TRPS1 regulates oestrogen receptor binding and histone acetylation at enhancers.

The chromatin state is finely tuned to regulate function and specificity for transcription factors such as oestrogen receptor alpha (ER), which contributes to cell growth in breast cancer. ER transcriptional potential is mediated, in large part, by the specific associated proteins and co-factors that interact with it. Despite the identification and characterisation of several ER coregulators, a complete and systematic view of ER-regulating chromatin modifiers is lacking. By exploiting a focused siRNA screen that investigated the requirement for a library of 330 chromatin regulators in ER-mediated cell growth, we find that the NuRD and coREST histone deacetylation complexes are critical for breast cancer cell proliferation. Further, by proteomic and genomics approaches, we discover the transcription factor TRPS1 to be a key interactor of the NuRD and coREST complexes. Interestingly, TRPS1 gene amplification occurs in 28% of human breast tumours and is associated with poor prognosis. We propose that TRPS1 is required to repress spurious binding of ER, where it contributes to the removal of histone acetylation. Our data suggest that TRPS1 is an important ER-associated transcriptional repressor that regulates cell proliferation, chromatin acetylation and ER binding at the chromatin of cis-regulatory elements.

Cell cycle-coupled expansion of AR activity promotes cancer progression.

The androgen receptor (AR) is required for prostate cancer (PCa) survival and progression, and ablation of AR activity is the first line of therapeutic intervention for disseminated disease. While initially effective, recurrent tumors ultimately arise for which there is no durable cure. Despite the dependence of PCa on AR activity throughout the course of disease, delineation of the AR-dependent transcriptional network that governs disease progression remains elusive, and the function of AR in mitotically active cells is not well understood. Analyzing AR activity as a function of cell cycle revealed an unexpected and highly expanded repertoire of AR-regulated gene networks in actively cycling cells. New AR functions segregated into two major clusters: those that are specific to cycling cells and retained throughout the mitotic cell cycle ('Cell Cycle Common'), versus those that were specifically enriched in a subset of cell cycle phases ('Phase Restricted'). Further analyses identified previously unrecognized AR functions in major pathways associated with clinical PCa progression. Illustrating the impact of these unmasked AR-driven pathways, dihydroceramide desaturase 1 was identified as an AR-regulated gene in mitotically active cells that promoted pro-metastatic phenotypes, and in advanced PCa proved to be highly associated with development of metastases, recurrence after therapeutic intervention and reduced overall survival. Taken together, these findings delineate AR function in mitotically active tumor cells, thus providing critical insight into the molecular basis by which AR promotes development of lethal PCa and nominate new avenues for therapeutic intervention.

Mechanisms of oestrogen receptor (ER) gene regulation in breast cancer.

Most breast cancers are driven by a transcription factor called oestrogen receptor (ER). Understanding the mechanisms of ER activity in breast cancer has been a major research interest and recent genomic advances have revealed extraordinary insights into how ER mediates gene transcription and what occurs during endocrine resistance. This review discusses our current understanding on ER activity, with an emphasis on several evolving, but important areas of ER biology.

Genomic interaction between ER and HMGB2 identifies DDX18 as a novel driver of endocrine resistance in breast cancer cells.

Breast cancer resistance to endocrine therapies such as tamoxifen and aromatase inhibitors is a significant clinical problem. Steroid receptor coactivator-1 (SRC-1), a coregulatory protein of the oestrogen receptor (ER), has previously been shown to have a significant role in the progression of breast cancer. The chromatin protein high mobility group box 2 (HMGB2) was identified as an SRC-1 interacting protein in the endocrine-resistant setting. We investigated the expression of HMGB2 in a cohort of 1068 breast cancer patients and found an association with increased disease-free survival time in patients treated with endocrine therapy. However, it was also verified that HMGB2 expression could be switched on in endocrine-resistant tumours from breast cancer patients. To explore the function of this poorly characterized protein, we performed HMGB2 ChIPseq and found distinct binding patterns between the two contexts. In the resistant setting, the HMGB2, SRC-1 and ER complex are enriched at promoter regions of target genes, with bioinformatic analysis indicating a switch in binding partners between the sensitive and resistant phenotypes. Integration of binding and gene expression data reveals a concise set of target genes of this complex including the RNA helicase DDX18. Modulation of DDX18 directly affects growth of tamoxifen-resistant cells, suggesting that it may be a critical downstream effector of the HMGB2:ER complex. This study defines HMGB2 interactions with the ER complex at specific target genes in the tamoxifen-resistant setting.

Estrogen and antiestrogen regulation of cell cycle progression in breast cancer cells.

The central involvement of estrogen in the development of the mammary gland and in the genesis of breast cancer has lent impetus to studies of the links between estrogen action and the cell cycle machinery. Recent studies of the estrogenic regulation of molecules with known roles in the control of G1/S phase progression have resulted in significant advances in understanding these links. Estrogens independently regulate the expression and function of c-Myc and cyclin D1 and the induction of either c-Myc or cyclin D1 is sufficient to recapitulate the effects of estrogen on cell cycle progression. These pathways converge at the activation of cyclin E-Cdk2 complexes. The active cyclin E-Cdk2 complexes are depleted of the cyclin dependent kinase (CDK) inhibitor p21(WAF1/CIP1) because of estrogen-mediated inhibition of nascent p21(WAF1/CIP1). Insulin and estrogen synergistically stimulate cell cycle progression, and the ability of estrogen to antagonize an insulin-induced increase in p21(WAF1/CIP1) gene expression appears to underlie this effect. Antiestrogen treatment of MCF-7 cells leads to an acute decrease of c-Myc expression, a subsequent decline in cyclin D1, and ultimately arrest of cells in a state with features characteristic of quiescence. An antisense-mediated decrease in c-Myc expression results in decreased cyclin D1 expression and inhibition of DNA synthesis, mimicking the effects of antiestrogen treatment and emphasizing the importance of c-Myc as an estrogen/antiestrogen target. These data identify c-Myc, cyclin D1, p21(WAF1/CIP1) and cyclin E-Cdk2 as central components of estrogen regulation of cell cycle progression and hence as potential downstream targets that contribute to the role of estrogen in oncogenesis.

The effect of droloxifene and estrogen on thyroid function in postmenopausal women.

Estrogen is known to increase serum T4-binding globulin (TBG) concentrations, thereby increasing serum total T4 concentrations. Serum free T4 concentrations, however, remain normal. Tamoxifen, a selective estrogen receptor modifier (SERM), also raises serum TBG concentrations, but whether newer SERMs with less stimulatory action on the endometrium do so is not known. We, therefore, compared the effect of droloxifene, a SERM, and conjugated equine estrogen on pituitary-thyroid function in normal postmenopausal women. Ten women were treated for 6 weeks with conjugated estrogen (Premarin), 0.625 mg/day, and droloxifene, 60 mg/day, in a double-blind crossover study with an intervening 4-week no-treatment period. We measured serum T4, T3, TBG, free T4 index, and TSH at baseline and at the end of each 6-week period. The baseline values were compared with the 6-week values using paired t tests. The mean (+/- SD) serum TBG concentrations increased significantly during both treatment periods (baseline, 1.5+/-0.4 mg/dL; conjugated estrogens, 2.7+/-0.6 mg/dL; droloxifene, 2.1+/-0.6 mg/dL; P < 0.001 and P = 0.001, respectively). There were no significant changes in the serum free T4 index. Serum T4 and T3 concentrations increased during both treatment periods, however, the increase was significant only for T4 during the conjugated estrogen treatment period. The serum TSH concentrations increased significantly during both treatment periods (18% during conjugated estrogen and 11% during droloxifene), and the values remained within the normal range in all women. Administration of both conjugated estrogen and droloxifene for 6 weeks increases serum TSH and TBG concentrations, but does not alter free T4 index values in postmenopausal women.

A method for checking interobserver reliability in observational sleep studies.

Disturbances of the sleep/wake cycle occur frequently in nursing home residents. Because of the many technical difficulties in studying sleep and rhythms in such patients, systematic behavioral observations offer an alternative approach. In this study we describe a method for determining interrater reliability of such observations. Two individuals observed 39 nursing home residents four times per hour during daytime and nighttime hours. Results indicated high interrater reliability for both sleep/wake and the presence of apnea during sleep. Both day and night observations were made reliably. We found only 101 discrepancies of 1.160 tandem observations. These results suggests that behavioral observations are a viable approach in the study of the sleep/wake cycle in nursing home settings.

Correlation between the glucose clamp technique and the homeostasis model assessment in hypertension.

The homeostasis model assessment (HOMA) has been extensively used as a reliable surrogate marker for measuring insulin resistance in patients with diabetes mellitus and in normal subjects. Comparative data in another insulin resistance state, hypertension, is lacking. The goal of the present study was to obtain that information by testing the correlation of HOMA with the euglycemic hyperinsulinemic clamp in 36 hypertensive and 27 normotensive subjects. Clamp-derived insulin sensitivity was calculated as the glucose disposal rate over steady-state plasma insulin concentration. Homeostasis model assessment was computed using the formula (fasting glucose x fasting insulin)/22.5. There was significant correlation between the clamp and HOMA for both the hypertensive (r = -0.64, P < .0001) and normotensive subjects (r = -0.58, P = .002). The HOMA can be used reliably as a less expensive and less cumbersome alternative for measuring insulin resistance in hypertension.

Higher cholesterol and insulin levels in pregnancy are associated with increased risk for pregnancy-induced hypertension.

Hyperinsulinemia and dyslipidemia are known to be associated with essential hypertension but their role in pregnancy-induced hypertension remains unclear. We performed a case-control study comparing cholesterol, insulin, and glucose levels in the early third trimester of pregnancy among 31 women who developed pregnancy-induced hypertension (PIH) (either preeclampsia [n = 6] or nonproteinuric gestational hypertension [n = 25]), with 31 women remaining normotensive through pregnancy. As compared with women remaining normotensive, women subsequently developing PIH had higher fasting cholesterol levels (279 v 247 mg/dL; P = .02) and higher fasting insulin levels (13.3 v 7.9 microU/mL; P = .03), although fasting glucose levels and levels of glucose and insulin after glucose load did not differ significantly between groups. In comparing hypertensive subgroups, fasting insulin levels were significantly higher among women who subsequently developed preeclampsia, but not among those subsequently developing nonproteinuric gestational hypertension. Although women developing PIH had higher pregravid body mass index (25.1 v 22.6 kg/m2, P = .06), fasting cholesterol and insulin levels were associated with risk for PIH even after adjustment for body mass index and age (relative risks for one unit increase, respectively: 1.02 (P = .03) and 1.12 (P = .03). Higher fasting cholesterol and insulin levels in mid- to late pregnancy are associated with increased risk for PIH. These observations support a role for insulin resistance in the development of this complication of pregnancy.

Redirecting traditional professional values to support safety: changing organisational culture in health care.

Professionals in healthcare organisations who seek to enhance safety and quality in an increasingly demanding industry environment often identify culture as a barrier to change. The cultural focus on individual autonomy, for example, seems to conflict with desired norms of teamwork, problem reporting, and learning. We offer a definition and explication of why culture is important to change efforts. A cultural analysis of health care suggests professional values that can be redirected to support change. We offer examples of organisations that drew upon cultural strengths to create new ways of working and gradually shifted the culture.

Leading organisational learning in health care.

As healthcare organisations seek to enhance safety and quality in a changing environment, organisational learning practices can help to improve existing skills and knowledge and provide opportunities to discover better ways of working together. Leadership at executive, middle management, and local levels is needed to create a sense of shared purpose. This shared vision should help to build effective relationships, facilitate connections between action and reflection, and strengthen the desirable elements of the healthcare culture while modifying outdated assumptions, procedures, and structures.

Lessons learned from non-medical industries: root cause analysis as culture change at a chemical plant.

Root cause analysis was introduced to a chemical plant as a way of enhancing performance and safety, exemplified by the investigation of an explosion. The cultural legacy of the root cause learning intervention was embodied in managers' increased openness to new ideas, individuals' questioning attitude and disciplined thinking, and a root cause analysis process that provided continual opportunities to learn and improve. Lessons for health care are discussed, taking account of differences between the chemical and healthcare industries.

Digitalis-like factor response to hyperinsulinemia accompanying a euglycemic hyperinsulinemic clamp or oral glucose tolerance test.

Many studies of essential hypertension find evidence of insulin resistance in the same individuals, leading some to postulate a hypertensive role for insulin. However, the mechanisms by which insulin might exert a hypertensive effect are not fully resolved. An endogenous sodium pump inhibitor or digitalis-like factor (DLF) has been proposed as a hypertensive agent and its plasma concentrations are elevated in hypertension and in Type II diabetes, where insulin levels are elevated. Hence, we studied the effect of insulin on DLF using two approaches to achieve hyperinsulinemia. Normotensive men and women underwent a hyperinsulinemic, euglycemic clamp (40 mU/m2/min insulin, 40 mU = 1.6 x 10(-6) g) in which plasma insulin concentration was kept at high, but physiologic levels. Serum DLF (measured as inhibition of [Na,K]ATPase activity) and insulin levels were measured at baseline and every 30 min throughout the 2 hr clamp. Additionally, other subjects underwent an oral glucose tolerance test (OGTT) as a second means of increasing insulin levels. Insulin and DLF levels were measured prior to and hourly for 3 hours after receiving 100 gm of oral glucose. Serum DLF increased significantly during the clamp from a baseline of 4.6 +/- 0.81 to a peak of 8.7 +/- 1.2% inhibition (p=0.001). Comparison of the baseline and peak DLF levels with concomitant plasma insulin levels revealed a significant correlation (R=0.60, p=0.003). During the OGTT, DLF levels rose from a baseline of 2.4 +/- 1.0 to a peak level of 5.0 +/- 0.4%, p = 0.04. These results suggest that DLF, a factor that can cause vascular smooth muscle contraction and potentially influence blood pressure, is increased by hyperinsulinemia and provides a mechanism by which insulin may increase blood pressure.

Sentencing goals, causal attributions, ideology, and personality.

Disparity in sentencing of criminals has been related to a variety of individual difference variables. We propose a framework establishing resonances or coherent patterns among sentencing goals, causal attributions, ideology, and personality. Two studies are described, one with law and criminology students, the other with probation officers. Relations among the different types of variables reveal two resonances among both students and officers. One comprises various conservative and moralistic elements: a tough, punitive stance toward crime; belief in individual causality for crime; high scores on authoritarianism, dogmatism, and internal locus of control; lower moral stage; and political conservatism. The second comprises various liberal elements: rehabilitation, belief in economic and other external determinants of crime, higher moral stage, and belief in the powers and responsibilities of government to correct social problems. Implications of these results are discussed for individual differences in sentencing, attribution theory, and attempts to reduce disparity.

Sleep and "sundowning" in nursing home patients with dementia.

"Sundowning," a term that is sometimes equated with sleep disturbance or nocturnal delirium in dementia, is a poorly understood psychiatric phenomenon. In this study, we performed systematic, temporally specific, behavioral observations of nine profoundly demented nursing home patients 4 times an hour over a 12-hour period (1300 to 0100h) to determine whether their agitation was more likely to occur at a particular time of day. Results indicated only equivocal evidence that agitation was any worse nocturnally or during the time near sunset, thus raising the possibility that at least some components of sundowning may reflect disruptive behaviors occurring with identical frequency throughout the day but with differential impact upon nursing staff. Additional data indicated that awakening from sleep during darkness was also associated with agitation. A final result was a trend indicating the apparent worsening of agitation seasonally (greater agitation during winter), which may suggest involvement of the circadian timing system.

Elevated levels of FOXA1 facilitate androgen receptor chromatin binding resulting in a CRPC-like phenotype.

Castration-resistant prostate cancer (CRPC) continues to pose a significant clinical challenge with new generation second-line hormonal therapies affording limited improvement in disease outcome. As the androgen receptor (AR) remains a critical driver in CRPC, understanding the determinants of its transcriptional activity is important for developing new AR-targeted therapies. FOXA1 is a key component of the AR transcriptional complex yet its role in prostate cancer progression and the relationship between AR and FOXA1 are not completely resolved. It is well established that FOXA1 levels are elevated in advanced prostate cancer and metastases. We mimicked these conditions by overexpressing FOXA1 in the androgen-responsive LNCaP prostate cancer cell line and observed a significant increase in AR genomic binding at novel regions that possess increased chromatin accessibility. High levels of FOXA1 resulted in increased proliferation at both sub-optimal and high 5α-dihydrotestosterone (DHT) concentrations. Immunohistochemical staining for FOXA1 in a clinical prostate cancer cohort revealed that high FOXA1 expression is associated with shorter time to biochemical recurrence after radical prostatectomy (hazard ratio (HR) 5.0, 95% confidence interval (CI) 1.2-21.1, P=0.028), positive surgical margins and higher stage disease at diagnosis. The gene expression program that results from FOXA1 overexpression is enriched for PTEN, Wnt and other pathways typically represented in CRPC gene signatures. Together, these results suggest that in an androgen-depleted state, elevated levels of FOXA1 enhance AR binding at genomic regions not normally occupied by AR, which in turn facilitates prostate cancer cell growth.

Minireview: The androgen receptor in breast tissues: growth inhibitor, tumor suppressor, oncogene?

Androgen receptor (AR) signaling exerts an antiestrogenic, growth-inhibitory influence in normal breast tissue, and this role may be sustained in estrogen receptor α (ERα)-positive luminal breast cancers. Conversely, AR signaling may promote growth of a subset of ERα-negative, AR-positive breast cancers with a molecular apocrine phenotype. Understanding the molecular mechanisms whereby androgens can elicit distinct gene expression programs and opposing proliferative responses in these two breast cancer phenotypes is critical to the development of new therapeutic strategies to target the AR in breast cancer.