Regulation of mineralocorticoid receptor activation by circadian protein TIMELESS.

The mineralocorticoid receptor (MR) is a ligand-activated transcription factor that regulates cardiorenal physiology and disease. Ligand-dependent MR transactivation involves a conformational change in the MR and recruitment of coregulatory proteins to form a unique DNA-binding complex at the hormone response element in target gene promoters. Differences in the recruitment of coregulatory proteins can promote tissue-, ligand- or gene-specific transcriptional outputs. The goal of this study was to evaluate the circadian protein TIMELESS as a selective regulator of MR transactivation. TIMELESS has an established role in cell cycle regulation and DNA repair. TIMELESS may not be central to mammalian clock function and does not bind DNA; however, RNA and protein levels oscillate over 24 h. Co-expression of TIMELESS down-regulated MR transactivation of an MR-responsive reporter in HEK293 cells, yet enhanced transactivation mediated by other steroid receptors. TIMELESS markedly inhibited MR transactivation of synthetic and native gene promoters and expression of MR target genes in H9c2 cardiac myoblasts. Immunofluorescence showed aldosterone induces colocalisation of TIMELESS and MR, although a direct interaction was not confirmed by coimmunoprecipitation. Potential regulation of circadian clock targets cryptochrome 1 and 2 by TIMELESS was not detected. However, our data suggest that these effects may involve TIMELESS coactivation of oestrogen receptor alpha (ERα). Taken together, these data suggest that TIMELESS may contribute to MR transcriptional outputs via enhancing ERα inhibitory actions on MR transactivation. Given the variable expression of TIMELESS in different cell types, these data offer new opportunities for the development of MR modulators with selective actions.

Mineralocorticoid receptor actions in cardiovascular development and disease.

Mineralocorticoid receptors (MRs) are transcriptional regulators that mediate the diverse physiological and pathophysiological actions of corticosteroid hormones across many tissues. In the kidney aldosterone control of sodium/water resorption via DNA-binding actions of the MR is established. MRs also regulate tissues not involved in electrolyte homeostasis such as the heart, adipose tissue, brain, and inflammatory cells where the MRs can respond to both aldosterone and cortisol. The pathology of inappropriate MR activation in non-epithelial tissues are well-described, and steroidal antagonists of the MR have been clinically beneficial in the management of heart failure and blood pressure for decades. However, the role of cortisol-dependent MR activation in the physiological setting is less well defined. Like other steroid hormone receptors, the MR also regulates non-DNA-binding pathways including MAPK pathways and G protein coupled receptors to provide diversity to MR signaling. Whether nonDNA binding pathways are more relevant for MR activation in non-epithelial, versus epithelial, tissues remain unclear. This review will focus on molecular regulation of ligand-dependent MR activation and the physiology and pathophysiology of MR actions in the heart with a focus on the cardiomyocyte and provide a discussion of relevant genomic and non-genomic MR pathways and potential new transcriptional partners for the MR and their relevance for health and disease. Understanding MR actions in the heart will provide new insights into cell-selective mechanisms that underpin the therapeutic benefits of MRAs, and are a critical step towards developing next-generation tissue selective MR modulators with improved safety profiles.

A tumour suppressive relationship between mineralocorticoid and retinoic acid receptors activates a transcriptional program consistent with a reverse Warburg effect in breast cancer.

BACKGROUND: The role of nuclear receptors in both the aetiology and treatment of breast cancer is exemplified by the use of the oestrogen receptor (ER) as a prognostic marker and treatment target. Treatments targeting the oestrogen signalling pathway are initially highly effective for most patients. However, for the breast cancers that fail to respond, or become resistant, to current endocrine treatments, the long-term outlook is poor. ER is a member of the nuclear receptor superfamily, comprising 48 members in the human, many of which are expressed in the breast and could be used as alternative targets in cases where current treatments are ineffective. METHODS: We used sparse canonical correlation analysis to interrogate potential novel nuclear receptor expression relationships in normal breast and breast cancer. These were further explored using whole transcriptome profiling in breast cancer cells after combinations of ligand treatments. RESULTS: Using this approach, we discovered a tumour suppressive relationship between the mineralocorticoid receptor (MR) and retinoic acid receptors (RAR), in particular RARß. Expression profiling of MR expressing breast cancer cells revealed that mineralocorticoid and retinoid co-treatment activated an expression program consistent with a reverse Warburg effect and growth inhibition, which was not observed with either ligand alone. Moreover, high expression of both MR and RARB was associated with improved breast cancer-specific survival. CONCLUSION: Our study reveals a previously unknown relationship between MR and RAR in the breast, which is dependent on menopausal state and altered in malignancy. This finding identifies potential new targets for the treatment of breast cancers that are refractory to existing therapeutic options.

Endocrine aspects of ACE2 regulation: RAAS, steroid hormones and SARS-CoV-2.

Coronavirus disease (COVID-19) is caused by a new strain of coronavirus, the severe acute respiratory syndrome coronavirus 2 or SARS-CoV-2. At the time of writing, SARS-CoV-2 has infected over 5 million people worldwide. A key step in understanding the pathobiology of the SARS-CoV-2 was the identification of -converting enzyme 2 (ACE2) as the receptor for SARS-CoV-2 to gain entry into host cells. ACE2 is an established component of the 'protective arm' of the renin-angiotensin-aldosterone-system (RAAS) that opposes ACE/angiotensin II (ANG II) pressor and tissue remodelling actions. Identification of ACE2 as the entry point for SARS-CoV-2 into cells quickly focused attention on the use of ACE inhibitors (ACEi), angiotensin receptor blockers (ARB) and mineralocorticoid receptor antagonists (MRA) in patients with hypertension and cardiovascular disease given that these pharmacological agents upregulate ACE2 expression in target cells. ACE2 is cleaved from the cells by metalloproteases ADAM10 and ADAM17. Steroid hormone receptors regulate multiple components of the RAAS and may contribute to the observed variation in the incidence of severe COVID-19 between men and women, and in patients with pre-existing endocrine-related disease. Moreover, glucocorticoids play a critical role in the acute and chronic management of inflammatory disease, independent of any effect on RAAS activity. Dexamethasone, a synthetic glucocorticoid, has emerged as a life-saving treatment in severe COVID-19. This review will examine the endocrine mechanisms that control ACE2 and discusses the impact of therapies targeting the RAAS, glucocorticoid and other endocrine systems for their relevance to the impact of SARS-CoV-2 infection and the treatment and recovery from COVID-19-related critical illness.

Cardiomyocyte transcription is controlled by combined MR and circadian clock signalling.

We previously identified a critical pathogenic role for MR activation in cardiomyocytes that included a potential interaction between the MR and the molecular circadian clock. While glucocorticoid regulation of the circadian clock is undisputed, MR interactions with circadian clock signalling are limited. We hypothesised that the MR influences cardiac circadian clock signalling, and vice versa. 10nM aldosterone or corticosterone regulated CRY 1, PER1, PER2 and ReverbA (NR1D1) gene expression patterns in H9c2 cells over 24hr. MR-dependent regulation of circadian gene promoters containing GREs and E-box sequences was established for CLOCK, Bmal, CRY 1 and CRY2, PER1 and PER2 and transcriptional activators CLOCK and Bmal modulated MR-dependent transcription of a subset of these promoters. We also demonstrated differential regulation of MR target gene expression in hearts of mice 4hr after administration of aldosterone at 8AM versus 8PM. Our data support combined MR regulation of a subset of circadian genes and that endogenous circadian transcription factors CLOCK and Bmal modulate this response. This unsuspected relationship links MR in the heart to circadian rhythmicity at the molecular level and has important implications for the biology of MR signalling in response to aldosterone as well as cortisol. These data are consistent with MR signalling in the brain where, like the heart, it preferentially responds to cortisol. Given the undisputed requirement for diurnal cortisol release in the entrainment of peripheral clocks, the present study highlights the MR as an important mechanism for transducing the circadian actions of cortisol in addition to the GR in the heart.

Lupeol, the major compound of the dichloromethane extract of Millettia macrophylla Benth (Fabaceae), displays estrogenic effects in ovariectomized rats.

The present work deals with the assessment of the in vitro and in vivo estrogenic effects of the triterpenoids (lupenone, lupeol, and stigmastenone) isolated from Millettia macrophylla extract. The in vitro estrogenicity was performed by a reporter gene assay and estrogen receptor-α (ERα) target gene expression, whereas the in vivo estrogenicity was evaluated by a 3-day uterotrophic assay in ovariectomized rats. As results, lupenone and lupeol did not transactivate ERα as well as ERß of human embryonic kidney 293T (HEK293T) cells. However, lupeol seems to be antagonistic to estrogen (E2) only in HEK293T-ERα (10-9 and 10-8  µM). Furthermore, lupeol slightly upregulated GREB1 gene expression at the concentration of 1 µM, suggesting a weak activation of endogenous ERα. In vivo, only lupeol at a dose of 1 mg/kg significantly increased the uterine wet weight (p < 0.05), uterine (p < 0.05), and vaginal (p < 0.01) epithelial heights. The concomitant administration of lupeol (1 mg/kg) with a pure antiestrogen fulvestrant abrogated its effects only in the vagina, whereas in combination with E2, lupeol exhibited a significant antiestrogen-like effect in uterine wet weight and synergistic effects on endometrium. Lupeol has estrogenic effects that is partly through ERs transcriptional activity and does involve alternative mechanisms that are still to be uncovered.

CTBP1/CYP19A1/estradiol axis together with adipose tissue impacts over prostate cancer growth associated to metabolic syndrome.

Metabolic syndrome (MeS) increases prostate cancer (PCa) risk and aggressiveness. C-terminal binding protein 1 (CTBP1) is a transcriptional co-repressor of tumor suppressor genes that is activated by low NAD+ /NADH ratio. Previously, our group established a MeS and PCa mice model that identified CTBP1 as a novel link associating both diseases. We found that CTBP1 controls the transcription of aromatase (CYP19A1), a key enzyme that converts androgens to estrogens. The aim of this work was to investigate the mechanism that explains CTBP1 as a link between MeS and PCa based on CYP19A1 and estrogen synthesis regulation using PCa cell lines, MeS/PCa mice and adipose co-culture systems. We found that CTBP1 and E1A binding protein p300 (EP300) bind to CYP19A1 promoter and downregulate its expression in PC3 cells. Estradiol, through estrogen receptor beta, released CTBP1 from CYP19A1 promoter triggering its transcription and modulating PCa cell proliferation. We generated NSG and C57BL/6J MeS mice by chronically feeding animals with high fat diet. In the NSG model, CTBP1 depleted PCa xenografts showed an increase in CYP19A1 expression with subsequent increment in intratumor estradiol concentrations. Additionally, in C57BL/6J mice, MeS induced hypertrophy, hyperplasia and inflammation of the white adipose tissue, which leads to a proinflammatory phenotype and increased serum estradiol concentration. Thus, MeS increased PCa growth and Ctbp1, Fabp4 and IL-6 expression levels. These results describe, for the first time, a novel CTBP1/CYP19A1/Estradiol axis that explains, in part, the mechanism for prostate tumor growth increase by MeS.

Timeless Is a Novel Estrogen Receptor Co-activator Involved in Multiple Signaling Pathways in MCF-7 Cells.

Activation of estrogen receptor α (ERα) stimulates cell division and tumor growth by modulating the expression of ERα target genes. This activation involves the recruitment of specific proteins with activities that are still not fully understood. Timeless, the human homolog of the Drosophila gene involved in circadian rhythm, was previously shown to be a strong predictor of tamoxifen relapse, and is involved in genomic stability and cell cycle control. In this study, we investigated the interplay between Timeless and ERα, and showed that human Timeless is an ERα coactivator. Timeless binds to ERα and enhances its transcriptional activity. Overexpressing Timeless increases PARP1 expression and enhances ERα-induced gene regulation through the proximal LXXLL motif on Timeless protein and ERα PARylation. Finally, Timeless is recruited with ERα on the GREB1 and cMyc promoters. These data, the first to link Timeless to steroid hormone function, provide a mechanistic basis for its clinical association with tamoxifen resistance. Thus, our results identify Timeless as another key regulator of ERα in controlling ERα transactivation.

LRH-1 expression patterns in breast cancer tissues are associated with tumour aggressiveness.

The significance and regulation of liver receptor homologue 1 (LRH-1, NR5A2), a tumour-promoting transcription factor in breast cancer cell lines, is unknown in clinical breast cancers. This study aims to determine LRH-1/NR5A2 expression in breast cancers and relationship with DNA methylation and tumour characteristics. In The Cancer Genome Atlas breast cancer cohort NR5A2 expression was positively associated with intragenic CpG island methylation (1.4-fold expression for fully methylated versus not fully methylated, p=0.01) and inversely associated with promoter CpG island methylation (0.6-fold expression for fully methylated versus not fully methylated, p=0.036). LRH-1 immunohistochemistry of 329 invasive carcinomas and ductal carcinoma in situ (DCIS) was performed. Densely punctate/coarsely granular nuclear reactivity was significantly associated with high tumour grade (p<0.005, p=0.033 in invasive carcinomas and DCIS respectively), negative estrogen receptor status (p=0.008, p=0.038 in overall cohort and invasive carcinomas, respectively), negative progesterone receptor status (p=0.003, p=0.013 in overall cohort and invasive carcinomas, respectively), HER2 amplification (overall cohort p=0.034) and non-luminal intrinsic subtype (p=0.018, p=0.038 in overall cohort and invasive carcinomas, respectively). These significant associations of LRH-1 protein expression with tumour phenotype suggest that LRH-1 is an important indicator of tumour biology in breast cancers and may be useful in risk stratification.

Deoxycorticosterone/Salt-Mediated Cardiac Inflammation and Fibrosis Are Dependent on Functional CLOCK Signaling in Male Mice.

Activation of the mineralocorticoid receptor (MR) promotes inflammation, fibrosis, and hypertension. Clinical and experimental studies show that MR antagonists have significant therapeutic benefit for all-cause heart failure; however, blockade of renal MRs limits their widespread use. Identification of key downstream signaling mechanisms for the MR in the cardiovascular system may enable development of targeted MR antagonists with selectivity for pathological MR signaling and lower impact on physiological renal electrolyte handling. One candidate pathway is the circadian clock, the dysregulation of which is associated with cardiovascular diseases. We have previously shown that the circadian gene Per2 is dysregulated in hearts with selective deletion of cardiomyocyte MR. We therefore investigated MR-mediated cardiac inflammation and fibrosis in mice that lack normal regulation and oscillation of the circadian clock in peripheral tissues, that is, CLOCKΔ19 mutant mice. The characteristic cardiac inflammatory/fibrotic response to a deoxycorticosterone (DOC)/salt for 8 weeks was significantly blunted in CLOCKΔ19 mice when compared with wild-type mice, despite a modest increase at "baseline" for fibrosis and macrophage number in CLOCKΔ19 mice. In contrast, cardiac hypertrophy in response to DOC/salt was significantly greater in CLOCKΔ19 vs wild-type mice. Markers for renal inflammation and fibrosis were similarly attenuated in the CLOCKΔ19 mice given DOC/salt. Moreover, increased CLOCK expression in H9c2 cardiac cells enhanced MR-mediated transactivation of Per1, suggesting cooperative signaling between these transcription factors. This study demonstrates that the full development of MR-mediated cardiac inflammation and fibrosis is dependent on intact signaling by the circadian protein CLOCK.

Estrogen-like and tissue-selective effects of 7-methoxycoumarin from Ficus umbellata (Moraceae): an in vitro and in vivo study.

BACKGROUND: Ficus umbellata is a medicinal plant previously shown to endow estrogenic properties. Its major component was isolated and characterized as 7-methoxycoumarin (MC). Noteworthy, coumarins and the respective active metabolite 7-hydroxycoumarin analogs have shown aromatase inhibitory activity, which is of particular interest in the treatment of estrogen-dependent cancers. The present work aimed at evaluating the estrogenic/antiestrogenic effects of MC in vitro and in vivo. METHODS: To do so, in vitro assays using E-screen and reporter gene were done. In vivo, a 3-day uterotrophic assay followed by a postmenopausal-like rat model to characterize MC as well as F. umbellata aqueous extract in ovariectomized Wistar rats was performed. The investigations focused on histological (vaginal and uterine epithelial height) and morphological (uterine wet weight, vagina stratification and cornification) endpoints, bone mass, biochemical parameters and lipid profile. RESULTS: MC induced a significant (p < 0.05) MCF-7 cell proliferation at a concentration of 0.1 µM, but did not inhibit the effect induced by estradiol in both E-screen and reporter gene assays. In vivo, MC treatment did not show an uterotrophic effect in both rat models used. However, MC (1 mg/kg) induced a significant increase (p < 0.01) of vaginal epithelial height. No significant change was observed with MC in abdominal fat weight, serum lipid levels and bone weight. CONCLUSION: These results suggest that MC has a weak estrogenic activity in vitro and in vivo that accounts only in part to the estrogenicity of the whole plant extract. MC could be beneficial with regard to vagina dryness as it showed a tissue specific effect without exposing the uterus to a potential tumorigenic growth.

The angiotensin receptor blocker, Losartan, inhibits mammary tumor development and progression to invasive carcinoma.

Drugs that target the Renin-Angiotensin System (RAS) have recently come into focus for their potential utility as cancer treatments. The use of Angiotensin Receptor Blockers (ARBs) and Angiotensin-Converting Enzyme (ACE) Inhibitors (ACEIs) to manage hypertension in cancer patients is correlated with improved survival outcomes for renal, prostate, breast and small cell lung cancer. Previous studies demonstrate that the Angiotensin Receptor Type I (AT1R) is linked to breast cancer pathogenesis, with unbiased analysis of gene-expression studies identifying significant up-regulation of AGTR1, the gene encoding AT1R in ER+ve/HER2-ve tumors correlating with poor prognosis. However, there is no evidence, so far, of the functional contribution of AT1R to breast tumorigenesis. We explored the potential therapeutic benefit of ARB in a carcinogen-induced mouse model of breast cancer and clarified the mechanisms associated with its success.Mammary tumors were induced with 7,12-dimethylbenz[α]antracene (DMBA) and medroxyprogesterone acetate (MPA) in female wild type mice and the effects of the ARB, Losartan treatment assessed in a preventative setting (n = 15 per group). Tumor histopathology was characterised by immunohistochemistry, real-time qPCR to detect gene expression signatures, and tumor cytokine levels measured with quantitative bioplex assays. AT1R was detected with radiolabelled ligand binding assays in fresh frozen tumor samples.We showed that therapeutic inhibition of AT1R, with Losartan, resulted in a significant reduction in tumor burden; and no mammary tumor incidence in 20% of animals. We observed a significant reduction in tumor progression from DCIS to invasive cancer with Losartan treatment. This was associated with reduced tumor cell proliferation and a significant reduction in IL-6, pSTAT3 and TNFα levels. Analysis of tumor immune cell infiltrates, however, demonstrated no significant differences in the recruitment of lymphocytes or tumour-associated macrophages in Losartan or vehicle-treated mammary tumors.Analysis of AT1R expression with radiolabelled ligand binding assays in human breast cancer biopsies showed high AT1R levels in 30% of invasive ductal carcinomas analysed. Furthermore, analysis of the TCGA database identified that high AT1R expression to be associated with luminal breast cancer subtype.Our in vivo data and analysis of human invasive ductal carcinoma samples identify the AT1R is a potential therapeutic target in breast cancer, with the availability of a range of well-tolerated inhibitors currently used in clinics. We describe a novel signalling pathway critical in breast tumorigenesis, that may provide new therapeutic avenues to complement current treatments.

Ethanol-extracted Cameroonian propolis exerts estrogenic effects and alleviates hot flushes in ovariectomized Wistar rats.

BACKGROUND: Since the biological properties of propolis depend to the plants that can be found in a specific region, propolis from unexplored regions attracts the attention of scientists. Ethanolic extract of Cameroonian propolis (EEP) is used to treat various ailments including gynecological problems and amenorrhea. Since there were no scientific data to support the above claims, the present study was therefore undertaken to assess estrogenic properties of Cameroonian propolis. METHODS: To achieve our goal, the ability of EEP to induce MCF-7 cells proliferation in E-screen assay as well as to activate estrogen receptors α (ERα) and ß (ERß) in cell-based reporter gene assays using human embryonic kidney cells (HEK293T) transfected with ERs was tested. Further, a 3-day uterotrophic assay was performed and the ability of EEP to alleviate hot flushes in ovariectomized adult rats was evaluated. RESULTS: In vitro, EEP showed an antiestrogenic activity in both HEK293T ER-α and ER-ß cells. In vivo, EEP induced a significant increase in a bell shape dose response manner of the uterine wet weight, the total protein levels in the uterus, the uterine and vaginal epithelium height and acini border cells of mammary gland with the presence of abundant eosinophil secretions. Moreover, EEP induced a significant decrease in the total number, average duration as well as frequency of hot flushes after 3 days of treatment in rat (equivalent to a month in woman). The dose of 150 mg/kg exhibited the most potent estrogenic effects among all the tested doses. The UPLC-HRMS analysis showed the presence of caffeic acid derivatives and trirtepernoids in EEP, which are well known endowed with estrogenic properties. CONCLUSION: These results suggest that Ethanolic extract of Cameroonian propolis has estrogen-like effects in vivo and may alleviate some menopausal problems such as vaginal dryness and hot flushes. Ethanol-extracted Cameroobian propolis exhibited in vitro and in vivo estrogen-like effects. This extract may contain promising phytoestrogens.

Estrogenic and cytotoxic potentials of compounds isolated from Millettia macrophylla Benth (Fabaceae): towards a better understanding of its underlying mechanisms.

BACKGROUND: Millettia macrophylla was previously reported to have estrogenic effects and to prevent postmenopausal osteoporosis in Wistar rats. So, the study deals with the identification of its secondary metabolites and the evaluation of their estrogenicity and cytotoxicity toward tumoural cells. Thus, 13 known compounds were obtained from successive chromatographic columns and identified by NMR data compared to those previously reported. METHODS: In vitro estrogenicity of the isolates and the phenolic fraction (PF) of M. macrophylla were performed by E-screen and reporter gene assays, while their cytotoxicity was evaluated by Alamar Blue (resazurin) assay. A 3-days uterotrophic assay and the ability of PF to alleviate hot flushes in ovariectomized adult rats were tested in vivo. RESULTS: Seven of the 13 secondary metabolites turned to be estrogenic. Only two exhibited cytotoxic effects on MCF-7 and MDA-MB-231 with CC50 values of 110 µM and 160 µM, respectively. PF induced a significant (p < 0.01) MCF-7 cells proliferation and transactivated both ERα and ERß in the reported gene assay at 10-2 µg/mL. In vivo, PF acted more efficiently than the methanol crude extract, resulting to a significant (p < 0.01) increase in the uterine wet weight, uterine protein level, uterine and vaginal epithelial height at the dose of 10 mg/kg BW. In addition, PF reduced the average duration and frequency of hot flushes induced in rat. CONCLUSION: These aforementioned results indicate that PF is a good candidate for the preparation of an improved traditional medicine able to alleviate some menopausal complaints such as vaginal dryness and hot flushes. Estrogenic and cytotoxic potentials of compounds isolated from Millettia macrophylla Benth. (Fabaceae): towards a better understanding of its underlying mechanism.

Estrogenic effects of Ficus umbellata Vahl. (Moraceae) extracts and their ability to alleviate some menopausal symptoms induced by ovariectomy in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Ficus umbellata Vahl. (Moraceae) is a medicinal plant used in Cameroon to treat amenorrhea as well as other physiological disorders related to menopause. AIM OF STUDY: In order to justify scientifically its traditional use, the estrogen-like properties of the aqueous (AE) and methanol (MeOH) extracts of F. umbellata were investigated. MATERIAL AND METHODS: In vitro, the ability of different extracts of F. umbellata to activate estrogen receptors α (ERα) and ß (ERß) in cell-based reporter gene assays using human embryonic kidney (HEK293T) cells transfected with ERs was tested. In vivo, a 3-day uterotrophic assay and the capacity of the extracts to alleviate hot flushes in ovariectomized adult rats were tested. Using a bioassay-guided fractionation the major compound of F. umbellata was isolated and tested in vitro on HEK293T-ERα and ERß cells. RESULTS: AE and MeOH extracts significantly altered ERα as well as ERß activities. In vivo, both extracts significantly increase the uterine and vaginal epithelium thickness, and uterine total protein levels in a dose dependent manner. Interestingly, both extracts of F. umbellata at the dose of 100 mg/kg BW significantly decreased the total number, average duration as well as frequency of hot flushes in experimental rats compared to age-matched OVX controls. Finally, 7-methylumbelliferone, a coumarin was characterized as the major compound of F. umbellata; however this compound did not transactivate ERα as well ERß in vitro. CONCLUSION: These aforementioned results suggest that F. umbellata extracts as used by the traditional practitioner have estrogen-like effects and may alleviate some menopausal problems such as vaginal dryness and hot flushes.

Flavonoids, Breast Cancer Chemopreventive and/or Chemotherapeutic Agents.

Flavonoids are secondary metabolites abundantly present in commonly consumed fruits and vegetables. They possess diverse properties such as anti-inflammatory, anti-oxidant and anti-cancer. Epidemiologic studies suggest that an enrich flavonoids diet is linked to a decreased risk of breast cancer. These protective properties are due to the alteration of numerous signalling pathways involved in cancer-related phenomena such as inflammation and proliferation. Human clinical trials examining the effect of supplementation of some flavonoids on disease prevention have been conducted. There is no natural flavonoid that has been approved for the treatment of breast cancer. However, natural flavonoids served as lead compounds in the synthesis of cancer chemopreventive and/or therapeutic agents.

Insights into Orphan Nuclear Receptors as Prognostic Markers and Novel Therapeutic Targets for Breast Cancer.

There is emerging evidence asserting the importance of orphan nuclear receptors (ONRs) in cancer initiation and progression. In breast cancer, there is a lot unknown about ONRs in terms of their expression profile and their transcriptional targets in the various stages of tumor progression. With the classification of breast tumors into distinct molecular subtypes, we assess ONR expression in the different breast cancer subtypes and with patient outcomes. Complementing this, we review evidence implicating ONR-dependent molecular pathways in breast cancer progression to identify candidate ONRs as potential prognostic markers and/or as therapeutic targets.

Flavonoids, Breast Cancer Chemopreventive and/or Chemotherapeutic Agents

Flavonoids are secondary metabolites abundantly present in commonly consumed fruits and vegetables. They possess diverse properties such as anti-inflammatory, anti-oxidant and anti-cancer. Epidemiologic studies suggest that an enrich flavonoids diet is linked to a decreased risk of breast cancer. These protective properties are due to the alteration of numerous signalling pathways involved in cancer-related phenomena such as inflammation and proliferation. Human clinical trials examining the effect of supplementation of some flavonoids on disease prevention have been conducted. There is no natural flavonoid that has been approved for the treatment of breast cancer. However, natural flavonoids served as lead compounds in the synthesis of cancer chemopreventive and/or therapeutic agents.

GEMIN4 functions as a coregulator of the mineralocorticoid receptor.

The mineralocorticoid receptor (MR) is a member of the nuclear receptor superfamily. Pathological activation of the MR causes cardiac fibrosis and heart failure, but clinical use of MR antagonists is limited by the renal side effect of hyperkalemia. Coregulator proteins are known to be critical for nuclear receptor-mediated gene expression. Identification of coregulators, which mediate MR activity in a tissue-specific manner, may allow for the development of novel tissue-selective MR modulators that confer cardiac protection without adverse renal effects. Our earlier studies identified a consensus motif among MR-interacting peptides, MPxLxxLL. Gem (nuclear organelle)-associated protein 4 (GEMIN4) is one of the proteins that contain this motif. Transient transfection experiments in HEK293 and H9c2 cells demonstrated that GEMIN4 repressed agonist-induced MR transactivation in a cell-specific manner. Furthermore, overexpression of GEMIN4 significantly decreased, while knockdown of GEMIN4 increased, the mRNA expression of specific endogenous MR target genes. A physical interaction between GEMIN4 and MR is suggested by their nuclear co-localization upon agonist treatment. These findings indicate that GEMIN4 functions as a novel coregulator of the MR.