A physiologic role for testosterone in limiting estrogenic stimulation of the breast

Effect of testosterone therapy on breast tissue composition and mammographic breast density in trans masculine individuals

BACKGROUND

The effect of gender-affirming testosterone therapy (TT) on breast cancer risk is unclear. This study investigated the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs).

METHODS

Of the 444 TMIs who underwent chest-contouring surgeries between 2013 and 2019, breast tissue composition was assessed in 425 TMIs by the pathologists (categories of lobular atrophy and stromal composition) and using our automated deep-learning algorithm (% epithelium, % fibrous stroma, and % fat). Forty-two out of 444 TMIs had mammography prior to surgery and their breast tissue density was read by a radiologist. Mammography digital files, available for 25/42 TMIs, were analyzed using the LIBRA software to obtain percent density, absolute dense area, and absolute non-dense area. Linear regression was used to describe the associations between duration of TT use and breast tissue composition or breast tissue density measures, while adjusting for potential confounders. Analyses stratified by body mass index were also conducted.

RESULTS

Longer duration of TT use was associated with increasing degrees of lobular atrophy (p < 0.001) but not fibrous content (p = 0.82). Every 6 months of TT was associated with decreasing amounts of epithelium (exp(β) = 0.97, 95% CI 0.95,0.98, adj p = 0.005) and fibrous stroma (exp(β) = 0.99, 95% CI 0.98,1.00, adj p = 0.05), but not fat (exp(β) = 1.01, 95%CI 0.98,1.05, adj p = 0.39). The effect of TT on breast epithelium was attenuated in overweight/obese TMIs (exp(β) = 0.98, 95% CI 0.95,1.01, adj p = 0.14). When comparing TT users versus non-users, TT users had 28% less epithelium (exp(β) = 0.72, 95% CI 0.58,0.90, adj p = 0.003). There was no association between TT and radiologist's breast density assessment (p = 0.58) or LIBRA measurements (p > 0.05).

CONCLUSIONS

TT decreases breast epithelium, but this effect is attenuated in overweight/obese TMIs. TT has the potential to affect the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

Androgen receptor: Structure, signaling, function and potential drug discovery biomarker in different breast cancer subtypes

The Androgen Receptor (AR) is emerging as an important factor in the pathogenesis of breast cancer (BC), which is the most common malignancy worldwide. >70 % of AR expression in primary and metastatic breast tumors has been observed which suggests that AR may be a new marker and a potential therapeutic target among AR-positive BC patients. Biological insight into AR-positive breast cancer reveals that AR may cross-talk with several vital signaling pathways, including key molecules and receptors. Downstream signaling of AR might also affect many clinically important pathways that are emerging as clinical targets in BC. AR exhibits different behaviors depending on the breast cancer molecular subtype. Preliminary clinical research using AR-targeted drugs, which have already been FDA-approved for prostate cancer (PC), has given promising results for AR-positive breast cancer patients. However, since AR positivity's prognostic and predictive value remains uncertain, it is difficult to identify and stratify patients who would benefit from AR-targeted therapies alone. Thus, the need of the hour is to target the androgen receptor as a monotherapy or in combination with other conventional therapies which has proven to be an effective clinical strategy for the treatment of prostate cancer patients, and these therapeutic strategies are increasingly being investigated in breast cancer. Therefore, in this manuscript, we review the role of AR in various cellular processes that promote tumorigenesis and aggressiveness, in different subtypes of breast cancer, as well as discuss ongoing efforts to target AR for the more effective treatment and prevention of breast cancer.

The androgen receptor interacts with GATA3 to transcriptionally regulate a luminal epithelial cell phenotype in breast cancer

BACKGROUND

The androgen receptor (AR) is a tumor suppressor in estrogen receptor (ER) positive breast cancer, a role sustained in some ER negative breast cancers. Key factors dictating AR genomic activity in a breast context are largely unknown. Herein, we employ an unbiased chromatin immunoprecipitation-based proteomic technique to identify endogenous AR interacting co-regulatory proteins in ER positive and negative models of breast cancer to gain new insight into mechanisms of AR signaling in this disease.

RESULTS

The DNA-binding factor GATA3 is identified and validated as a novel AR interacting protein in breast cancer cells irrespective of ER status. AR activation by the natural ligand 5α-dihydrotestosterone (DHT) increases nuclear AR-GATA3 interactions, resulting in AR-dependent enrichment of GATA3 chromatin binding at a sub-set of genomic loci. Silencing GATA3 reduces but does not prevent AR DNA binding and transactivation of genes associated with AR/GATA3 co-occupied loci, indicating a co-regulatory role for GATA3 in AR signaling. DHT-induced AR/GATA3 binding coincides with upregulation of luminal differentiation genes, including EHF and KDM4B, established master regulators of a breast epithelial cell lineage. These findings are validated in a patient-derived xenograft model of breast cancer. Interaction between AR and GATA3 is also associated with AR-mediated growth inhibition in ER positive and ER negative breast cancer.

CONCLUSIONS

AR and GATA3 interact to transcriptionally regulate luminal epithelial cell differentiation in breast cancer regardless of ER status. This interaction facilitates the tumor suppressor function of AR and mechanistically explains why AR expression is associated with less proliferative, more differentiated breast tumors and better overall survival in breast cancer.

Effect of testosterone therapy on breast tissue composition and mammographic breast density in trans masculine individuals

Objective

Determine the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs).

Design

This is a cross-sectional study.

Setting

TMIs (n=444) underwent chest-contouring surgeries to treat their gender dysphoria between 2013 and 2019 at an urban medical center.

Participants

Of the 444 TMIs, 425 had pathology images analyzed by our deep-learning algorithm to extract breast tissue composition. A subset of 42/444 TMIs had mammography prior to surgery; mammography files were available for 25/42 TMIs and analyzed using a breast density software, LIBRA.

Main Outcomes and Measures

The first outcome was the association of duration of TT and breast tissue composition assessed by pathologists (categories of lobular atrophy and stromal composition) or by our algorithm (% epithelium, % fibrous stroma, and % fat). The second outcome is the association of TT and breast density as assessed by a radiologist (categorical variable) or by LIBRA (percent density, absolute dense area, and absolute non-dense area).

Results

Length of TT was associated with increasing degrees of lobular atrophy ( p <0.001) but not fibrous content ( p =0.821) when assessed by the pathologists. Every six months of TT was associated with decreased amounts of both epithelium (exp(β)=0.97, 95% CI 0.95-0.98, adj p =0.005) and stroma (exp(β)=0.99, 95% CI 0.98-1.00, adj p =0.051), but not fat (exp(β)=1.01, 95%CI 0.98-1.05, p =0.394) in fully adjusted models. There was no association between TT and radiologist's breast density assessment ( p =0.575) or LIBRA measurements ( p >0.05).

Conclusions

TT decreases breast epithelium and fibrous stroma, thus potentially reducing the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

Summary Box

Very little is known about the effect of gender-affirming testosterone therapy on cancer risks, such as breast cancer.Epidemiological studies had different conclusions about the association between testosterone and breast cancer in cisgender women (positive association) and trans masculine individuals (inverse association).More laboratory-based research are needed to understand the effect of testosterone on breast cancer risk in the understudied trans masculine population.Our study provides quantitative histological evidence to support prior epidemiological reports that testosterone may reduce breast cancer risk in trans masculine individuals.

Stranger Things: New Roles and Opportunities for Androgen Receptor in Oncology Beyond Prostate Cancer

The androgen receptor (AR) is one of the oldest therapeutic targets in oncology and continues to dominate the treatment landscape for advanced prostate cancer, where nearly all treatment regimens include some form of AR modulation. In this regard, AR remains the central driver of prostate cancer cell biology. Emerging preclinical and clinical data implicate key roles for AR in additional cancer types, thereby expanding the importance of this drug target beyond prostate cancer. In this mini-review, new roles for AR in other cancer types are discussed as well as their potential for treatment with AR-targeted agents. Our understanding of these additional functions for AR in oncology expand this receptor's potential as a therapeutic target and will help guide the development of new treatment approaches.

The Impact of Exogenous Testosterone on Breast Cancer Risk in Transmasculine Individuals

BACKGROUND

Exogenous testosterone is vital to gender-affirming therapy for transmasculine individuals. Testosterone may be implicated in breast cancer (BCa) because it can activate androgen and estrogen receptors. To further explore this risk, we performed a systematic review to investigate the impact of exogenous testosterone on BCa risk in transmasculine individuals.

METHODS

We searched PubMed/MEDLINE and Ovid/Embase for clinical and preclinical studies assessing BCa and testosterone therapy and screened 6125 articles independently. We ascertained level of evidence using a modified tool from Cook et al (Chest. 1992;102:305S-311S) and risk of bias using a modified Joanna Briggs Institute's Critical Appraisal Tool.

RESULTS

Seventy-six studies were included. Epidemiological data suggested that BCa incidence was higher in transmasculine individuals compared with cisgender men but lower compared with cisgender women. Histological studies of transmasculine breast tissue samples also demonstrated a low incidence of precancerous lesions. Interestingly, cases demonstrated that BCa occurred at a younger average age in transmasculine individuals and was predominantly hormone receptor positive. The mechanism for BCa in transmasculine individuals may be related to androgen receptor stimulation or conversion to estradiol. Serum studies reported varied estradiol levels associated with exogenous testosterone. Animal and in vitro studies demonstrated that testosterone was growth inhibitory but may induce proliferation at higher doses or with low estradiol levels.

CONCLUSIONS

Plastic surgeons play a critical role in providing gender-affirming care for transmasculine patients. The limited studies available suggest that this patient population has decreased risk for BCa when compared with cisgender women; however, any BCa that does occur may have different clinical presentations and underlying mechanisms compared with cisgender women and men. Overall, the limitations for clinical studies and discrepancies among preclinical studies warrant further investigation.

Racial Disparity in Quadruple Negative Breast Cancer: Aggressive Biology and Potential Therapeutic Targeting and Prevention

Simple Summary

Quadruple negative breast cancer (QNBC), a subgroup of triple negative BC, has emerged as a highly aggressive BC subtype that disproportionately afflicts and impacts Black/African-American (AA) women. In this article, we review molecular distinctions in Black/AA and White/European-American (EA) QNBC biology as well as address potential non-genetic risk factors that could be underlying this racially disparate burden. We aim to provide deeper insight and provide a framework for novel discovery of actionable therapeutic targets and identify lifestyle changes to improve outcomes for Black/AA QNBC patients.

Abstract

Black/African-American (AA) women, relative to their White/European-American (EA) counterparts, experience disproportionately high breast cancer mortality. Central to this survival disparity, Black/AA women have an unequal burden of aggressive breast cancer subtypes, such as triple-negative breast cancer (ER/PR-, HER2-wild type; TNBC). While TNBC has been well characterized, recent studies have identified a highly aggressive androgen receptor (AR)-negative subtype of TNBC, quadruple-negative breast cancer (ER/PR-, HER2-wildtype, AR-; QNBC). Similar to TNBC, QNBC disproportionately impacts Black/AA women and likely plays an important role in the breast cancer survival disparities experienced by Black/AA women. Here, we discuss the racial disparities of QNBC and molecular signaling pathways that may contribute to the aggressive biology of QNBC in Black/AA women. Our immediate goal is to spotlight potential prevention and therapeutic targets for Black/AA QNBC; ultimately our goal is to provide greater insight into reducing the breast cancer survival burden experienced by Black/AA women.

Individual Benefits and Risks of Intravaginal Estrogen and Systemic Testosterone in the Management of Women in the Menopause, With a Discussion of Any Associated Risks for Cancer Development

ABSTRACT

Several formulations of intravaginal oestrogen are available for the treatment of genitourinary syndrome of menopause (GSM). These are safe and effective treatments for the symptoms of GSM. Licensed doses of intravaginal oestrogen do not elevate systemic estradiol levels above the normal postmenopausal range with long term use and there is no evidence of an increased risk of coronary heart disease, stroke, thromboembolism, colorectal cancer, endometrial cancer, breast cancer or breast cancer recurrence with their use. This should reassure both women and their healthcare professionals and should lead to more women receiving these localised, vaginally administered hormonal treatments. Available evidence also suggests a positive safety profile for transdermal testosterone treatment when delivered at physiological concentrations.

Transgender patients' perspectives on their cancer genetic counseling experiences

Transgender (trans) individuals face many forms of discrimination in accessing health care, including lack of provider knowledge and denial of services. Barriers specific to the cancer setting include limited availability of information concerning cancer management and its potential impact on gender affirmation therapies and minimal training for providers regarding inclusive practices for the trans population. The limited research about the experiences of cancer genetic counseling for trans patients has investigated exclusively the perspective of the provider, not the patient. This constructivist grounded theory study sought to fill this gap in the literature by interviewing trans individuals who had undergone cancer genetic counseling. Participants were recruited through social media platforms, LGBTQ+ advocacy and cancer support groups, and the National Society of Genetic Counselors' list serv. Six semi-structured interviews were conducted with participants focusing on their expectations and goals prior to the genetic counseling session, concerns during the session, and reflections on inclusive practices. Transcripts were coded and analyzed using a constant comparative approach and five themes emerged: (a) Anxiety for the consult, (b) Disruptions of familial relationships and emotional support systems, (c) Use of inclusive language during session, (d) Impact on gender affirmation journey, and (e) Lack of appropriate cancer risk information for trans patients. The results from this pilot study suggest that trans patients experience anticipatory anxiety before the genetic counseling appointment, particularly about the potential of a physical examination. They may be more likely to experience disrupted family relationships that impact access to family history information and support. Genetic counselors should utilize inclusive language both when referring to the patient and when discussing cancer risk. Finally, additional research is needed to provide more accurate cancer risk predictions for trans individuals.

Arming androgen receptors to oppose oncogenic estrogen receptor activity in breast cancer

Most breast cancers are driven by oncogenic activity of the estrogen receptor alpha (ER). Resistance to ER target therapies is the major cause of breast cancer death. Recently, there has been renewed interest in targeting the androgen receptor (AR) to treat ER-driven breast cancers. Herein, we discuss evidence for an AR agonist, not antagonist, treatment strategy.

Pharmacotherapeutic options for the treatment of menopausal symptoms

Introduction: Menopausal symptoms can be very overwhelming for women. Over the years, many pharmacotherapeutic options have been tested, and others are still being developed. Hormone therapy (HT) is the most efficient therapy for managing vasomotor symptoms and related disturbances. The term HT comprises estrogens and progestogens, androgens, tibolone, the tissue-selective estrogen complex (TSEC), a combination of bazedoxifene and conjugated estrogens, and the selective estrogen receptor modulators, such as ospemifene. Estrogens and progestogens and androgens may differ significantly for chemical structure and can be delivered through different routes, thereby displaying various pharmacological and clinical properties. Tibolone, TSEC and SERM also exhibit unique pharmacodynamics that can be exploited to obtain distinctive therapeutic effects. Non-hormonal options fall mainly into the selective serotonin reuptake inhibitor (SSRI) and selective noradrenergic reuptake inhibitor (SNRI), GABA-analogue drug classes.Areas covered: Herein, the authors describe the pharmacokinetics and pharmacodynamics of hormonal (androgens, estrogens, progestogens, tibolone, TSEC, SERMs) and non-hormonal (SSRIs, SNRIs, Gabapentin, Pregabalin, Oxybutynin, Neurokinin antagonists) treatments for menopausal symptoms and report essential clinical trial data in humans.Expert opinion: Patient tailoring of treatment is key to managing symptoms of menopause. Physicians must have in-depth knowledge of the pharmacology of compounds to tailor therapy to the individual patient's characteristics and needs.

Breast Cancer Incidence Reduction in Women Treated with Subcutaneous Testosterone: Testosterone Therapy and Breast Cancer Incidence Study

Objective

Testosterone (T) therapy has been shown to be breast protective in both pre- and post-menopausal patients. Additionally, estradiol (E) does not cause breast cancer (BC) in the majority of the world's literatures. This study aimed to investigate the incidence of invasive BC (IBC) in pre- and postmenopausal women treated with T therapy and T in combination with E (T/E).

Materials and Methods

Since January 2010, a total of 2,377 pre- and post-menopausal women were treated with T or T/E implants. IBC rates were reported based on newly diagnosed IBC cases in the total study. Total cases divided by the total sample size and years in study was expressed as an incidence per 100,000 person-years (P-Ys). The BC incidence was compared with age-specific Surveillance Epidemiology and End Results (SEER) incidence rates.

Results

As of October 2020, 14 cases diagnosed with IBC have been found in 9,746 P-Y of follow up for an incidence of 144 cases per 100,000 P-Y, substantially less than the age-specific SEER incidence rates (223/100,000), placebo arm of Women's Health Initiative Study (330/100,000), and never users of hormone therapy from the Million Women Study (312/100,000).

Conclusion

T and/or T/E pellet implants significantly reduced the incidence of BC in pre- and post-menopausal women. The addition of E did not increase the incidence over using T alone. This is the second multi-year long-term study demonstrating the benefits of T therapy in reducing the incidence of IBC.

Considerations in genetic counseling of transgender patients: Cultural competencies and altered disease risk profiles

Transgender people are a growing population with specific healthcare needs, barriers to care, and disease risk factors. Cultural competencies for working with transgender people in healthcare settings are essential to reduce barriers to care and combat the associated health disparities. Genetic counselors support their patients to understand and manage medically and personally complex life events and decisions. A genetic counselor caring for a transgender patient or a patient with a transgender relative will therefore require specific cultural competencies and medical knowledge that may not have been covered in their training. Transgender health is also a relatively young field in which new insights may quickly become fundamental. The present paper therefore provides an overview of current best practices for culturally sensitive working with transgender patients, and an introduction to the additional considerations for assessment of disease risk in transgender people. Guidance on how to ensure communication with patients and other stakeholders is inclusive and affirming of transgender identities, is offered. Medical interventions used for gender transitions are described, and their (potential) effects on cancer and cardiovascular disease risk are discussed. Furthermore, the effects of sociocultural risk factors such as minority stress are outlined. In sum, we invite the reader to consider the specific biological, psychological, and social context of the consultation. Finally, we explore culturally competent approaches to pedigree charting and physical examinations with transgender people and provide recommendations for practice.

Morphological and Functional Changes in Skin of Adult Male Rats Chronically Treated with Letrozole, a Nonsteroidal Inhibitor of Cytochrome P450 Aromatase

Skin is a target for hormones and a site of hormone production. Aromatase inhibitors such as letrozole reduce circulating estrogen. The aim of the study was to investigate the morphology of the dermis and immunoexpression of androgen receptor (AR), estrogen receptor α and β (ERα, ERβ), luteinizing hormone receptor (LHR), follicle-stimulating hormone receptor (FSHR), and cytochrome P450 aromatase (P450arom) in male rats with a deficit of estradiol. Experiments were performed on skin of 12 male rats. Rats in the experimental group received per os letrozole for 6 months. For morphological analysis, van Gieson, Sirius Red and orcein staining of sections was performed. In immunohistochemistry, reactions with specific antibodies (anti-P450arom, LHR, FSHR, ERα, ERβ) were used. In morphometric analysis, sections were stained with hematoxylin and eosin. Differences between groups were assessed by Mann-Whitney U-test. There were no differences in the diameter of collagen fibers. The dermis of letrozole-treated animals showed areas without collagen fibers, and expression of P450arom, ERα and ERβ was diminished in the skin of these animals. This study indicates that estrogens exert an effect via ERs that has a role in maintaining proper skin morphology in males, together with androgen. This is also the first documented expression of FSHR in the skin of male rats.

Androgen Receptor in Breast Cancer-Clinical and Preclinical Research Insights

The Androgen Receptor (AR) is emerging as an important factor in the pathogenesis of breast cancer (BC), which is the most common malignancy among females worldwide. The concordance of more than 70% of AR expression in primary and metastatic breast tumors implies that AR may be a new marker and a potential therapeutic target among AR-positive breast cancer patients. Biological insight into AR-positive breast cancer reveals that AR may cross-talk with several vital signaling pathways, including key molecules and receptors. AR exhibits different behavior depending on the breast cancer subtype. Preliminary clinical research using AR-targeted drugs, which have already been FDA-approved for prostate cancer (PC), has given promising results for AR-positive breast cancer patients. However, since the prognostic and predictive value of AR positivity remains uncertain, it is difficult to identify and stratify patients that would benefit from AR-targeted therapies. Herein, through a review of preclinical studies, clinical studies, and clinical trials, we summarize the biology of AR, its prognostic and predictive value, as well as its therapeutic implications by breast cancer molecular subtype.

AIB1 sequestration by androgen receptor inhibits estrogen-dependent cyclin D1 expression in breast cancer cells

Background

Androgens, through their own receptor, play a protective role on breast tumor development and progression and counterbalance estrogen-dependent growth stimuli which are intimately linked to breast carcinogenesis.

Methods

Cell counting by trypan blu exclusion was used to study androgen effect on estrogen-dependent breast tumor growth. Quantitative Real Time RT–PCR, western blotting, transient transfection, protein immunoprecipitation and chromatin immunoprecipitation assays were carried out to investigate how androgen treatment and/or androgen receptor overexpression influences the functional interaction between the steroid receptor coactivator AIB1 and the estrogen- or androgen receptor which, in turn affects the estrogen-induced cyclin D1 gene expression in MCF-7 breast cancer cells. Data were analyzed by ANOVA.

Results

Here we demonstrated, in estrogen receptor α (ERα)-positive breast cancer cells, an androgen-dependent mechanism through which ligand-activated androgen receptor (AR) decreases estradiol-induced cyclin D1 protein, mRNA and gene promoter activity. These effects involve the competition between AR and ERα for the interaction with the steroid receptor coactivator AIB1, a limiting factor in the functional coupling of the ERα with the cyclin D1 promoter. Indeed, AIB1 overexpression is able to reverse the down-regulatory effects exerted by AR on ERα-mediated induction of cyclin D1 promoter activity. Co-immunoprecipitation studies indicated that the preferential interaction of AIB1 with ERα or AR depends on the intracellular expression levels of the two steroid receptors. In addition, ChIP analysis evidenced that androgen administration decreased E₂-induced recruitment of AIB1 on the AP-1 site containing region of the cyclin D1 gene promoter.

Conclusions

Taken together all these data support the hypothesis that AIB1 sequestration by AR may be an effective mechanism to explain the reduction of estrogen-induced cyclin D1 gene activity. In estrogen-dependent breast cancer cell proliferation, these findings reinforce the possibility that targeting AR signalling may potentiate the effectiveness of anti-estrogen adjuvant therapies.

The drugs that mostly frequently induce gynecomastia: A national case - noncase study

AIMS

Drug-induced gynecomastia accounts for up to 25% of cases of gynecomastia. The objective of the present study was to provide a comprehensive overview of drug-induced gynecomastia on the basis of spontaneously reported adverse drug reactions (ADRs) in the French national pharmacovigilance database (FPVD).

METHODS

We performed a case - noncase study of drug-induced gynecomastia. Cases corresponded to reports of gynecomastia recorded in the FPVD between 1 January 2008 and 31 December 2015. The noncases corresponded to all other spontaneously reported ADRs recorded in the FPVD during the same period. Data were expressed as the reporting odds ratio (ROR) and its 95% confidence interval.

RESULTS

Of the 255,354 ADRs recorded in the FPVD between 1 January 2008 and 31 December 2015, 327 (0.31%) of relevant cases of gynecomastia and 106,800 noncases were analyzed. The RORs were statistically significant for 54 active compounds mentioned 429 times in cases of gynecomastia. A single drug was involved in 59% of cases. The most frequently implicated drug classes were antiretrovirals (23.5%), diuretics (15.5%), proton pump inhibitors (11.9%), HMG-CoA reductase inhibitors (9.1%), neuroleptics and related drugs (6.5%), calcium channel blockers (6.3%), and 5-alpha reductase inhibitors (4%).

CONCLUSIONS

A comprehensive analysis of a national pharmacovigilance database highlighted the main drug classes suspected of inducing gynecomastia. A physiopathological mechanism (a hormone imbalance with elevated estrogen levels) is known or suspected for most of the drugs involved in gynecomastia. However, we noticed a lack of harmonization in the summary of product characteristics for original vs. generic medicines.

Pre-diagnostic sex hormone levels and survival among breast cancer patients

PURPOSE

Higher levels of circulating sex steroid hormones are associated with increased breast cancer risk, though their association with prognosis remains unclear. We evaluated the association between circulating sex hormone levels and breast cancer survival in two large cohorts.

METHODS

We evaluated this association among 2073 breast cancer cases from the Nurses' Health Study (NHS) and Nurses' Health Study II (NHSII) cohorts. Women in this analysis provided a blood sample in 1989-1990 (NHS) or in 1996-1999 (NHSII) and were subsequently diagnosed with breast cancer. Levels of estradiol (postmenopausal women only), testosterone, dehydroepiandrosterone-sulfate (DHEAS), and sex hormone-binding globulin (SHBG) were measured in plasma. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for survival, adjusting for patient and tumor characteristics.

RESULTS

A total of 639 deaths and 160 breast cancer deaths occurred over follow-up through 2015. Compared to women in the lowest quartile, postmenopausal women in the highest quartile of estradiol experienced a 1.43-fold overall mortality rate (HR 1.43, 95% CI 1.03-1.97, P-trend = 0.04) and a nonsignificantly higher breast cancer mortality rate (HR 1.50, 95% CI 0.75-2.98, P-trend = 0.12). Higher DHEAS levels were nonsignificantly associated with better overall survival (HR_Q4vsQ1=0.79, 95% CI 0.57-1.10, P-trend = 0.05), though not with breast cancer survival. No associations were observed between testosterone or SHBG and survival.

CONCLUSIONS

Pre-diagnostic postmenopausal circulating estradiol levels were modestly associated with worse survival among breast cancer patients. Further studies should evaluate whether circulating hormone levels at diagnosis predict cancer prognosis or treatment response.

Androgen receptor expression in normal breast tissue and subsequent breast cancer risk

Sex steroid hormone signaling is critical in the development of breast cancers, although the role of the androgen receptor remains unclear. This study evaluated androgen receptor (AR) expression in normal breast tissue as a potential marker of breast cancer risk. We conducted a nested case-control study of women with benign breast disease (BBD) within the Nurses' Health Studies. Epithelial AR expression was assessed by immunohistochemistry in normal tissue from the BBD biopsy and the percent of positive nuclei was estimated in ordinal categories of 10% for 78 breast cancer cases and 276 controls. Logistic regression models adjusting for the matching factors and BBD lesion type were used to calculate odds ratios (ORs) for the association between AR expression (tertiles: ≤10%, 11-30%, and >30%) and breast cancer risk. AR expression in normal breast tissue was not associated with subsequent breast cancer risk (OR_T3vsT1 = 0.9, 95% CI = 0.4-1.8, p trend = 0.68). In comparison with low AR/low ER women, ORs of 0.4 (95% CI = 0.1-1.2) for high AR/high ER women, 1.8 (95% CI = 0.4-7.8) for low AR/high ER women, and 0.7 (95% CI = 0.3-1.6) for high AR/low ER women were observed (p interaction = 0.21). Ki67 did not modify the association between AR expression and breast cancer risk (p interaction = 0.75). There was little evidence for an overall association between AR expression in normal breast tissue and breast cancer risk. These findings did not show that the AR association varied by Ki67 expression in normal breast tissue, though there was suggestive heterogeneity by ER expression.

Strong androgen receptor expression can aid in distinguishing GATA3+ metastases

GATA3 is a transcription factor used clinically as a marker of breast or urothelial differentiation. A marker is yet needed to distinguish this in the case of the GATA3-positive tumor of unknown origin. We tested classical markers of breast differentiation and hormonal signaling to see which correlated strongest with GATA3 expression in breast cancer and thus which could help correctly identify breast origin in the case of the GATA3-positive tumor of unknown origin. GATA3, estrogen receptor, progesterone receptor, androgen receptor (AR), HER2, GCDFP15, and mammaglobin expression was intercorrelated in a histologically diverse 259-case breast cancer tissue microarray. We show herein a uniquely high level of correlation between GATA3 and AR expression (r=0.61; 95% confidence interval 0.52-0.68) that was strongest among lobular carcinomas (r=1; 95% confidence interval 0.73-1) and stronger than any other correlation studied. Separate AR staining of 10 metastatic GATA3+ carcinomas of urothelial origin and 13 metastatic GATA3+ carcinomas of breast origin showed that strong AR staining (>60% of tumor cells) has a sensitivity of 54% and a specificity of 100% for correctly distinguishing GATA3+ carcinoma of mammary origin from urothelial origin in the metastatic setting. Androgen receptor expression is strongly correlated with GATA3 in breast cancer, particularly in tumors with lobular morphology. Strong AR expression (>60% of tumor cells) is an excellent test to rule out urothelial carcinoma in the GATA3+ metastatic setting (specificity 100%) and will effectively identify breast origin in approximately 50% of cases.

5α-dihydrotestosterone reduces renal Cyp24a1 expression via suppression of progesterone receptor

Androgens act in concert with vitamin D to influence reabsorption of calcium. However, it is unclear whether androgens directly regulate vitamin D homeostasis or control other cellular events that are related to vitamin D metabolism. To examine whether the expression of vitamin D-related genes in mouse kidney is driven by androgens or androgen-dependent effects, the androgen receptor and other sex steroid receptors were monitored in orchidectomized mice treated with 5α-dihydrotestosterone (DHT). Our results revealed that exposing orchidectomized mice to DHT inhibited the expression of progesterone receptor (Pgr) with or without estrogen receptor α expression, the latter was confirmed by ER-positive (MCF7 and T47D) or -negative (PCT) cells analysis. The loss of Pgr in turn decreased the expression of renal 24-hydroxylase via transcriptional regulation because Cyp24a1 gene has a progesterone receptor-binding site on promoter. When male kidneys preferentially hydroxylate 25-hydroxyvitamin D₃ using 24-hydroxylase rather than 25-hydroxyvitamin D₃-1-alpha hydroxylase, DHT suppressed the Pgr-mediated 24-hydroxylase expression, and it is important to note that DHT increased the blood 25-hydroxyvitamin D₃ levels. These findings uncover an important link between androgens and vitamin D homeostasis and suggest that therapeutic modulation of Pgr may be used to treat vitamin D deficiency and related disorders.

A Presurgical Study of Lecithin Formulation of Green Tea Extract in Women with Early Breast Cancer

Epidemiologic data support an inverse association between green tea intake and breast cancer risk. Greenselect Phytosome (GSP) is a lecithin formulation of a caffeine-free green tea catechin extract. The purpose of the study was to determine the tissue distribution of epigallocatechin-3-O-gallate (EGCG) and its effect on cell proliferation and circulating biomarkers in breast cancer patients. Twelve early breast cancer patients received GSP 300 mg, equivalent to 44.9 mg of EGCG, daily for 4 weeks prior to surgery. The EGCG levels were measured before (free) and after (total) enzymatic hydrolysis by HPLC-MS/MS in plasma, urine, breast cancer tissue, and surrounding normal breast tissue. Fasting blood samples were taken at baseline, before the last administration, and 2 hours later. Repeated administration of GSP achieved levels of total EGCG ranging from 17 to 121 ng/mL in plasma. Despite a high between-subject variability, total EGCG was detectable in all tumor tissue samples collected up to 8 ng/g. Median total EGCG concentration was higher in the tumor as compared with the adjacent normal tissue (3.18 ng/g vs. 0 ng/g, P = 0.02). Free EGCG concentrations ranged from 8 to 65.8 ng/mL in plasma (P between last administration and 2 hours after <0.001). Free EGCG plasma levels showed a significant positive correlation with the Ki-67 decrease in tumor tissue (P = 0.02). No change in any other biomarkers was noted, except for a slight increase in testosterone levels after treatment. Oral GSP increases bioavailability of EGCG, which is detectable in breast tumor tissue and is associated with antiproliferative effects on breast cancer tissue. Cancer Prev Res; 10(6); 363-9. ©2017 AACR.

Cancer in Transgender People: Evidence and Methodological Considerations

Transgender people comprise a diverse group of individuals whose gender identity or expression differs from that originally assigned to them at birth. Some, but not all, transgender people elect to undergo medical gender affirmation, which may include therapy with cross-sex hormones and/or surgical change of the genitalia and other sex characteristics. As cross-sex hormones administered for the purposes of gender affirmation may be delivered at high doses and over a period of decades, the carcinogenicity of hormonal therapy in transgender people is an area of considerable concern. In addition, concerns about cancer risk in transgender patients have been linked to sexually transmitted infections, increased exposure to well-known risk factors such as smoking and alcohol use, and the lack of adequate access to screening. Several publications have identified cancer as an important priority in transgender health research and called for large-scale studies. The goals of this article are to summarize the evidence on factors that may differentially affect cancer risk in transgender people, assess the relevant cancer surveillance and epidemiologic data available to date, and offer an overview of possible methodological considerations for future studies investigating cancer incidence and mortality in this population.

Androgen action in female reproductive physiology

PURPOSE OF REVIEW

In the last decade, it has been proven that androgens acting via the androgen receptor (AR) play an important role in the regulation of female reproductive function. However, the specific site of action and the precise pathways involved remain to be fully elucidated. This review aims to combine findings from emerging basic research to provide new insights into the roles of AR-mediated actions, and the mechanisms involved, in normal ovarian, uterine, and mammary gland function.

RECENT FINDINGS

Our understanding of the specific roles of androgens in females has been hindered as females with complete androgen insensitivity cannot be generated by natural breeding, and interpretation of results from pharmacological studies has led to confusion as some androgens can be converted into estrogens, which can mediate actions via estrogen receptors. However, with the creation of global and cell-specific female AR knockout mouse models by Cre-LoxP technology, and the use of aromatizable and nonaromatizable androgens, novel roles for androgens in the regulation of female reproductive physiology have been revealed.

SUMMARY

AR-mediated mechanisms play important roles in mediating normal ovarian, uterine, and mammary gland function and there is hope that further elucidation of the role of androgens in female reproductive physiology may translate into the development of novel, evidence-based, and targeted treatment for androgen-associated conditions.

Sex Hormones and Tendon

The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood. The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet, in active young female athletes, physiological high concentration of estrogen may enhance the risk of injuries due to reduced fibrillar crosslinking and enhanced joint laxity. In men, testosterone can enhance tendon stiffness due to an enhanced tendon collagen turnover and collagen content, but testosterone has also been linked to a reduced responsiveness to relaxin. The present chapter will focus on sex difference in tendon injury risk, tendon morphology and tendon collagen turnover, but also on the specific effects of estrogen and androgens.

Western-style diet, with and without chronic androgen treatment, alters the number, structure, and function of small antral follicles in ovaries of young adult monkeys

OBJECTIVE

To examine the small antral follicle (SAF) cohort in ovaries of adult rhesus monkeys after consumption of a Western-style diet (WSD), with or without chronically elevated androgen levels since before puberty.

DESIGN

Cholesterol or T (n = 6 per group) implants were placed SC in female rhesus macaques beginning at 1 year of age (prepubertal), with addition of a WSD (high fat/fructose) at 5.5 years (menarche approximately 2.6 years). Ovaries were collected at 7 years of age. One ovary per female was embedded in paraffin for morphologic and immunohistochemical analyses. The SAFs (<2.5 mm) were dissected from the other ovary obtained at or near menses in a subgroup of females (n = 3 per group) and processed for microarray analyses of the SAF transcriptome. Ovaries of adult monkeys consuming a standard macaque diet (low in fats and sugars) were obtained at similar stages of the menstrual cycle and used as controls for all analyses.

SETTING

Primate research center.

ANIMAL(S)

Adult, female rhesus monkeys (Macaca mulatta).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURES

Histologic analyses, SAF counts and morphology, protein localization and abundance in SAFs, transcriptome in SAFs (messenger RNAs [mRNAs]).

RESULT(S)

Compared with controls, consumption of a WSD, with and without T treatment, increased the numbers of SAFs per ovary, owing to the presence of more atretic follicles. Numbers of granulosa cells expressing cellular proliferation markers (pRb and pH3) was greater in healthy SAFs, whereas numbers of cells expressing the cell cycle inhibitor (p21) was higher in atretic SAFs. Intense CYP17A1 staining was observed in the theca cells of SAFs from WSD with or without T groups, compared with controls. Microarray analyses of the transcriptome in SAFs isolated from WSD and WSD plus T-treated females and controls consuming a standard diet identified 1,944 genes whose mRNA levels changed twofold or more among the three groups. Further analyses identified several gene pathways altered by WSD and/or WSD plus T associated with steroid, carbohydrate, and lipid metabolism, plus ovarian processes. Alterations in levels of several SAF mRNAs are similar to those observed in follicular cells from women with polycystic ovary syndrome.

CONCLUSION(S)

These data indicate that consumption of a WSD high in fats and sugars in the presence and absence of chronically elevated T alters the structure and function of SAFs within primate ovaries.

Androgen receptor inactivation resulted in acceleration in pubertal mammary gland growth, upregulation of ERα expression, and Wnt/β-catenin signaling in female mice

The androgen receptor (AR) is widely expressed in mammary cells of female mammals including humans and mice, indicating a possible role for AR-mediated androgen actions in breast development, function, and pathology, although the specific mechanisms remain unclear. To elucidate the mechanisms of androgen action in mammary gland physiology and development, we used AR-knockout (AR(Δex3)KO) female mice with a universally expressed, transcriptionally inactive AR protein harboring an in-frame deletion of its second zinc finger. Although in sexually mature wild-type (WT) and AR(ex3Δ)KO females, the mammary epithelial growth was fully extended to the edge of the fat pad, during puberty, AR(ex3Δ)KO females exhibit significantly accelerated mammary ductal growth and an increased number of terminal end buds compared with WT females. Accelerated AR(ex3Δ)KO female mammary growth was associated with significantly increased mammary epithelial ERα expression and activated Wnt/β-catenin signaling as shown by increased Wnt4 expression and accumulation of nuclear β-catenin. These findings are consistent with increased mammary estrogen exposure although ovarian estradiol content was unchanged compared with WT females. Furthermore, treatment with the potent pure androgen DHT markedly reduced ductal extension and terminal end bud numbers in WT but not in AR(Δex3)KO females, further supporting the concept that AR-mediated, androgen-induced suppression of murine mammary growth is a physiological characteristic of puberty. In summary, our findings reveal an inhibitory role of AR-mediated androgen actions in pubertal mammary gland development by reducing epithelial cell proliferation and could be mediated by regulation of Wnt/β-catenin signaling.

The impact of testosterone, tibolone and black cohosh on purified mammary and placental 17β-hydroxysteroid dehydrogenase type 1

CONTEXT

Mammary and placental 17β-hydroxysteroid dehydrogenase type 1 (17βHSD1).

OBJECTIVE

To assess the impact of testosterone, tibolone, and black cohosh on purified mammary and placental 17βHSD1.

MATERIALS AND METHODS

17βHSD1 was purified from human mammary gland and placenta by column chromatography, its activity was monitored by a radioactive activity assay, and the degree of purification was determined by gel electrophoresis. Photometric cofactor transformation analysis was performed to assess 17βHSD1 activity without or in presence of testosterone, tibolone and black cohosh.

RESULTS

17βHSD1 from both sources displayed a comparable basal activity. Testosterone and tibolone metabolites inhibited purified mammary and placental 17βHSD1 activity to a different extent, whereas black cohosh had no impact.

DISCUSSION

Studies on purified enzymes reveal the individual action of drugs on local regulatory mechanisms thus helping to develop more targeted therapeutic intervention.

CONCLUSION

Testosterone, tibolone and black cohosh display a beneficial effect on local mammary estrogen metabolism by not affecting or decreasing local estradiol exposure.

Complexities of androgen receptor signalling in breast cancer

While the clinical benefit of androgen-based therapeutics in breast cancer has been known since the 1940s, we have only recently begun to fully understand the mechanisms of androgen action in breast cancer. Androgen signalling pathways can have either beneficial or deleterious effects in breast cancer depending on the breast cancer subtype and intracellular context. This review discusses our current knowledge of androgen signalling in breast cancer, including the relationship between serum androgens and breast cancer risk, the prognostic significance of androgen receptor (AR) expression in different breast cancer subtypes and the downstream molecular pathways mediating androgen action in breast cancer cells. Intracrine androgen metabolism has also been discussed and proposed as a potential mechanism that may explain some of the reported differences regarding dichotomous androgen actions in breast cancers. A better understanding of AR signalling in this disease is critical given the current resurgence in interest in utilising contemporary AR-directed therapies for breast cancer and the need for biomarkers that will accurately predict clinical response.

Revising the role of the androgen receptor in breast cancer

Breast cancer (BC) is traditionally viewed as an oestrogen-dependent disease in which the androgen receptor (AR) is inhibitory, counteracting the oncogenic activity of oestrogen receptor α (ERα (ESR1)). Most probably as a result of this crosstalk, the AR has prognostic value in ER-positive disease, with AR positivity reported to correlate with a better prognosis. Activation of the AR pathway has been previously used as a therapeutic strategy to treat BC, but its usage declined following the introduction of the anti-oestrogen tamoxifen. More recently, it has been demonstrated that a subset of triple-negative BCs (molecular apocrine) are dependent upon androgen signalling for growth and therapies that inhibit androgen signalling, currently used for the treatment of prostate cancer, e.g. the antiandrogen bicalutamide and the CYP17 inhibitor abiraterone acetate are undergoing clinical trials to investigate their efficacy in this BC subtype. This review summarises the current knowledge of AR activity in BC.

Hormonal control of stem cell systems

Many organs respond to physiological challenges by changing tissue size or composition. Such changes may originate from tissue-specific stem cells and their supportive environment (niche). The endocrine system is a major effector and conveyor of physiological changes and as such could alter stem cell behavior in various ways. In this review, we examine how hormones affect stem cell biology in four different organs: the ovary, intestine, hematopoietic system, and mammary gland. Hormones control every stage of stem cell life, including establishment, expansion, maintenance, and differentiation. The effects can be cell autonomous or non-cell autonomous through the niche. Moreover, a single hormone can affect different stem cells in different ways or affect the same stem cell differently at various developmental times. The vast complexity and diversity of stem cell responses to hormonal cues allow hormones to coordinate the body's reaction to physiological challenges.

The Role of the Androgen Receptor in Triple-Negative Breast Cancer

Greater than 70% of human breast cancers express the androgen receptor (AR). Emerging preclinical and clinical data suggest that AR may play a role in breast cancer pathogenesis and may serve as a therapeutic target in certain more difficult-to-treat breast cancer subtypes, such as triple-negative breast cancer. Although this is an area of active investigation, the clinical significance of this hormone receptor as a prognostic/predictive marker and its functional role in tumorigenesis is unclear. This review provides an update on the advances made in the last several years regarding the role of AR as a prognostic/predictive biomarker in breast cancer, the underlying biology of AR signaling in breast cancer development and the available clinical data for the use of androgen inhibition in the treatment of AR+ triple-negative breast cancer.

Androgen receptors and serum testosterone levels identify different subsets of postmenopausal breast cancers

BACKGROUND

Androgen receptors (AR) are frequently expressed in breast cancers, but their implication in cancer growth is still controversial. In the present study, we further investigated the role of the androgen/AR pathway in breast cancer development.

METHODS

AR expression was evaluated by immunochemistry in a cohort of 528 postmenopausal breast cancer patients previously examined for the association of serum testosterone levels with patient and tumor characteristics. AR expression was classified according to the percentage of stained cells: AR-absent (0%) and AR-poorly (1%-30%), AR-moderately (>30%-60%), and AR-highly (>60%) positive.

RESULTS

Statistical analysis was performed in 451 patients who experienced natural menopause. AR-high expression was significantly related with low histologic grade and estrogen receptor (ER)- and progesterone receptor (PR)-positive status (P trend<0.001). Mean testosterone levels were significantly higher in the AR-high category than in the other categories combined (P=0.022), although a trend across the AR expression categories was not present. When women defined by ER status were analyzed separately, regression analysis in the ER-positive group showed a significant association of high testosterone levels with AR-highly-positive expression (OR 1.86; 95% CI, 1.10-3.16), but the association was essentially due to patients greater than or equal to 65 years (OR 2.42; 95% CI, 1.22-4.82). In ER-positive group, elevated testosterone levels appeared also associated with AR-absent expression, although the small number of patients in this category limited the appearance of significant effects (OR 1.92; 95% CI, 0.73-5.02): the association was present in both age groups (<65 and ≥65 years). In the ER-negative group, elevated testosterone levels were found associated (borderline significance) with AR-absent expression (OR 2.82, 95% CI, 0.98-8.06). In this ER-negative/AR-absent subset of tumors, elevated testosterone levels cannot stimulate cancer growth either directly or after conversion into estrogens, but they probably induce increased synthesis of some other substance that is responsible for cancer growth through binding to its specific receptor.

CONCLUSIONS

The findings in the present study confirm that testosterone levels are a marker of hormone-dependent breast cancer and suggest that the contemporary evaluation of ER status, AR expression, and circulating testosterone levels may identify different subsets of cancers whose growth may be influenced by androgens.

Androgen resistance in female mice increases susceptibility to DMBA-induced mammary tumors

Hormones, notably estrogens, are pivotal in the origins of breast cancer but androgenic effects, while supported by persistence of AR expression in breast cancers, remain controversial. This study determined the role of the androgen actions via androgen receptor (AR) in experimental mammary cancer. Androgen-resistant female and male mice (ARKO) were generated using Cre/loxP technique and featured a global AR inactivation. The effect of AR inactivation and influence of genetic background on 7,12-dimethylbenz[a]anthracene (DMBA)-induced tumorigenesis was confirmed using two separate ARKO models with different genetic backgrounds. The onset of palpable mammary tumors was significantly faster in ARKO females (median time 22 vs 34 weeks, respectively; (p = 0.0024; multivariate Cox regression) compared to WT and independent of the mouse genetic background. The cumulative incidence at 9 months was 81 ± 10% [mean ± SE] for ARKO compared to 50 ± 13% in WT females. The increased DMBA susceptibility of ARKO females was associated with a higher epithelial proliferation index but not with major structural or receptor (estrogen or progesterone) expression differences between the virgin WT or ARKO female mammary glands. AR inactivation allowed substantial ductal extension in ARKO males while WT males displayed only rudimentary epithelial branches or complete regression of epithelial structures. Yet, DMBA did not induce epithelial mammary tumors in WT or ARKO males, demonstrating that AR inactivation alone is insufficient to promote mammary tumors. These results demonstrate that AR inactivation accelerates mammary carcinogenesis in female mice exposed to the chemical carcinogen DMBA regardless of mouse genetic background but require prior exposure to endogenous ovarian hormones.

The safety of postmenopausal testosterone therapy

Testosterone is increasingly used as part of postmenopausal HRT regimens. Unfortunately, few androgenic preparations designed specifically for use in women have been approved by regulatory authorities. Ongoing concerns exist surrounding the potential long-term effects of testosterone therapy. Here, we review the most recent data on postmenopausal testosterone therapy, focusing particularly on the effects of testosterone on breast, endometrium and cardiovascular health.

Accelerated mammary tumor onset in a HER2/Neu mouse model exposed to DDT metabolites locally delivered to the mammary gland

BACKGROUND

The association of DDT (dichlorodiphenyltrichloroethane) with breast cancer is controversial, but animal studies directly linking DDT to risk are lacking. Concerns with DDT reside in its environmental persistence, bioaccumulation in breast adipose tissue, and endocrine-disrupting actions. Whereas most attention has been focused on estrogenic congeners, we tested the cancer-inducing potential of the antiandrogen, p,p´-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene], the most prevalent and persistent DDT metabolite.

OBJECTIVES

We aimed to determine whether developmental exposure to p,p´-DDE stored in adipose tissue surrounding the cancer-prone mammary epithelium of MMTV-Neu mice influences tumor development.

METHODS

For localized delivery, Elvax 40P pellets containing p,p´-DDE were implanted into the mammary fat pads of prepubertal female mice. We compared mammary tumor development with p,p´-DDE with development in response to its estrogenic isomer, o,p´-DDE [1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl) ethylene], and a mixture of both isomers.

RESULTS

p,p´-DDE implants significantly accelerated mammary tumor onset compared with vehicle Elvax implants. o,p´-DDE had similar results, but only at ≤ 10 months of age. Lipid-adjusted levels of p,p´-DDE in mammary adipose tissue and serum in young mice were within the ranges of human exposure, whereas concentrations in aged mice were low to undetectable. Exposure to a 2:1 ratio of p,p´-DDE:o,p´-DDE did not result in the younger latency observed with the individual isomers.

CONCLUSIONS

p,p´-DDE exposure at concentrations relevant to human exposure accelerates mammary carcinogenesis in mice, possibly through hormonal and/or other actions. These data suggest that DDE exposure would promote, but not cause, mammary tumorigenesis. Developmental exposure in immature mammary tissue continues to affect tumor onset even after p,p´-DDE levels have declined. Future studies are needed to determine whether early exposure to p,p´-DDE correspondingly predisposes women to early-onset breast cancer.

Androgens inhibit the stimulatory action of 17β-estradiol on normal human breast tissue in explant cultures

BACKGROUND

The data concerning the effects and safety of androgen in human breast tissue are conflicting.

OBJECTIVE

Our aim was to analyze the effects of androgens on normal human breast tissue (HBT).

APPROACH

We cultured explants of HBT (obtained from reduction mammoplasty operations of postmenopausal women) with or without testosterone (T) and 5α-dihydrotestosterone (DHT) or in combination with 17β-estradiol (E(2)) for 7 and 14 d to study the effects of androgens on proliferation, apoptosis, target gene expression, and steroid receptors. The androgen receptor (AR) and estrogen receptor (ER) dependences of the effects were studied with the antihormones bicalutamide and fulvestrant, respectively.

RESULTS

The hormone responsiveness of cultured breast tissue was assessed by assaying apolipoprotein-D and prostate-specific antigen expression increased by androgens and amphiregulin and trefoil factor-1 expression induced by E(2) treatment. T and DHT reduced proliferation and increased apoptosis in breast epithelium, the effects of which were reversed by bicalutamide. In combination with E(2), they suppressed E(2)-stimulated proliferation and cell survival. DHT also inhibited basal (P < 0.05) and E(2)-induced expression of cyclin-D1 mRNA (P < 0.05). Immunohistochemistry showed that T (P < 0.05) and DHT (P < 0.05) increased the relative number of AR-positive cells, whereas ERα-positive (P < 0.001) cell numbers were strongly decreased. The percentage of ERβ-positive cells remained unchanged. E(2) treatment increased ERα-positive (P < 0.01) cells, whereas AR- (P < 0.05) and ERβ-expressing (P < 0.001) cells diminished. These effects were repressed in combination cultures of E(2) with T and DHT.

CONCLUSION

T and DHT inhibited proliferation and increased apoptosis in the epithelium of cultured normal HBT and opposed E(2)-stimulated proliferation and cell survival in an AR-dependent manner. These effects were associated with changes in the proportions of ERα- and AR-positive epithelial cells.