-intensity focused ultrasound (HIFU) at different age distributions.

METHOD

A retrospective cohort study was conducted in Nanchong Central Hospital, recruiting a total of 672 patients with UFs undergoing HIFU from June 2017 to December 2019. Using univariate and multivariate logistic regression, risk factors for re-intervention were assessed.

RESULTS

Among 401 patients with UFs who completed the follow-up visits (median 47 months, range 34-61), 50 (12.46%) patients underwent re-intervention (such as high-intensity focused ultrasound, uterine artery embolization, myomectomy and hysterectomy). In the different age distributions, the re-intervention rate was 17.5% (34/194) in patients aged <45 years and 7.7% (16/207) in those aged ≥45 years. Regarding the younger patient group (aged <45 years), hypo- or iso-intensive fibroids in T2-weighted magnetic resonance imaging (T2WI) intensity may elevate the risk of re-intervention for UFs (odds ratio [OR] 2.96, 95% confidence interval [CI] 1.37-6.62; P = 0.007). Among the older patient group (aged ≥45 years), preoperative anemic patients had an increased risk of re-intervention compared with those without anemia (OR 3.30, 95% CI 1.01-10.37; P = 0.041).

CONCLUSION

The re-intervention rate of HIFU decreased with increasing age. Among those aged <45 years, T2WI intensity was the independent risk factor for re-intervention, and among those aged ≥45 years, preoperative anemic status may be related to re-intervention outcome.

Possible implication of estrogenic compounds on heart disease in menopausal women

Epidemiological studies imply there is a higher risk of cardiovascular disease in menopausal women. Some explanations suggest a lack of estrogens as the cause, but estrogens do not disappear completely and are just transformed into different products called estrogenic degradation metabolites (EDMs). When estrogens are metabolized, reactive oxygen species (ROS) increase, causing DNA damage and increasing oxidative stress. These conditions are associated to neurodegenerative diseases and different types of cancer. However, their effect on the cardiovascular system remains unknown. This paper compares estrogenic metabolite levels in serum from post-menopausal women with cardiovascular risk (CAC>1) and with establish cardiovascular disease (CVD), against levels in healthy women (Ctrl). Sample sera were obtained from the Genetics of Atherosclerotic Disease (GEA) Mexican Study. Serum levels of eleven estrogenic metabolites were quantified by High performance liquid chromatography (HPLC) and oxidative stress markers such as ROS, lipoperoxidation levels (TBARS), total antioxidant capacity (TAC), super oxide dismutase activity (SOD) and cytokine levels were evaluated. 8-hydroxy-2-deoxyguanosine (8-OHdG) was also determined as a marker of nuclear damage.There were significant differences between serum levels of some EDMs in CAC> 1 and CVD vs. serum levels in Ctrl women. Results also revealed an increase in oxidative stress and a diminished capacity to manage oxidative stress. These findings provide an overview, and suggest that some estrogenic metabolites may be associated with an increased risk of CVD in menopausal women. However, additional studies are needed to evaluate the impact of these EDMs directly on cardiovascular function.

Aromatase and steroid sulfatase from human placenta

Cytochrome P450 aromatase (AROM) and steroid (estrone (E1)/dehydroepiandrosterone (DHEA)) sulfatase (STS) are the two key enzymes responsible for the biosynthesis of estrogens in human, and maintenance of the critical balance between androgens and estrogens. Human AROM, an integral membrane protein of the endoplasmic reticulum, is a member of the Fe-heme containing cytochrome P450 superfamily having a cysteine thiolate as the fifth Fe-coordinating ligand. It is the only enzyme known to catalyze the conversion of androgens with non-aromatic A-rings to estrogens characterized by the aromatic A-ring. Human STS, also an integral membrane protein of the endoplasmic reticulum, is a Ca2+-dependent enzyme that catalyzes the hydrolysis of sulfate esters of E1 and DHEA to yield the respective unconjugated steroids, the precursors of the most potent forms of estrogens and androgens, namely, 17β-estradiol (E2), 16α,17β-estriol (E3), testosterone (TST) and dihydrotestosterone (DHT). Expression of these steroidogenic enzymes locally within various organs and tissues of the endocrine, reproductive, and central nervous systems is the key for maintaining high levels of the reproductive steroids. Thus, the enzymes have been drug targets for the prevention and treatment of diseases associated with steroid hormone excesses, especially in breast and prostate malignancies and endometriosis. Both AROM and STS have been the subjects of vigorous research for the past six decades. In this article, we review the procedures of their extraction and purification from human term placenta are described in detail, along with the activity assays.

Structures and Functions of Human Placental Aromatase and Steroid Sulfatase, Two Key Enzymes in Estrogen Biosynthesis

Cytochrome P450 aromatase (AROM) and steroid sulfatase (STS) are the two key enzymes for the biosynthesis of estrogens in human, and maintenance of the critical balance between androgens and estrogens. Human AROM, an integral membrane protein of the endoplasmic reticulum, is a member of the cytochrome P450 superfamily. It is the only enzyme to catalyze the conversion of androgens with non-aromatic A-rings to estrogens characterized by the aromatic A-ring. Human STS, also an integral membrane protein of the endoplasmic reticulum, is a Ca²⁺-dependent enzyme that catalyzes the hydrolysis of sulfate esters of estrone and dehydroepiandrosterone to the unconjugated steroids, the precursors of the most potent forms of estrogens and androgens, namely, 17β-estradiol, 16α,17β-estriol, testosterone and dihydrotestosterone. Expression of these steroidogenic enzymes locally within organs and tissues of the endocrine, reproductive, and central nervous systems is the key for maintaining high levels of the reproductive steroids. The enzymes have been drug targets for the prevention and treatment of diseases associated with steroid hormone excesses, especially in breast, endometrial and prostate malignancies. Both enzymes have been the subjects of vigorous research for the past six decades. In this article, we review the important findings on their structure-function relationships, specifically, the work that began with unravelling of the closely guarded secrets, namely, the 3-D structures, active sites, mechanisms of action, origins of substrate specificity and the basis of membrane integration. Remarkably, these studies were conducted on the enzymes purified in their pristine forms from human placenta, the discarded and their most abundant source. The purification, assay, crystallization, and structure determination methodologies are described. Also reviewed are their functional quaternary organizations, post-translational modifications and the advancements made in the structure-guided inhibitor design efforts. Outstanding questions that still remain open are summarized in closing.

Low-dose aspirin and risk of breast cancer: a Norwegian population-based cohort study of one million women

Several studies evaluated the association between aspirin use and risk of breast cancer (BC), with inconsistent results. We identified women aged ≥ 50 years residing in Norway between 2004 and 2018, and linked data from nationwide registries; including the Cancer Registry of Norway, the Norwegian Prescription Database, and national health surveys. We used Cox regression models to estimate the association between low-dose aspirin use and BC risk, overall and by BC characteristics, women's age and body mass index (BMI), adjusting for sociodemographic factors and use of other medications. We included 1,083,629 women. During a median follow-up of 11.6 years, 257,442 (24%) women used aspirin, and 29,533 (3%) BCs occurred. For current use of aspirin, compared to never use, we found an indication of a reduced risk of oestrogen receptor-positive (ER +) BC (hazard ratio [HR] = 0.96, 95% confidence interval [CI]: 0.92-1.00), but not ER-negative BC (HR = 1.01, 95%CI: 0.90-1.13). The association with ER + BC was only found in women aged ≥ 65 years (HR = 0.95, 95%CI: 0.90-0.99), and became stronger as the duration of use increased (use of ≥ 4 years HR = 0.91, 95%CI: 0.85-0.98). BMI was available for 450,080 (42%) women. Current use of aspirin was associated with a reduced risk of ER + BC in women with BMI ≥ 25 (HR = 0.91, 95%CI: 0.83-0.99; HR = 0.86, 95%CI: 0.75-0.97 for use of ≥ 4 years), but not in women with BMI < 25.Use of low-dose aspirin was associated with reduced risk of ER + BC, in particular in women aged ≥ 65 years and overweight women.

Androstenedione and Follicle-Stimulating Hormone Concentration Predict the Progression of Frailty Syndrome at One Year Follow-Up in Patients with Localized Breast Cancer Treated with Aromatase Inhibitors

Background: The standard treatment in postmenopausal women with estrogen- and progesterone-positive localized breast cancer consists of aromatase inhibitors (AROi). The ability of AROi to promote or worsen frailty syndrome over time and the relationship with changes in gonadal hormones concentration in blood have not been investigated. Methods: A prospective study to evaluate the relationship between frailty syndrome and gonadal hormones concentrations in blood at baseline (prior to AROi treatment) and after 6 and 12 months under AROi treatment in post-menopausal women with breast cancer. Frailty syndrome was evaluated by the Fried’ criteria. We evaluated whether hormone concentration at baseline could predict frailty syndrome at follow-up. Results: Multinomial regression analysis showed that of the different hormones, those significantly (p < 0.05) associated to the worsening of frailty syndrome were high androstenedione levels and low follicle-stimulating hormone (FSH) levels in blood. Receiver operating characteristic curve analysis showed both androstenedione and FSH significantly (p < 0.05) discriminate patients who developed or presented worsening of frailty syndrome over time, with acceptable sensitivity (approximately 80% in both cases) but low specificity (40%). Conclusion: Hormonal concentrations before AROi treatment constitute possible biomarkers to predict the progression of frailty syndrome.

Endometrial Cancer as a Metabolic Disease with Dysregulated PI3K Signaling: Shedding Light on Novel Therapeutic Strategies

Endometrial cancer (EC) is one of the most common malignancies of the female reproductive organs. The most characteristic feature of EC is the frequent association with metabolic disorders. However, the components of these disorders that are involved in carcinogenesis remain unclear. Accumulating epidemiological studies have clearly revealed that hyperinsulinemia, which accompanies these disorders, plays central roles in the development of EC via the insulin-phosphoinositide 3 kinase (PI3K) signaling pathway as a metabolic driver. Recent comprehensive genomic analyses showed that over 90% of ECs have genomic alterations in this pathway, resulting in enhanced insulin signaling and production of optimal tumor microenvironments (TMEs). Targeting PI3K signaling is therefore an attractive treatment strategy. Several clinical trials for recurrent or advanced ECs have been attempted using PI3K-serine/threonine kinase (AKT) inhibitors. However, these agents exhibited far lower efficacy than expected, possibly due to activation of alternative pathways that compensate for the PIK3-AKT pathway and allow tumor growth, or due to adaptive mechanisms including the insulin feedback pathway that limits the efficacy of agents. Overcoming these responses with careful management of insulin levels is key to successful treatment. Further interest in specific TMEs via the insulin PI3K-pathway in obese women will provide insight into not only novel therapeutic strategies but also preventive strategies against EC.

A-FABP and oestrogens are independently involved in the development of breast cancer

We previously reported that postmenopausal obese women exhibit increased levels of circulating adipocyte fatty acid binding protein (A-FABP), which is associated with breast cancer (BC) development. In postmenopause, increased oestrogen levels are reported to be associated with increased BC risk. Herein, we assessed if oestrogens, including oestrone (E1), oestradiol (E2) and oestriol (E3), are associated with A-FABP in the obesity-related BC development. We collected 249 serum samples from women with or without BC and measured serum levels of E1, E2, E3 and A-FABP. Considering all subjects, E1 and E2 but not E3 levels were significantly higher in pre- than in postmenopause individuals. E3 and E1 levels were higher in non-obese than in obese women. When samples were separated by BC status, E2 levels were significantly higher, while E1 and E3 levels were significantly lower in postmenopausal obese than non-obese women without BC. These differences based on body mass index (BMI) were not observed among women with BC. E3 levels were higher in obese women with BC than those without. A-FABP levels were significantly higher in postmenopausal obese women regardless of BC status. In addition, A-FABP was not associated with E1, E2 or E3. Altogether, our data suggest that A-FABP is independently regulated by obesity and menopausal status compared to oestrogens, thus playing a unique role in the development of BC.

Local estrogen metabolism (intracrinology) in endometrial cancer: A systematic review

Endometrial cancer (EC) is the most common malignancy of the female gynaecological tract and increased exposure to estrogens is a risk factor. EC cells are able to produce estrogens locally using precursors like, among others, adrenal steroids present in the serum. This is referred to as local estrogen metabolism (or intracrinology) and consists of a complex network of multiple enzymes. Particular relevant to the final generation of active estrogens in endometrial cells are: steroid sulfatase (STS), estrogen sulfotransferase (SULT1E1), aromatase (CYP19A1), 17β-hydroxysteroid dehydrogenase (HSD17B) type 1 and type 2. During the last decades, a plethora of studies explored the level of these enzymes in EC but contrasting data were reported, which generated vigorous debate and controversies. Several reviews attempted at clarifying some of the debated issues, but published reviews are based on investigator-defined bibliography selection and not on systematic analysis. Therefore, we performed a systematic review of the literature reporting about the level of STS, SULT1E1, CYP19A1, HSD17B1 and HSD17B2 in EC. Additional intracrine enzymes and networks (e.g., HSD17Bs other than types 1 and 2, aldo-keto reductases, progesterone and androgen metabolism) were non-systematically reviewed as well.

Estrogen receptor signaling mechanisms

The primary female sex hormones, estrogens, are responsible for the control of functions of the female reproductive system, as well as the development of secondary sexual characteristics that appear during puberty and sexual maturity. Estrogens exert their actions by binding to specific receptors, the estrogen receptors (ERs), which in turn activate transcriptional processes and/or signaling events that result in the control of gene expression. These actions can be mediated by direct binding of estrogen receptor complexes to specific sequences in gene promoters (genomic effects), or by mechanisms that do not involve direct binding to DNA (non-genomic effects). Whether acting via direct nuclear effects, indirect non-nuclear actions, or a combination of both, the effects of estrogens on gene expression are controlled by highly regulated complex mechanisms. In this chapter, we summarize the knowledge gained in the past 60years since the discovery of the estrogen receptors on the mechanisms governing estrogen-mediated gene expression. We provide an overview of estrogen biosynthesis, and we describe the main mechanisms by which the female sex hormone controls gene transcription in different tissues and cell types. Specifically, we address the molecular events governing regulation of gene expression via the nuclear estrogen receptors (ERα, and ERβ) and the membrane estrogen receptor (GPER1). We also describe mechanisms of cross-talk between signaling cascades activated by both nuclear and membrane estrogen receptors. Finally, we discuss natural compounds that are able to target specific estrogen receptors and their implications for human health and medical therapeutics.

Obesity-Linked Cancers: Current Knowledge, Challenges and Limitations in Mechanistic Studies and Rodent Models

The worldwide prevalence of obesity has doubled during the last 50 years, and according to the World Obesity Federation, one third of the people on Earth will be obese by the year 2025. Obesity is described as a chronic, relapsing and multifactorial disease that causes metabolic, biomechanical, and psychosocial health consequences. Growing evidence suggests that obesity is a risk factor for multiple cancer types and rivals smoking as the leading preventable cause for cancer incidence and mortality. The epidemic of obesity will likely generate a new wave of obesity-related cancers with high aggressiveness and shortened latency. Observational studies have shown that from cancer risk to disease prognosis, an individual with obesity is consistently ranked worse compared to their lean counterpart. Mechanistic studies identified similar sets of abnormalities under obesity that may lead to cancer development, including ectopic fat storage, altered adipokine profiles, hormone fluctuations and meta-inflammation, but could not explain how these common mechanisms produce over 13 different cancer types. A major hurdle in the mechanistic underpinning of obesity-related cancer is the lack of suitable pre-clinical models that spontaneously develop obesity-linked cancers like humans. Current approaches and animal models fall short when discerning the confounders that often coexist in obesity. In this mini-review, we will briefly survey advances in the different obesity-linked cancers and discuss the challenges and limitations in the rodent models employed to study their relationship. We will also provide our perspectives on the future of obesity-linked cancer research.

Systemic Estrone Production and Injury-Induced Sex Hormone Steroidogenesis after Severe Traumatic Brain Injury: A Prognostic Indicator of Traumatic Brain Injury-Related Mortality

Extensive pre-clinical studies suggest that sex steroids are neuroprotective in experimental traumatic brain injury (TBI). However, clinical trials involving sex hormone administration have not shown beneficial results, and our observational cohort studies show systemic estradiol (E2) production to be associated with adverse outcomes. Systemic E2 is produced via aromatization of testosterone (T) or reduction of estrone (E1). E1, also produced via aromatization of androstenedione (Andro) and is a marker of T-independent E2 production. We hypothesized that E1 would be (1) associated with TBI-related mortality, (2) the primary intermediate for E2 production, and (3) associated with adipose tissue-specific aromatase transcription. We assessed 100 subjects with severe TBI and 8 healthy controls. Serum levels were measured on days 0-3 post-TBI for key steroidogenic precursors (progesterone), aromatase pathway intermediates (E1, E2, T, Andro), and the adipose tissue-specific aromatase transcription factors cortisol, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). E1 was elevated after TBI versus controls. High E1 was associated with higher progesterone, cortisol, and IL-6 (p < 0.05). Multivariable logistic regression demonstrated that those in the highest E1 tertile had increased odds for mortality (adjusted OR = 5.656, 95% CI = 1.102-29.045, p = 0.038). Structural equation models show that early serum E2 production is largely T independent, occurring predominantly through E1 metabolism. Acute serum E1 functions as a mortality marker for TBI through aromatase-dependent E1 production and T-independent E2 production. Further work should evaluate risk factors for high E2 production and how systemic E2 and its key intermediate E1 contribute to the extracerebral consequences of severe TBI.

Modulation of Tryptophan and Serotonin Metabolism as a Biochemical Basis of the Behavioral Effects of Use and Withdrawal of Androgenic-Anabolic Steroids and Other Image- and Performance-Enhancing Agents

Modulation of tryptophan (Trp) metabolism may underpin the behavioral effects of androgenic-anabolic steroids (AAS) and associated image and performance enhancers. Euphoria, arousal, and decreased anxiety observed with moderate use and exercise may involve enhanced cerebral serotonin synthesis and function by increased release of albumin-bound Trp and estrogen-mediated liver Trp 2,3-dioxygenase (TDO) inhibition and enhancement of serotonin function. Aggression, anxiety, depression, personality disorders, and psychosis, observed on withdrawal of AAS or with use of large doses, can be caused by decreased serotonin synthesis due to TDO induction on withdrawal, excess Trp inhibiting the 2 enzymes of serotonin synthesis, and increased cerebral levels of neuroactive kynurenines. Exercise and excessive protein and branched-chain amino acid intakes may aggravate the effects of large AAS dosage. The hypothesis is testable in humans and experimental animals by measuring parameters of Trp metabolism and disposition and related metabolic processes.

Low glycemic index diet, exercise and vitamin D to reduce breast cancer recurrence (DEDiCa): design of a clinical trial

BACKGROUND

Mechanisms influencing breast cancer (BC) development and recurrence include hyperglycemia, hyperinsulinemia, high insulin-like growth factor-1, high circulating estrogen, inflammation and impaired cellular differentiation/apoptosis. A lifestyle program that targets all the above mechanisms may be warranted. Low glycemic index (GI) foods produce lower post-prandial glucose and insulin responses and have been associated with lower BC risk. Moderate physical activity post-diagnosis reduces BC recurrence and mortality, partly explained by reduced insulin and estrogen levels. Vitamin D increases cell differentiation/apoptosis and high serum vitamin D levels improve BC survival. Yet no trial has evaluated the combined effect of a low GI diet, moderate physical activity and vitamin D supplementation on BC recurrence in the context of a Mediterranean lifestyle setting.

METHODS

Women (30-74 yr) who had undergone surgery for primary histologically confirmed BC (stages I-III) within the previous 12 months, in cancer centres in Italy, will be randomized to follow, for a maximum of 33 months, either a high intensity treatment (HIT) composed of low GI diet + exercise + vitamin D (60 ng/mL serum concentration) or a lower intensity treatment (LITE) with general advice to follow a healthy diet and exercise pattern + vitamin D to avoid insufficiency. Both interventions are on a background of a Mediterranean diet. Considering a 20% recurrence rate within 3 years for BC cases and a predicted rate of 10% in the HIT group, with power of 80% and two-sided alpha of 0.05, the subject number required will be 506 (n = 253 in each arm). Clinic visits will be scheduled every 3 months. Dietary and exercise counselling and vitamin D supplements will be given at each clinic visit when blood samples, anthropometric measures and 7-day food records will be collected.

DISCUSSION

DEDiCa study aims to reduce BC recurrence in women with BC using a lifestyle approach with additional vitamin D and to investigate possible cardio-metabolic benefits as well as epigenetic modifications according to lifestyle changes. Given the supporting evidence and safety of the components of our intervention we believe it is feasible and urgent to test it in cancer patients.

TRIAL REGISTRATION

May 11, 2016; NCT02786875 .

EUDRACT NUMBER

2015-005147-14.

Comparative Analysis of Proteins with Stimulating Activity on Ovarian Estradiol Biosynthesis from Four Different Dioscorea Species in vitro Using Both Phenotypic and Target-based Approaches: Implication for Treating Menopause

Rhizomes of Dioscorea species are traditionally used for relieving menopausal syndromes in Chinese medicine. The estrogen-stimulating bioactive principles have been demonstrated in our previous study. In this study, the estrogen-stimulating effects of proteins isolated from four Dioscorea species [D. alata L. (DA), D. zingiberensis C.H. Wright (DH), D. collettii var. hypoglauca (Palib.) S.J. Pei & C.T. Ting (DH), and D. oppositifolia L. (DO)] have been investigated and compared. Microscopic authentication of four Dioscorea species was performed by using paraffin and powder sections of the rhizomes. The potential bioactive proteins of four Dioscorea species have been rapidly isolated by using a DOI-antibody affinity column chromatography on immobilized antibodies against on estradiol-stimulating protein from DO (DOI), and their bioactivity has been rapidly confirmed and compared by phenotypic (i.e., estradiol-stimulating effect) and target-based (i.e., STAR, aromatase, estrogen receptors) screening approaches. The estrogen-stimulating activity of bioactive proteins from DO is the highest. In addition, bioactive proteins from DO upregulated the estradiol-metabolizing enzymes (aromatase and steroidogenic acute regulatory protein). Meanwhile, bioactive proteins from DA, DH and DO upregulated estrogen receptor β (ERβ). All bioactive proteins did not change the expression of estrogen receptor β (ERα). The estrogen-stimulating bioactive proteins isolated from DO increased biosynthesis of estradiol and upregulated the protein expression of aromatase, steroidogenic acute regulatory protein, and ERβ. The results scientifically support the traditional use of DO in Chinese medicine for relieving menopausal syndrome. Besides, proteins from DA and DZ could also upregulate the translational levels of ERβ, and potentially reducing the risk of ovarian cancer, which also support the clinical use of them for treating female aging disorder. Graphical Abstract Comparative Analysis of DOI-like Proteins with Stimulating Activity on Ovarian Estradiol Biosynthesis from Four Different Dioscorea Species in vitro.

Quantitative determination of estrone by liquid chromatography-tandem mass spectrometry in subcutaneous adipose tissue from the breast in postmenopausal women

Estrone is the most abundant estrogen after the menopause. We developed a liquid chromatography-tandem mass spectrometric method (LC-MS/MS) for determination of estrone in adipose tissue. Subcutaneous adipose tissue from the breast was collected during elective surgery in postmenopausal women undergoing mastectomy for treatment of breast cancer (n=13) or reduction mammoplasty (controls, n=11). Homogenized adipose tissue was extracted with organic solvents and the estrone fraction was purified by LH-20 column chromatography from the excess of lipids. The concentration of estrone was analyzed by LC-MS/MS. The method was accurate with an intra-assay variation of 8% and an interassay variation of 10%. The median concentration of estrone in subcutaneous adipose tissue from the breast did not differ between breast cancer and control women, 920 pmol/kg and 890 pmol/kg, respectively. In breast cancer patients but not in the controls, breast adipose tissue estrone levels correlated positively with the serum estrone concentration. In conclusion, the new method provides a reliable means to measure estrone concentrations in adipose tissue in postmenopausal women.

Animal Models in Endometriosis Research

The initiation of endometriosis in women is difficult to investigate, because there is usually a delay of several years from the onset of lesion development to the clinical diagnosis. Animal models of endometriosis, on the other hand, provide an important contribution to the investigation of the disease pathogenesis and the efficacy of therapeutic intervention strategies.

Vitreous estrogen levels in patients with an idiopathic macular hole

Purpose

Estrogen, a female hormone, activates collagenase and might be associated with the pathogenesis of vitreoretinal collagen fiber disease. The purpose of the present study was to investigate the vitreous levels of estrone (E1) and estradiol (E2) in subjects with an idiopathic macular hole (IMH).

Methods

Vitreous samples were obtained from ten female patients with an IMH and from nine female patients with other retinal diseases (six with rhegmatogenous retinal detachment and three with age-related macular degeneration) as a control at the time of vitreous surgery. E1 and E2 levels in the vitreous samples were then determined using the Coat-A-Count^® Estradiol Radioimmunoassay (RIA) Kit and the DSL-70 Estrone RIA Kit, respectively.

Results

The mean vitreous levels of E1 and E2 in the subjects with IMH were 1.83±2.00 pg/mL and 7.03±2.97 pg/mL, respectively, whereas in the control subjects they were 2.42±1.25 pg/mL and 4.90±2.90 pg/mL, respectively. Thus, the vitreous E2 levels in the subjects with IMH were significantly higher than in the controls (P<0.05).

Conclusion

The findings of this study suggest that E2 might be associated with the pathogenesis of IMH, but further investigation is needed to elucidate that association.

Analysis of the rs10046 polymorphism of aromatase (CYP19) in premenopausal onset of human breast cancer

The CYP19 gene encodes aromatase, an enzyme catalyzing the conversion of androgens to estrogens. Studies analyzing associations between single nucleotide polymorphisms in CYP19 and breast cancer risk have shown inconsistent results. The rs10046 polymorphism is located in the 3′ untranslated region of the CYP19 gene, but the influence of this polymorphism on breast cancer risk is unclear. In this study, we investigated the impact of rs10046 SNP on breast cancer risk, age at onset and association with clinical characteristics in an Austrian population of 274 breast cancer patients and 253 controls. The results show that a significantly increased fraction of patients with the TT genotype of rs10046 develop breast cancer under the age of 50 (41.8% of TT patients, compared to 26.6% of C carriers; p = 0.018, Chi-square test). No rs10046 genotypes were significantly associated with increased breast cancer risk or patient characteristics other than age at onset. These results suggest that the rs10046 polymorphism in the CYP19 gene may have an effect on breast cancer susceptibility at an age under 50 in the investigated population.

Calcium and vitamin D supplementation and loss of bone mineral density in women undergoing breast cancer therapy

An unintended consequence of breast cancer therapies is an increased risk of osteoporosis due to accelerated bone loss. We conducted a systematic review of calcium and/or vitamin D (Ca±D) supplementation trials for maintaining bone mineral density (BMD) in women with breast cancer using the "before-after" data from the Ca±D supplemented comparison group of trials evaluating the effect of drugs such as bisphosphonates on BMD. Whether Ca±D supplements increase BMD in women undergoing breast cancer therapy has never been tested against an unsupplemented control group. However, results from 16 trials indicate that the Ca±D doses tested (500-1500mg calcium; 200-1000IU vitamin D) were inadequate to prevent BMD loss in these women. Cardiovascular disease is the main cause of mortality in women with breast cancer. Because calcium supplements may increase cardiovascular disease risk, future trials should evaluate the safety and efficacy of Ca±D supplementation in women undergoing breast cancer therapy.

Extremes of an aromatase index predict increased 25-year risk of cardiovascular mortality in older women

BACKGROUND

Peripheral conversion of androgens to oestrogens via aromatase is the primary source of oestrogen in postmenopausal women and may play a role in cardiovascular health.

DESIGN

Prospective. PARTICIPANTS, MEASUREMENTS: The association of an index of aromatase activity (AROM), the serum oestrone-to-androstenedione ratio, with 25-year cardiovascular disease (CVD) mortality was examined in 819 postmenopausal non-oestrogen using women (mean age at baseline = 72).

RESULTS

Overall, 247 deaths were attributed to CVD. The median AROM value was 60 (95% range 17-129). AROM was positively correlated with age (r = 0·28) and body mass index (BMI) (r = 0·22) (P < 0·001). The age-adjusted risk for CVD mortality was significantly elevated for women in the lowest (HR = 2·01, 95% CI 1·31-3·12) and highest (HR = 1·51, 95%CI 1·02-2·22) quintiles of AROM, compared with the middle quintile. This U-shaped association persisted after additional adjustment for BMI, waist-to-hip ratio, exercise, smoking, alcohol use and traditional CVD risk factor covariates. There was a significant interaction of AROM and BMI (P = 0·001), such that high AROM was associated with a 63% reduction in risk of CVD death for women with low BMI (<22 kg/m(2) ), but with 2·1- to 2·5-fold increased risk in women with mid-range (22-<25 kg/m(2) ) and high (≥25 kg/m(2) ) BMI. Oestradiol did not influence AROM associations and was not independently related to CVD death.

CONCLUSIONS

These results suggest that aromatase is a novel endocrine factor predictive of CVD mortality among postmenopausal women. If confirmed, additional studies are needed to determine whether extremes of aromatase reflect genetic influences or underlying disease processes.

Influence of juvenile housing conditions on the ventilatory, thermoregulatory, and endocrine responses to hypoxia of adult male rats

“Extreme” housing conditions, such as isolation (single housing) or crowding, are stressful for rats, and their deleterious impact on behavior is well documented. To determine whether more subtle variations in housing can affect animal physiology, the present study tested the hypothesis that the hypoxic ventilatory response (HVR) of adult male rats housed in pairs during the juvenile period (postnatal day 21 to adulthood) does not differ from that of animals housed in triads. Because neonatal stress augments the neuroendocrine responsiveness to stress and HVR, experiments were performed both on “control” (undisturbed) animals and rats subjected to neonatal maternal separation (NMS; 3 h/day, postnatal days 3–12). At adulthood, ventilatory activity was measured by whole body plethysmography under normoxic and hypoxic conditions (inspired fraction of O2 = 0.12; 20 min). The ventilatory and body temperature responses to hypoxia of rats raised in triads were less than those of rats housed in pairs. For the HVR, however, the attenuation induced by triad housing was more important in NMS rats. Triad housing decreased “basal” plasma corticosterone, but increased estradiol and testosterone levels. Much like the HVR, housing-related decrease in corticosterone level was greater in NMS than control rats. We conclude that modest changes in housing conditions (pairs vs. triads) during the juvenile period can influence basic homeostatic functions, such as temperature, endocrine, and respiratory regulation. Housing conditions can influence (even eliminate) the manifestations of respiratory plasticity subsequent to deleterious neonatal treatments. Differences in neuroendocrine function likely contribute to these effects.

Cellular and molecular actions displayed by estrone on vascular endothelium

In this work we provide evidence that estrone "per se" modulates cellular endothelial growth and survival, events that play key roles in the development of vascular disease. Moreover, under oxidative stress conditions the hormone prevented apoptosis triggered by hydrogen peroxide. Although estrone did not affect E-selectin and VCAM-1 mRNAs synthesis, the hormone prevented the expression of these adhesion molecules induced by the proinflammatory agent LPS. The steroid partially attenuated leukocyte adhesion not only under basal conditions but also in the presence of LPS. Using ICI182780 compound as estrogen receptor antagonist, and PD98059 as MAPK inhibitor we obtained evidence that the mitogenic action of estrone involved the participation of ER and MAPK transduction pathway activation. The presence of estradiol impaired the effect of estrone on cell proliferation and vasoactive production. These results suggest that estrone exhibits a remarkable biological action on endothelial cells, modulating vasoactive production, proliferation, apoptosis, and cell adhesion events.

Aromatase inhibition: a potential target for the management of recurrent or metastatic endometrial cancer by letrozole: more questions than answers?

INTRODUCTION

Endometrial cancer generally presents as early and resectable disease, but about 20% of patients present with either incurable or recurrent/metastatic disease. Patients with good performance status will be treated with hormonal agents, including progestins and tamoxifen, followed by cytotoxic chemotherapy. The options are restricted to hormonal agents for those with multiple comorbidities and older age. Therefore, there is a need to identify novel hormonal agents and other targeted therapeutics with improved therapeutic window in this setting.

AREA COVERED

Clinical trials of letrozole in localized and metastatic settings are reviewed. In the localized setting, limited by the small sample size, preliminary and conflicting clinical activities were observed. Despite the selection of Type I endometrial cancer, which is more estrogen-dependent for its growth, modest clinical activity was observed in the metastatic setting. Thus far, no biomarkers for efficacy have been identified.

EXPERT OPINION

Further understanding of the relevance of aromatase and estrogen receptor and their interplay with other growth pathways will be necessary to guide further development of letrozole. It is premature to declare letrozole a therapeutic option in recurrent/metastatic endometrial cancer.

The role of estrogen deficiency in skin ageing and wound healing

The links between hormonal signalling and lifespan have been well documented in a range of model organisms. For example, in C. elegans or D. melanogaster, lifespan can be modulated by ablating germline cells, or manipulating reproductive history or pregnenolone signalling. In mammalian systems, however, hormonal contribution to longevity is less well understood. With increasing age human steroid hormone profiles change substantially, particularly following menopause in women. This article reviews recent links between steroid sex hormones and ageing, with special emphasis on the skin and wound repair. Estrogen, which substantially decreases with advancing age in both males and females, protects against multiple aspects of cellular ageing in rodent models, including oxidative damage, telomere shortening and cellular senescence. Estrogen's effects are particularly pronounced in the skin where cutaneous changes post-menopause are well documented, and can be partially reversed by classical Hormone Replacement Therapy (HRT). Our research shows that while chronological ageing has clear effects on skin wound healing, falling estrogen levels are the principle mediator of these effects. Thus, both HRT and topical estrogen replacement substantially accelerate healing in elderly humans, but are associated with unwanted deleterious effects, particularly cancer promotion. In fact, much current research effort is being invested in exploring the therapeutic potential of estrogen signalling manipulation to reverse age-associated pathology in peripheral tissues. In the case of the skin the differential targeting of estrogen receptors to promote healing in aged subjects is a real therapeutic possibility.

Effect of long-term topical application of dehydroepiandrosterone (DHEA) and oral estrogens on morphology, cell proliferation, procollagen A1 and androgen receptor levels in rat skin

BACKGROUND

After cessation of estrogen secretion by the ovaries at menopause, all estrogens and almost all androgens acting in the skin of postmenopausal women are synthesized locally from dehydroepiandrosterone (DHEA), a prohormone of adrenal origin that progressively declines with age.

OBJECTIVE

To better understand the effects of DHEA on the skin, ovariectomized (OVX) rats were treated for 9 months with local topical application of DHEA compared with oral conjugated equine estrogens.

MATERIALS AND METHODS

Morphological evaluation, immunohistochemistry for androgen receptor (AR) and Cdc47 proliferation marker, and in situ hybridization for procollagen A1 were performed on dorsal skin.

RESULTS

Local topical DHEA application increased the thickness of the granular cell layer and total epidermis in OVX animals, whereas systemic estrogens had no significant effect. Although DHEA did not affect total dermal thickness, a 190% increase in dermal procollagen A1 mRNA was observed. Moreover, DHEA treatment decreased hypodermal thickness by 47% and increased skin muscle thickness by 58%. In the epidermis, DHEA induced a non-significant increase in cell proliferation, whereas AR labeling was increased in both the epidermis and dermis by DHEA.

CONCLUSIONS

Although estrogens did not significantly modify any of the above-mentioned parameters, the androgenic action of DHEA induced significant changes in all skin layers, without any sign of toxicity or lack of tolerance to DHEA after a 9-month local application of 4% (80 mg/kg) DHEA on the skin.

Endometriosis in Italy: from cost estimates to new medical treatment

Endometriosis is defined as the presence of endometrial-like tissue outside the uterus, which induced a chronic inflammatory reaction. The data collected from Italy showed that around 3 million women are affected by endoemtriosis and the condition was predominantly found in women of reproductive age (50% of women were in the 29-39 age range), only 25% of women were asymptomatic. The associated symptoms can create an impact in general physical, mental, and social well-being. Endometriosis is associated with severe dysmenorrhea, deep dyspareunia, chronic pelvic pain, ovulation pain, cyclical, or perimenstrual symptoms, with or without abnormal bleeding, infertility, and chronic fatigue. The annual cost for hospital admission can be estimated to be in a total around 54 million euros. The average time for right diagnosis is around 9 years still today and it follows a long and expensive diagnostic search. Therapies can be useful to relieve and sometimes solve the symptoms, encourage fertility, eliminate endometrial lesions, and restore the anatomy of the pelvis. For medical therapy, several different preparations (oral contraceptives, progestogenics, gestrinone, danazol, and GnRHa) and new options (GnRH antagonists, aromatase inhibitors, estrogen receptor beta agoinist, progesterone receptor modulators, angiogenesis inhibitors, and COX-2 selective inhibitors) are available.

Alternative use of multiple exons 1 of aromatase gene in cancerous and normal breast tissues from women over the age of 80 years

INTRODUCTION

Peripherally localized aromatase, which converts circulating androgens into estrogens, is important in the pathogenesis of postmenopausal breast carcinomas. We have previously shown that aromatase mRNA levels are higher in elderly breast carcinomas (EldCa) than breast carcinomas of the control group (ContCa) or normal breast tissues. Aromatase expression has been reported to be regulated through the alternative use of multiple exons 1 (exons 1a-1f and so on); however, the preferential usage of exons 1 in elderly breast tissue has never been systematically examined. In order to properly treat and protect against EldCa, the regulation mechanism of aromatase expression in elderly breast tissues should be elucidated. The aim of the present study is to elucidate whether there are any specific patterns in use of multiple exons 1 in elderly breast tissue.

METHODS

Usage of multiple exons 1 of the aromatase gene and mRNA levels of aromatase were examined by reverse transcription-polymerase chain reaction analysis in breast tissues of 38 elderly patients with breast cancer (age 80-99), and the results were compared with those in 35 patients of the control group (age 37-70). One-factor analysis of variance and the Scheffé test were used for the comparison of aromatase mRNA levels. Patterns of preferential utilization of multiple exons 1 of the aromatase gene were compared by chi2 test for independence or Fisher exact test for independence using a contingency table.

RESULTS

Exon 1d was utilized much more frequently in elderly tissue than in the control group irrespective of cancerous or normal tissue (EldCa, 36/38, 95% versus ContCa, 7/35, 20%, P < 0.0001; normal tissue of the elderly, EldNorm, 30/34, 88% versus normal tissue of controls, ContNorm, 2/29, 7%, P < 0.0001). Twenty EldCa (53%) and 12 EldNorm (35%) used both exons 1c and 1d; however, their dominance was reversed (EldCa, all 1d > 1c; EldNorm, all 1c > 1d).

CONCLUSIONS

Elderly breast tissues exhibited specific patterns in use of multiple exons 1, which at least partly explained the higher aromatase levels in EldCa. The mechanisms of how these specific patterns occur during aging and carcinogenesis should be further examined.

Association between bone mineral density, lean mass, and fat mass among healthy middle-aged premenopausal women: a cross-sectional study in southern Sri Lanka

Associations between lean mass, fat mass, and bone mass have been reported earlier; however, most of those studies have been done in Caucasian populations, and data from Asian countries, especially those in South Asia, are limited. We examined the associations between lean mass, fat mass, bone mineral density (BMD), and bone mineral content (BMC), determined by dual-energy X-ray absorptiometry technology, in a group of healthy, middle-aged, premenopausal female volunteers. The mean (SD) age of the women (n = 106) was 42.1 (6.1) years and the mean (SD) body mass index was 24.3 (3.6) kg/m(2). Total body BMD, total body BMC, and BMD in total spine, total hip, and femoral neck showed statistically significant partial correlations (adjusted for age) with total fat mass (r = 0.19-0.43, P < 0.05) and lean body mass (r = 0.28-0.54, P < 0.05). Truncal fat mass correlated positively with total body BMC and BMD at total hip and femoral neck (r = 0.33-0.40, P < 0.001). When a stepwise regression model was fitted, lean mass remained the strongest predictor of total body BMD, total body BMC, and total spine BMD (regression coefficients = 0.004-0.008 g/cm(2) per 1-kg change in lean mass, P < 0.001). Similarly, crude BMD and BMC increased across the tertiles of lean mass (P trend < 0.05). We show that lean mass is the strongest predictor of total body BMC and BMD at different sites, although positive correlations with fat mass also exist.

Steroidogenic enzyme and key decidualization marker dysregulation in endometrial stromal cells from women with versus without endometriosis

Identification of mechanisms underlying endometriosis pathogenesis will facilitate understanding and treatment of infertility and pain associated with this disorder. Herein, we investigated the expression of steroidogenic pathway enzymes and key decidualization biomarkers in endometrial tissue and in eutopic endometrial stromal fibroblasts (hESFs) from women with vs. those without endometriosis, and subsequently treated in vitro with 8-bromo-cAMP (8-Br-cAMP) or progesterone (P4). Real-time quantitative PCR, immunohistochemistry, ELISA, and radiometric aromatase activity assay were used. The results demonstrate significantly increased (14.5-fold; P=0.037) expression of aromatase in eutopic endometrium of women with disease. In 8-Br-cAMP-treated hESF from eutopic endometrium of women with endometriosis, the balance in estradiol (E2) and P4 biosynthetic and metabolizing enzymes is disturbed (decreased HSD3B1 and HSD17B2, and increased HSD17B1 and aromatase), with the equilibrium being shifted towards an E2-enriched milieu. However, hESF from the same group of women treated with P4 did not demonstrate such responsiveness. Lower expression of IGFBP1 and prolactin mRNA and protein was observed in hESF from women with vs. those without endometriosis in response to 8-Br-cAMP, but not P4, suggesting a blunted response of these decidual biomarkers to activation of the PKA pathway in eutopic endometrium in women with disease. The dichotomy of 8-Br-cAMP regulation of select steroidogenic enzymes leading to an enriched E2 milieu within the endometrium and a blunted response of decidual biomarkers to this decidualizing agent of hESF from women with endometriosis suggests resistance to full decidualization of the stromal fibroblasts and mechanisms underlying implantation failure and the pathophysiology of this disorder.

Dietary genistein negates the inhibitory effect of letrozole on the growth of aromatase-expressing estrogen-dependent human breast cancer cells (MCF-7Ca) in vivo

Genistein (GEN), a soy isoflavone, stimulates growth of estrogen-dependent human tumor cells (MCF-7) in a preclinical mouse model for postmenopausal breast cancer. Antiestrogens and aromatase inhibitors are frontline therapies for estrogen-dependent breast cancer. We have demonstrated that dietary GEN can negate the inhibitory effect of tamoxifen. In this study, we evaluated the interaction of dietary GEN (at 250-1000 p.p.m. in the American Institute of Nutrition 93 growth diet) and an aromatase inhibitor, letrozole (LET), on the growth of tumors in an aromatase-expressing breast cancer xenograft model (MCF-7Ca) in the presence and absence of the substrate androstenedione (AD). Dietary GEN (250 and 500 p.p.m.) or implanted AD stimulated MCF-7Ca tumor growth. Implanted LET inhibited AD-stimulated MCF-7Ca tumor growth. In the presence of AD and LET, dietary GEN (250, 500 and 1000 p.p.m.) reversed the inhibitory effect of LET in a dose-dependent manner. Uterine wet weight, plasma estradiol (E(2)) levels (enzyme-linked immunosorbent assay) and total plasma GEN and LET levels (liquid chromatography-electrospray/tandem mass spectrometry) were measured. Ki-67 (cellular proliferation), aromatase and pS2 protein expression in tumors were evaluated using immunohistochemical (IHC) analysis. In conclusion, dietary GEN increased the growth of MCF-7Ca tumors implanted in ovariectomized mice and could also negate the inhibitory effect of LET on MCF-7Ca tumor growth. These findings are significant because tumors, which express aromatase and synthesize estrogen, are good candidates for aromatase therapy dietary and GEN can reverse the inhibitory effect of LET on tumor growth and adversely impact breast cancer therapy. Caution is warranted for consumption of dietary GEN by postmenopausal women with estrogen-dependent breast cancer taking LET treatment.

Role of melatonin in the epigenetic regulation of breast cancer

The oncostatic properties of melatonin as they directly or indirectly involve epigenetic mechanisms of cancer are reviewed with a special focus on breast cancer. Five lines of evidence suggest that melatonin works via epigenetic processes: (1) melatonin influences transcriptional activity of nuclear receptors (ERalpha, GR and RAR) involved in the regulation of breast cancer cell growth; (2) melatonin down-regulates the expression of genes responsible for the local synthesis or activation of estrogens including aromatase, an effect which may be mediated by methylation of the CYP19 gene or deacetylation of CYP19 histones; (3) melatonin inhibits telomerase activity and expression induced by either natural estrogens or xenoestrogens; (4) melatonin modulates the cell cycle through the inhibition of cyclin D1 expression; (5) melatonin influences circadian rhythm disturbances dependent on alterations of the light/dark cycle (i.e., light at night) with the subsequent deregulation of PER2 which acts as a tumor suppressor gene.

Leptin concentrations, leptin receptor polymorphisms, and colorectal adenoma risk

Obesity has been shown to be associated with an increased risk of both colorectal cancer and adenomatous polyps. One mechanism underlying this relationship may involve the growth-promoting effects of the circulating hormones associated with obesity, such as leptin. We conducted a gastroenterology clinic-based, case-control study to evaluate the relationship between circulating leptin concentrations and colorectal adenoma risk; in addition, we evaluated the relationship between leptin receptor polymorphisms and adenoma risk. Individuals with adenomas (n = 157) and colonoscopy-negative controls (n = 191), who had a clinically indicated colonoscopy, were recruited from a large health maintenance organization in the Seattle metropolitan area from 1999 to 2003. Odds ratios and 95% confidence intervals were obtained using logistic regression, adjusting for age at diagnosis, body mass index, family history of colorectal cancer, smoking history, nonsteroidal anti-inflammatory drug use, physical activity, and, among women, menopausal status and postmenopausal hormone use. Among men, those in the highest tertile of leptin concentrations had a 3.3-fold (95% confidence interval, 1.2-8.7) increased adenoma risk compared with those in the lowest tertile (P trend = 0.01). There were no associations between leptin concentrations and adenoma risk in women. There were no associations of leptin receptor genotypes or haplotypes and adenoma risk. The results of this study suggest that, in men, leptin may be associated with risk of colorectal adenomas.

Absence of the proapoptotic Bax protein extends fertility and alleviates age-related health complications in female mice

The menopausal transition in human females, which is driven by a loss of cyclic ovarian function, occurs around age 50 and is thought to underlie the emergence of an array of health problems in aging women. Although mice do not undergo a true menopause, female mice exhibit ovarian failure long before death because of chronological age and subsequently develop many of the same age-associated health complications observed in postmenopausal women. Here we show in mice that inactivation of the proapoptotic Bax gene, which sustains ovarian lifespan into advanced age, extends fertile potential and minimizes many age-related health problems, including bone and muscle loss, excess fat deposition, alopecia, cataracts, deafness, increased anxiety, and selective attention deficit. Further, ovariectomy studies show that the health benefits gained by aged females from Bax deficiency reflect a complex interplay between ovary-dependent and -independent pathways. Importantly, and contrary to popular belief, prolongation of ovarian function into advanced age by Bax deficiency did not lead to an increase in tumor incidence. Thus, the development of methods for postponing ovarian failure at menopause may represent an attractive option for improving the quality of life in aging females.

Signal transduction pathways involved in non-genomic action of estrone on vascular tissue

Previously we demonstrated that estrone non-genomically regulates rat aortic NOS and COX activity and that this effect depends on ovarian activity. The purpose of the present study was to characterize this effect and investigate the participation of phospholipase C and phophatidylinositol-3-kinase system in the intracellular transduction pathway involved in the response. Using aortic strips isolated from female fertile rats we showed that estrone stimulate nitric oxide synthase and cyclooxygenase in a short time interval (5-20 min), and that NO production was dependent in part on PGI2 production since 1 microM indomethacin significantly reduced this free radical production. Injection of 17-beta-estradiol to ovariectomized rats restored tissue capacity to rapidly increase NO production in response to "in vitro" treatment with 1 nM estrone. We also demonstrated that in aortic strips isolated from intact animals estrone elicited a rapid phospholipase C activation, inducing a biphasic increase in diacylglycerol generation (peaking at 45 s and 5 min). The presence of protein kinase C inhibitor chelerythrine did not prevent the increase of NO released in response to hormone treatment. We proved that PI3K-Akt system does not mediate NOS and COX activation. However, PLC activation was dependent on PI3K since presence of LY 294002 in the incubation medium abolished estrone-induced DAG increment. We concluded that, estrone rapid action on vascular tissue involves a cross talk between NOS and COX system, and the activation of PLC/DAG/PKC transduction pathways.

O6-Methylguanine-DNA Methyltransferase Leu84Phe and Ile143Val Polymorphisms and Risk of Colorectal Cancer in the Nurses’ Health Study and Physicians’ Health Study (United States)

OBJECTIVE

O6-methylguanine-DNA methyltransferase (MGMT) removes mutagenic adducts from the O6-position of guanine in DNA. Unrepaired O6-methylguanines result in G:C to A:T transitions in mutated K-ras and p53 in colorectal tumors. Two non-synonymous MGMT coding region variants, Leu84Phe and Ile143Val, lie in close proximity to the reactive 145Cys residue and to a conserved estrogen receptor interacting helix.

METHODS

We assessed the association between the MGMT Leu84Phe and Ile143Val polymorphisms and risk of colorectal cancer in two nested case-control studies: one each in the Nurses' Health Study (NHS) and the Physicians' Health Study (PHS) cohorts.

RESULTS

Among 197 female cases and 2,500 controls from the NHS, the variant 143Val allele was significantly associated with reduced risk of colorectal cancer [odds ratio (OR) = 0.52, 95% confidence interval (CI) 0.33-0.80]. In women, statistically significant gene-environment interactions were found between the Leu84Phe polymorphism and alcohol intake (P = 0.03), BMI (P = 0.04) and postmenopausal hormone use (P = 0.03). The Leu84Phe and Ile143Val polymorphisms were not significantly associated with risk of colorectal cancer among 271 male cases and 451 controls from the PHS.

CONCLUSIONS

Our results suggest that the common Leu84Phe and Ile143Val polymorphisms in MGMT influence risk of colorectal cancer in women possibly through modulating estrogen receptor-dependent transcriptional activation, which has previously been shown to occur in response to DNA alkylation damage.

Aromatase and the breast: regulation and clinical aspects

The aromatase enzyme is unique to the pathway of oestrogen biosynthesis and converts androgen precursors into oestrogens, major stimulatory factors for breast cancer proliferation. Although there is only a single gene for aromatase and a single protein for the enzyme, transcriptional control is complex using different promoters which are in part tissue-specific. These generate different mRNA transcripts that vary in the presence/absence of individual untranslated exon 1s. In breast cancers, species vary between individual tumours, types I.3 and I.4 being the major species in some tumours but type II predominates in the majority. Since the type II promoter is regulated by prostaglandins/cyclic AMP, agents signalling through these systems seem largely responsible for local regulation of intratumoural oestrogen biosynthesis. Autocrine production of these factors would account for the high activity in breast cancers and paracrine secretion for the raised activity in breast fat associated with the local presence of cancer. Given the central role of oestrogen in normal development and pathological processes, there has been great interest in controlling aromatase activity by the use of specific inhibitors. Clinically, this is particularly evident in the management of postmenopausal women with breast cancer.

Aromatase and cyclooxygenase-2 expression in endometrial polyps during the menstrual cycle

OBJECTIVES

To study the changes in aromatase, Ki-67 and cyclooxygenase-2 (COX-2) expression during the menstrual cycle in both endometrial polyps and normal endometria.

PATIENTS AND METHODS

Paraffin-embedded tissue samples from 118 premenopausal patients were submitted to immunohistochemistry for measurement of aromatase, COX-2 and Ki-67 expression. Fifty cases of endometrial polyps and 68 cases of disease-free endometrium were included.

RESULTS

The presence of aromatase expression was significantly higher in endometrial polyps than in disease-free endometria. On the other hand, changes in COX-2 and Ki-67 expression followed a similar pattern during the menstrual cycle in both groups, expression peaking during the proliferative phase and falling during the late luteal phase.

CONCLUSION

A significantly higher proportion of endometrial polyps express aromatase compared with disease-free endometrium; however, no correlation was found between aromatase expression and changes in either Ki-67 or COX-2 expression during the menstrual cycle.

Melatonin inhibits the growth of DMBA-induced mammary tumors by decreasing the local biosynthesis of estrogens through the modulation of aromatase activity

Melatonin inhibits the growth of breast cancer cells by interacting with estrogen-responsive pathways, thus behaving as an antiestrogenic hormone. Recently, we described that melatonin reduces aromatase expression and activity in MCF-7 human breast cancer cells, thus modulating the local estrogen biosynthesis. To investigate the in vivo aromatase-inhibitory properties of melatonin in our current study, this indoleamine was administered to rats bearing DMBA-induced mammary tumors, ovariectomized (ovx) and treated with testosterone. In these castrated animals, the growth of the estrogen-sensitive mammary tumors depends on the local aromatization of testosterone to estrogens. Ovariectomy significantly reduced the size of the tumors while the administration of testosterone to ovx animals stimulated tumor growth, an effect that was suppressed by administration of melatonin or the aromatase inhibitor aminoglutethimide. Uterine weight of ovx rats, which depends on the local synthesis of estrogens, was increased by testosterone, except in those animals that were also treated with melatonin or aminoglutethimide. The growth-stimulatory effects of testosterone on the uterus and tumors depend exclusively on locally formed estrogens, since no changes in serum estradiol were appreciated in testosterone-treated rats. Tumors from animals treated with melatonin had lower microsomal aromatase activity than tumors of animals from other groups, and incubation with melatonin decreased the aromatase activity of microsomal fractions of tumors. Animals treated with melatonin had the same survival probability as the castrated animals and significantly higher survival probability than the uncastrated. We conclude that melatonin could exert its antitumoral effects on hormone-dependent mammary tumors by inhibiting the aromatase activity of the tumoral tissue.

Interrelationships of serum estradiol, estrone, and estrone sulfate, adiposity, biochemical bone markers, and leptin in post-menopausal women

OBJECTIVE

The aim of this study was to examine the relationships between endogenous estrogens and adiposity, bone markers, and leptin in post-menopausal (PM) women.

DESIGN

Seventy-three post-menopausal (PM) women participated in a clinical correlational study. Weight, height, waist-hip ratio, fasted morning serum and first morning voided urine samples were obtained to compare body mass index (BMI), waist-hip ratio, endogenous estrogens, leptin, and bone markers. Serum estradiol, estrone (E1), estrone sulfate (E1S), leptin, osteocalcin, and urinary deoxypyridinoline (Dpd) were determined.

RESULTS

Significant positive relationships were found between BMI and estradiol, E1, and E1S (r = 0.52, 0.38, and 0.29; P < or = 0.001, 0.001, and 0.013 respectively). Significant relationships between leptin and estrogens were revealed, but were not significant when BMI was used as a covariate. Although many subjects revealed elevated bone marker levels, no correlation between estrogens or BMI and bone markers (Dpd and osteocalcin) was found.

CONCLUSIONS

There are significant positive correlations between estrogens and BMI in PM women. Increasing levels of estradiol, E1, and E1S with increasing BMI may be an indicator of adiposity, but are without effect as a stimulatory factor on leptin production. Waist-hip ratio did not significantly affect leptin concentrations when accounting for BMI. Due to assay sensitivity in the present study, data represent a more precise representation of these relationships. The lack of correlation between estrogens and bone marker levels may have been due to low estrogen levels in PM women.

Estrogen selectively promotes the differentiation of dendritic cells with characteristics of Langerhans cells

The steroid hormone estrogen regulates the differentiation, survival, or function of diverse immune cells. Previously, we found that physiological amounts of 17beta-estradiol act via estrogen receptors (ER) to promote the GM-CSF-mediated differentiation of dendritic cells (DC) from murine bone marrow progenitors in ex vivo cultures. Of the two major subsets of CD11c(+) DC that develop in these cultures, estrogen is preferentially required for the differentiation of a CD11b(int)Ly6C(-) population, although it also promotes increased numbers of a CD11b(high)Ly6C(+) population. Although both DC subsets express ERalpha, only the CD11b(high)Ly6C(+) DC express ERbeta, perhaps providing a foundation for the differential regulation of these two DC types by estrogen. The two DC populations exhibit distinct phenotypes in terms of capacity for costimulatory molecule and MHC expression, and Ag internalization, which predict functional differences. The CD11b(int)Ly6C(-) population shows the greatest increase in MHC and CD86 expression after LPS activation. Most notably, the estrogen-dependent CD11b(int)Ly6C(-) DC express langerin (CD207) and contain Birbeck granules characteristic of Langerhans cells. These data show that estrogen promotes a DC population with the unique features of epidermal Langerhans cells and suggest that differentiation of Langerhans cells in vivo will be dependent upon local estrogen levels and ER-mediated signaling events in skin.

Melatonin enhances the inhibitory effect of aminoglutethimide on aromatase activity in MCF-7 human breast cancer cells

The inhibition of the aromatase-induced intratumoral estrogen synthesis is one of the main anticancer pharmacological strategies. The aim of this paper was to study if a melatonin pretreatment prior to aminoglutethimide increases the efficiency of the aromatase inhibitor used in treating breast cancer. Aminoglutethimide (100 microM) and melatonin (1 nM) significantly decreased cellular aromatase activity in unpretreated MCF-7 cells. A sequential regimen of melatonin (1 nM) followed 24 h later by aminoglutethimide (100 microM) induced a significantly higher decrease in MCF-7 cell aromatase activity to below the values obtained in unpretreated cells. Melatonin treatment inhibited aromatase mRNA expression in unpretreated cells and a sequential treatment of cells with melatonin followed by aminoglutethimide induced a significant inhibition in the aromatase mRNA expression as compared to cells exposed to the same doses of aminoglutethimide, but without melatonin pretreatment. The present study demonstrates that a treatment with melatonin followed by aminoglutethimide is the most effective way of reducing the aromatase activity in the MCF-7 cell line. The aminoglutethimide inhibitory effect is more potent when MCF-7 cells are pre-exposed to melatonin. Our results suggest that melatonin pretreatment increases the reduction of the aromatase activity of cells exposed to aminoglutethimide as a result of the decrease in the aromatase mRNA expression. The findings presented here point to melatonin pretreatment as a novel and interesting means to increase the efficacy of competitive aromatase inhibitors used in treating breast cancer.

CYP19 (aromatase) haplotypes and endometrial cancer risk

Endogenous estrogen exposure is an important determinant of endometrial cancer risk. Aromatase, encoded by CYP19, catalyzes the aromatization of androstenedione and testosterone to estrone and estradiol, respectively. Several common genetic polymorphisms in CYP19 have been identified, including a TCT insertion/deletion and a (TTTA)(n) repeat polymorphism in intron IV as well as a 3'UTR C/T polymorphism. We evaluated these 3 polymorphisms plus an additional 9 noncoding polymorphisms as individual genotypes and predicted haplotypes as risk factors for endometrial cancer using a nested case-control study design. Invasive endometrial cancer cases (n = 222) and matched controls (n = 666) were identified among participants in the Nurses' Health Study who had provided a blood sample in 1989-1990 (n = 32,826). We estimated haplotypes from unphased genotype data spanning > 123 kb of CYP19. Six haplotypes constructed from 10 SNPs were estimated with a frequency > or = 5%. The highest prevalence haplotype (33% among cases, 28% among controls) was significantly associated with endometrial cancer risk (p = 0.03). Loci with variant alleles that comprise the risk haplotype were independently associated with endometrial cancer, with relative risk estimates ranging from 1.68 (95% CI 1.13-2.48) to 2.07 (95% CI 1.33-3.23), comparing variant allele carriers to wild-type homozygotes. We observed significant interactions between menopausal status and 2 of the high-risk loci (p = 0.03 and p < 0.01), with > 2-fold increased risk for variant allele carriers who were postmenopausal but no association between genotype and endometrial cancer among premenopausal women. We evaluated associations between CYP19 haplotypes and plasma steroid hormone levels. The haplotype associated with endometrial cancer risk is also significantly associated with the ratios of estrone to androstenedione and estradiol to testosterone, the products and substrates of the enzyme aromatase, encoded by CYP19. Our data suggest that there is a high-frequency CYP19 haplotype related to higher estrogen to androgen ratios and increased risk of endometrial cancer and that this association may primarily pertain to postmenopausal women.

Novel action of estrone on vascular tissue: regulation of NOS and COX activity

The hypothesis tested in the present work is that estrone non-genomically regulates aortic nitric oxide synthase (NOS) and cyclooxygenase (COX) activities in female rats, and that such regulation depends on ovarian function. We found that physiological concentrations of estrone (E(1)) (0.1-10nM) significantly increased nitric oxide (NO) production (133 and 163% above control). The stimulatory action of E(1) on NOS activity was independent of calcium influx since the increase in NO elicited by the hormone was not affected by EGTA or verapamil. When COX activity was measured, we observed that estrone enhanced thromboxane (TXB(2)) production and prostacyclin (PGI(2)) release, but not prostaglandin (PGF(2), PGD(2), and PGE(2)) synthesis. Finally we demonstrated that the hormonal effect on NOS activity was not detected in rat aortic strips (RAS) isolated from animals deprived of ovarian activity (FR(-)) or ovariectomized rats (OVX). These results suggest that estrone exerts a direct, non-genomic action on rat aortic metabolism, which involves NOS and COX activation and depends on ovarian activity.