Spatially distinct epithelial and mesenchymal cell subsets along progressive lineage restriction in the branching embryonic mammary gland.

How cells coordinate morphogenetic cues and fate specification during development remains a fundamental question in organogenesis. The mammary gland arises from multipotent stem cells (MaSCs), which are progressively replaced by unipotent progenitors by birth. However, the lack of specific markers for early fate specification has prevented the delineation of the features and spatial localization of MaSC-derived lineage-committed progenitors. Here, using single-cell RNA sequencing from E13.5 to birth, we produced an atlas of matched mouse mammary epithelium and mesenchyme and reconstructed the differentiation trajectories of MaSCs toward basal and luminal fate. We show that murine MaSCs exhibit lineage commitment just prior to the first sprouting events of mammary branching morphogenesis at E15.5. We identify early molecular markers for committed and multipotent MaSCs and define their spatial distribution within the developing tissue. Furthermore, we show that the mammary embryonic mesenchyme is composed of two spatially restricted cell populations, and that dermal mesenchyme-produced FGF10 is essential for embryonic mammary branching morphogenesis. Altogether, our data elucidate the spatiotemporal signals underlying lineage specification of multipotent MaSCs, and uncover the signals from mesenchymal cells that guide mammary branching morphogenesis.

Upregulation of an estrogen receptor-regulated gene by first generation progestins requires both the progesterone receptor and estrogen receptor alpha.

Progestins, synthetic compounds designed to mimic the activity of natural progesterone (P4), are used globally in menopausal hormone therapy. Although the older progestins medroxyprogesterone acetate (MPA) and norethisterone (NET) have been implicated in increased breast cancer risk, little is known regarding newer progestins, and no significant risk has been associated with P4. Considering that breast cancer is the leading cause of mortality in women, establishing which progestins increase breast cancer incidence and elucidating the underlying mechanisms is a global priority. We showed for the first time that the newer-generation progestin drospirenone (DRSP) is the least potent progestin in terms of proliferation of the estrogen-responsive MCF-7 BUS breast cancer cell line, while NET and P4 have similar potencies to estradiol (E2), the known driver of breast cancer cell proliferation. Notably, MPA, the progestin most frequently associated with increased breast cancer risk, was significantly more potent than E2. While all the progestogens enhanced the anchorage-independent growth of the MCF-7 BUS cell line, MPA promoted a greater number of colonies than P4, NET or DRSP. None of the progestogens inhibited E2-induced proliferation and anchorage-independent growth. We also showed that under non-estrogenic conditions, MPA and NET, unlike P4 and DRSP, increased the expression of the estrogen receptor (ER) target gene, cathepsin D, via a mechanism requiring the co-recruitment of ERα and the progesterone receptor (PR) to the promoter region. In contrast, all progestogens promoted the association of the PR and ERα on the promoter of the PR target gene, MYC, thereby increasing its expression under non-estrogenic and estrogenic conditions. These results suggest that progestins differentially regulate the way the PR and ER converge to modulate the expression of PR and ER-regulated genes. Our novel findings indicating similarities and differences between P4 and the progestins, emphasize the importance of comparatively investigating effects of individual progestins rather than grouping them as a class. Further studies are required to underpin the clinical relevance of PR/ERα crosstalk in response to different progestins in both normal and malignant breast tissue, to either confirm or refute their suitability in combination therapy for ER-positive breast cancer.

Paracrine signalling between intestinal epithelial and tumour cells induces a regenerative programme.

Tumours are complex ecosystems composed of different types of cells that communicate and influence each other. While the critical role of stromal cells in affecting tumour growth is well established, the impact of mutant cancer cells on healthy surrounding tissues remains poorly defined. Here, using mouse intestinal organoids, we uncover a paracrine mechanism by which intestinal cancer cells reactivate foetal and regenerative YAP-associated transcriptional programmes in neighbouring wildtype epithelial cells, rendering them adapted to thrive in the tumour context. We identify the glycoprotein thrombospondin-1 (THBS1) as the essential factor that mediates non-cell-autonomous morphological and transcriptional responses. Importantly, Thbs1 is associated with bad prognosis in several human cancers. This study reveals the THBS1-YAP axis as the mechanistic link mediating paracrine interactions between epithelial cells in intestinal tumours.

In vivo imaging of mammary epithelial cell dynamics in response to lineage-biased Wnt/ß-catenin activation.

Real-time in vivo imaging provides an essential window into the spatiotemporal cellular events contributing to tissue development and pathology. By coupling longitudinal intravital imaging with genetic lineage tracing, here we capture the earliest cellular events arising in response to active Wnt/ß-catenin signaling and the ensuing impact on the organization and differentiation of the mammary epithelium. This enables us to interrogate how Wnt/ß-catenin regulates the dynamics of distinct subpopulations of mammary epithelial cells in vivo and in real time. We show that ß-catenin stabilization, when targeted to either the mammary luminal or basal epithelial lineage, leads to cellular rearrangements that precipitate the formation of hyperplastic lesions that undergo squamous transdifferentiation. These results enhance our understanding of the earliest stages of hyperplastic lesion formation in vivo and reveal that, in mammary neoplastic development, ß-catenin activation dictates a hair follicle/epidermal differentiation program independently of the targeted cell of origin.

Pediatric weight management interventions improve prevalence of overeating behaviors.

OBJECTIVE: To examine changes in prevalence of overeating behaviors in a comparative effectiveness study of two pediatric weight management interventions. METHODS: Four-hundred and seven children, ages 6-12 years, with a BMI ≥ 85th percentile were enrolled in a comparative effectiveness trial of two pediatric weight management interventions. Prevalence of "sneaking, hiding or hoarding food", and 'eating in the absence of hunger' was evaluated at baseline and 12 months. Statistical methods included McNemar's test and longitudinal logistic regression. RESULTS: Prevalence of "sneak, hide, or hoard food" significantly decreased in all participants from 29.1% to 20.7% at 12 months. The prevalence of "eating in the absence of hunger" decreased in all participants from 46.7% to 22.4% at 12 months. Use of SNAP benefits, free/reduced meals at school, parental stress, housing, and food insecurity at baseline were associated with an increased likelihood of endorsing overeating behaviors at 12 months. Conversely, those who engaged in at least one session of the pediatric weight management intervention were significantly less likely to endorse "eating in the absence of hunger" at 12 months. CONCLUSIONS: Participation in pediatric weight management interventions improves the prevalence of overeating behaviors and is associated with participant engagement and social determinants of health, specifically food security status. Efforts to engage populations impacted by food insecurity and other social determinants of health risk factors will be critical for success of weight management interventions. CLINICAL TRIAL REGISTRATION: This trial has been registered at ClinicalTrials.gov (identifier: NCT03012126).

Hormone Therapy and Breast Cancer: Emerging Steroid Receptor Mechanisms.

Although hormone therapy is widely used by millions of women to relieve symptoms of menopause, it has been associated with several side-effects such as coronary heart disease, stroke and increased invasive breast cancer risk. These side-effects have caused many women to seek alternatives to conventional hormone therapy, including the controversial custom-compounded bioidentical hormone therapy suggested to not increase breast cancer risk. Historically estrogens and the estrogen receptor were considered the principal factors promoting breast cancer development and progression, however, a role for other members of the steroid receptor family in breast cancer pathogenesis is now evident, with emerging studies revealing an interplay between some steroid receptors. In this review, we discuss examples of hormone therapy used for the relief of menopausal symptoms, highlighting the distinction between conventional hormone therapy and custom-compounded bioidentical hormone therapy. Moreover, we highlight the fact that not all hormones have been evaluated for an association with increased breast cancer risk. We also summarize the current knowledge regarding the role of steroid receptors in mediating the carcinogenic effects of hormones used in menopausal hormone therapy, with special emphasis on the influence of the interplay or crosstalk between steroid receptors. Unraveling the intertwined nature of steroid hormone receptor signaling pathways in breast cancer biology is of utmost importance, considering that breast cancer is the most prevalent cancer among women worldwide. Moreover, understanding these mechanisms may reveal novel prevention or treatment options, and lead to the development of new hormone therapies that does not cause increased breast cancer risk.

A comparative characterization of estrogens used in hormone therapy via estrogen receptor (ER)-α and -ß.

Conventional hormone therapy (HT) containing estrogens such as ethinylestradiol (EE) have been associated with an increased risk of breast cancer and cardiovascular disease resulting in women seeking safer alternatives that are claimed to have fewer health risks. One such alternative gaining popularity, is custom-compounded bioidentical (b)HT formulations containing bioidentical estradiol (bE2) and estriol (bE3). However, the preparation of these custom-compounded estrogens is not regulated, and depending on the route of synthesis, steroid mixtures with differing activities may be produced. Thus, an investigation into the activities of estrogens prepared by custom-compounded pharmacies is warranted. The aim of this study was therefore to directly compare the pharmacological properties of bE2 and bE3 of unknown purity relative to commercially available, pure E2, E3 and estrone (E1) standards as well as synthetic EE used in conventional HT via the human estrogen receptor (ER)-α and -ß. We determined precise equilibrium dissociation constants (Kd or Ki values) and showed that bE2 and bE3 display similar binding affinities to the E2 and E3 standards, while EE had a higher affinity for ERα, and E1 a lower affinity for ERß. Furthermore, all the estrogens display similar agonist efficacies, but not potencies, for transactivation on a minimal ERE-containing promoter via the individual ER subtypes. Although E2 and E3 were equally efficacious and potent on the endogenous ERE-containing pS2 promoter in the MCF-7 BUS breast cancer cell line co-expressing ERα and ERß, E1 was less efficacious and potent than E2. This study is the first to demonstrate that the bioidentical estrogens, commercially available estrogen standards and synthetic EE are full agonists for transrepression on both minimal and endogenous NFκB-containing promoters. Moreover, we showed that these estrogens all increase proliferation and anchorage-independent growth of MCF-7 BUS cells to a similar extent, suggesting that custom-compounded bHT may in fact not be a safer alternative to conventional HT. Furthermore, our results showing that E3 and E1 are not weak estrogens, and that E3 does not antagonize the activity of E2, suggest that the rationale behind the use of E3 and E1 in custom-compounded bHT formulations should be readdressed. Taken together, the results indicating that there is mostly no difference between the custom-compounded bioidentical estrogens, commercially available estrogen standards and synthetic EE, at concentrations reflecting serum levels in women using estrogen-containing HT, suggest that there is no clear advantage in choosing bHT above conventional HT.

Comparing the androgenic and estrogenic properties of progestins used in contraception and hormone therapy.

Progestins used in endocrine therapies bind to multiple steroid receptors and are associated with several side-effects. It is thus important to understand the relationship between steroid receptor cross-reactivity and the side-effect profile of progestins. In cell lines that express negligible levels of steroid receptors, we report for the first time the binding affinities, potencies and efficacies of selected progestins from different generations determined in parallel. We show that the progestins bind to the androgen receptor (AR) with similar affinities to each other and progesterone, while none bind estrogen receptor (ER)-ß, and only norethisterone acetate, levonorgestrel and gestodene bind ERα. Comparative dose-response analysis revealed that progestins from the first three generations display similar androgenic activity to the natural androgen dihydrotestosterone for transactivation, while norethisterone acetate, levonorgestrel and gestodene are ERα agonists. We show for the first time that the anti-androgenic properties of progesterone and drospirenone are similar to the well-known AR antagonist hydroxyflutamide, while nomegestrol acetate is more potent and nestorone less potent than both hydroxyflutamide and progesterone. Moreover, we are the first to report that the older progestins, unlike progesterone and the fourth generation progestins, are efficacious ERα agonists for transrepression, while the selected progestins from the second and third generation are efficacious AR agonists for transrepression. Considering the progestin potencies and their reported free serum concentrations relative to dihydrotestosterone and estradiol, our results suggest that the progestins are likely to exert AR-, but not ERα- or ERß-mediated effects in vivo.

Fourth-Generation Progestins Inhibit 3ß-Hydroxysteroid Dehydrogenase Type 2 and Modulate the Biosynthesis of Endogenous Steroids.

Progestins used in contraception and hormone replacement therapy are synthetic compounds designed to mimic the actions of the natural hormone progesterone and are classed into four consecutive generations. The biological actions of progestins are primarily determined by their interactions with steroid receptors, and factors such as metabolism, pharmacokinetics, bioavailability and the regulation of endogenous steroid hormone biosynthesis are often overlooked. Although some studies have investigated the effects of select progestins on a few steroidogenic enzymes, studies comparing the effects of progestins from different generations are lacking. This study therefore explored the putative modulatory effects of progestins on de novo steroid synthesis in the adrenal by comparing the effects of select progestins from the respective generations, on endogenous steroid hormone production by the H295R human adrenocortical carcinoma cell line. Ultra-performance liquid chromatography/tandem mass spectrometry analysis showed that the fourth-generation progestins, nestorone (NES), nomegestrol acetate (NoMAC) and drospirenone (DRSP), unlike the progestins selected from the first three generations, modulate the biosynthesis of several endogenous steroids. Subsequent assays performed in COS-1 cells expressing human 3ßHSD2, suggest that these progestins modulate the biosynthesis of steroid hormones by inhibiting the activity of 3ßHSD2. The Ki values determined for the inhibition of human 3ßHSD2 by NES (9.5 ± 0.96 nM), NoMAC (29 ± 7.1 nM) and DRSP (232 ± 38 nM) were within the reported concentration ranges for the contraceptive use of these progestins in vivo. Taken together, our results suggest that newer, fourth-generation progestins may exert both positive and negative physiological effects via the modulation of endogenous steroid hormone biosynthesis.

11-Ketotestosterone and 11-Ketodihydrotestosterone in Castration Resistant Prostate Cancer: Potent Androgens Which Can No Longer Be Ignored.

Dihydrotestosterone (DHT) is regarded as the most potent natural androgen and is implicated in the development and progression of castration resistant prostate cancer (CRPC). Under castrate conditions, DHT is produced from the metabolism of the adrenal androgen precursors, DHEA and androstenedione. Recent studies have shown that the adrenal steroid 11ß-hydroxyandrostenedione (11OHA4) serves as the precursor to the androgens 11-ketotestosterone (11KT) and 11-ketodihydrotestosterone (11KDHT). In this study we comprehensively assess the androgenic activity of 11KT and 11KDHT. This is the first study, to our knowledge, to show that 11KT and 11KDHT, like T and DHT, are potent and efficacious agonists of the human androgen receptor (AR) and induced both the expression of representative AR-regulated genes as well as cellular proliferation in the androgen dependent prostate cancer cell lines, LNCaP and VCaP. Proteomic analysis revealed that 11KDHT regulated the expression of more AR-regulated proteins than DHT in VCaP cells, while in vitro conversion assays showed that 11KT and 11KDHT are metabolized at a significantly lower rate in both LNCaP and VCaP cells when compared to T and DHT, respectively. Our findings show that 11KT and 11KDHT are bona fide androgens capable of inducing androgen-dependant gene expression and cell growth, and that these steroids have the potential to remain active longer than T and DHT due to the decreased rate at which they are metabolised. Collectively, our data demonstrates that 11KT and 11KDHT likely play a vital, but overlooked, role in the development and progression of CRPC.

Interventions for Childhood Obesity in the First 1,000 Days A Systematic Review.

CONTEXT: The "first 1,000 days"-conception through age 24 months-are critical for the development and prevention of childhood obesity. This study systematically reviews existing and ongoing interventions during this period, identifies gaps in current research, and discusses conceptual frameworks and opportunities for future interventions. EVIDENCE ACQUISITION: PubMed, Embase, Web of Science, and ClinicalTrials.gov were searched to identify completed and ongoing interventions implemented during pregnancy through age 24 months that aimed to prevent overweight/obesity between ages 6 months and 18 years. English-language, controlled interventions published between January 1, 1980 and December 12, 2014, were analyzed between December 13, 2014 and March 15, 2015. EVIDENCE SYNTHESIS: Of 34 completed studies from 26 unique identified interventions, nine were effective. Effective interventions focused on individual- or family-level behavior changes through home visits, individual counseling or group sessions in clinical settings, a combination of home and group visits in a community setting, and using hydrolyzed protein formula. Protein-enriched formula increased childhood obesity risk. Forty-seven ongoing interventions were identified. Across completed and ongoing interventions, the majority target individual- or family-level changes, many are conducted in clinical settings, and few target early-life systems and policies that may impact childhood obesity. CONCLUSIONS: Obesity interventions may have the greatest preventive effect if begun early in life. Yet, few effective interventions in the first 1,000 days exist, and many target individual-level behaviors of parents and infants. Interventions that operate at systems levels and are grounded in salient conceptual frameworks hold promise for improving future models of early-life obesity prevention.

Risk Factors for Childhood Obesity in the First 1,000 Days: A Systematic Review.

CONTEXT: Mounting evidence suggests that the origins of childhood obesity and related disparities can be found as early as the "first 1,000 days"-the period from conception to age 2 years. The main goal of this study is to systematically review existing evidence for modifiable childhood obesity risk factors present from conception to age 2 years. EVIDENCE ACQUISITION: PubMed, Embase, and Web of Science were searched for studies published between January 1, 1980, and December 12, 2014, of childhood obesity risk factors present during the first 1,000 days. Prospective, original human subject, English-language research with exposure occurrence during the first 1,000 days and with the outcome of childhood overweight or obesity (BMI ≥85th percentile for age and sex) collected between age 6 months and 18 years were analyzed between December 13, 2014, and March 15, 2015. EVIDENCE SYNTHESIS: Of 5,952 identified citations, 282 studies met inclusion criteria. Several risk factors during the first 1,000 days were consistently associated with later childhood obesity. These included higher maternal pre-pregnancy BMI, prenatal tobacco exposure, maternal excess gestational weight gain, high infant birth weight, and accelerated infant weight gain. Fewer studies also supported gestational diabetes, child care attendance, low strength of maternal-infant relationship, low SES, curtailed infant sleep, inappropriate bottle use, introduction of solid food intake before age 4 months, and infant antibiotic exposure as risk factors for childhood obesity. CONCLUSIONS: Modifiable risk factors in the first 1,000 days can inform future research and policy priorities and intervention efforts to prevent childhood obesity.

The Influence of Antenatal Partner Support on Pregnancy Outcomes.

BACKGROUND: While there has been considerable attention given to the multitude of maternal factors that contribute to perinatal conditions and poor birth outcomes, few studies have aimed to understand the impact of fathers or partners. We examined associations of antenatal partner support with psychological variables, smoking behavior, and pregnancy outcomes in two socioeconomically distinct prebirth cohorts. MATERIALS AND METHODS: Data were from 1764 women recruited from an urban-suburban group practice (Project Viva) and 877 women from urban community health centers (Project ACCESS), both in the Boston area. Antenatal partner support was assessed by the Turner Support Scale. Multivariable linear and logistic regression analyses determined the impact of low antenatal partner support on the outcomes of interest. RESULTS: In early pregnancy, 6.4% of Viva and 23.0% of ACCESS participants reported low partner support. After adjustment, low partner support was cross-sectionally associated with high pregnancy-related anxiety in both cohorts (Viva AOR 1.8; 95% CI: 1.0-3.4 and ACCESS AOR 1.9; 95% CI: 1.1-3.3) and with depression in ACCESS (AOR 1.9; 95% CI: 1.1-3.3). In Viva, low partner support was also related to depression mid-pregnancy (AOR 3.1; 95% CI: 1.7-5.7) and to smoking (AOR 2.2; 95% CI: 1.3-3.8). Birth weight, gestational age, and fetal growth were not associated with partner support. CONCLUSIONS: This study of two economically and ethnically distinct cohorts in the Boston area highlights higher levels of antenatal anxiety, depression, and smoking among pregnant women who report low partner support. Partner support may be an important and potentially modifiable target for interventions to improve pregnancy outcomes.

Very low maternal lead level in pregnancy and birth outcomes in an eastern Massachusetts population.

PURPOSE: Maternal lead exposure is associated with poor birth outcomes in populations with moderate to high blood levels. However, no studies have looked at exposure levels commonly experienced by US women. METHODS: We evaluated the relationship between maternal red blood cell (RBC) lead levels in midpregnancy and birth outcomes in 949 mother-child pairs in a prebirth cohort. We used multiple linear regression and logistic regression, adjusted for potential confounders including maternal age, race, prepregnancy body mass index, and smoking to relate maternal lead to infant birth size and risk for preterm birth (<37 weeks). RESULTS: Mean RBC lead level was 1.2 µg/dL (range, 0.0-5.0). Mean (standard deviation) birthweight was 3505 (520) g, birthweight for gestational age z-score 0.22 (0.93), and length of gestation 39.5 (1.7) weeks. Mothers in the highest versus lowest lead quartile did not have higher odds (OR, 1.85; 95% confidence interval [CI], 0.79-4.34) of preterm delivery; after stratifying by child sex, there was an association among males (OR, 5.51; 95% CI, 1.21-25.15) but not females (OR, 0.82; 95% CI, 0.24-2.85). Maternal RBC lead was not associated with any continuous outcomes in combined or sex-stratified analyses. CONCLUSIONS: Maternal lead exposure, even at very low levels, may adversely affect some childbirth outcomes, particularly preterm birth among males.