A facile six-step synthesis (15.2% yield) of ent-17β-estradiol from readily accessible precursors is described. The preparation of analogues with 2-alkyl substitutents, double bond unsaturation in the C-ring, a cis C, D-ring fusion and modified substituents at C17 is also reported.
ent-17β-estradiol; enantiomer; neuroprotectants; antioxidants; estradiol analogues
Calcitriol (1,25-dihydroxyvitamin D3), the hormonally active form of vitamin D, inhibits the growth of many malignant cells including breast cancer (BCa) cells. The mechanisms of calcitriol anticancer actions include cell cycle arrest, stimulation of apoptosis and inhibition of invasion, metastasis and angiogenesis. In addition we have discovered new pathways of calcitriol action that are especially relevant in inhibiting the growth of estrogen receptor positive (ER+) BCa cells. Calcitriol suppresses COX-2 expression and increases that of 15-PGDH thereby reducing the levels of inflammatory prostaglandins (PGs). Our in vitro and in vivo studies show that calcitriol decreases the expression of aromatase, the enzyme that catalyzes estrogen synthesis selectively in BCa cells and in the mammary adipose tissue surrounding BCa, by a direct repression of aromatase transcription via promoter II as well as an indirect effect due to the reduction in the levels of PGs, which are major stimulator of aromatase transcription through promoter II. Calcitriol down-regulates the expression of ERα and thereby attenuates estrogen signaling in BCa cells including the proliferative stimulus provided by estrogens. Thus the inhibition of estrogen synthesis and signaling by calcitriol and its anti-inflammatory actions will play an important role in inhibiting ER+ BCa. We hypothesize that dietary vitamin D would exhibit similar anticancer activity due to the presence of the enzyme 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) in breast cells ensuring conversion of circulating 25-hydroxyvitamin D to calcitriol locally within the breast micro-environment where it can act in a paracrine manner to inhibit BCa growth. Cell culture and in vivo data in mice strongly suggest that calcitriol and dietary vitamin D would play a beneficial role in the prevention and/or treatment of ER+ BCa in women.
Calcitriol; breast cancer; anti-proliferative effects; anti-inflammatory effects; aromatase; prostaglandins; aromatase inhibitors; estrogen receptor; dietary vitamin D
Progesterone receptor membrane component 1 (PGRMC1) is highly expressed in the granulosa and luteal cells of rodent and primate ovaries. Interestingly, its molecular weight as assessed by Western blot is dependent on its cellular localization with a ≈ 27 kDa form being detected in the cytoplasm and higher molecular weight forms being detected in the nucleus. The higher molecular weight forms of PGRMC1 are sumoylated suggesting that they are involved in regulating gene transcription, since sumoylation of nuclear proteins often is associated with regulation of transcriptional activity of the sumoylated protein.
In order to identify a set of candidate genes that are regulated by PGRMC1, a human granulosa/luteal cell line (hGL5 cells) was treated with PGRMC1 siRNA and changes in gene expression monitored by microarray analysis. The microarray analysis revealed that PGRMC1 generally functioned as a repressor of transcription, since depletion of PGRMC1 resulted in a disproportionate increase in the number of transcripts. Moreover, a pathway analysis implicated PGRMC1 in the regulation of apoptosis, which is consistent with PGRMC1’s known biological action. More importantly these results support the concept that PGRMC1 influences gene transcription. Additional studies reveal that progesterone (P4) acting through a PGRMC1-dependent mechanism suppresses the activity of the transcription factor, Tcf/Lef, thereby identifying one molecular pathway through which P4-PGRMC1 can regulate gene transcription and ultimately apoptosis.
Progesterone; PGRMC1; Ovary; Gene Expression; Tcf/Lef Transcription Factor Activity; Sumoylation; Apoptosis
Hypothesizing that rapid estrogen signaling could be modulated from different estrogen receptors with unique localization patterns, a number of groups have attempted to design drug conjugates that target or restrict compounds to specific subcellular compartments. This article will briefly discuss the history of using conjugates to dissect rapid estrogen signaling and different strategies to attempt to target estrogens and antiestrogens to different locations. It will also detail some of the potential issues that can arise with different types of conjugates, using examples drawn from the authors’ own work.
Rapid Estrogen Signaling; Drug Conjugates; E2-BSA; 4-hydroxytamoxifen; membrane estrogen receptors
The role of metabolic disturbance in polycystic ovary syndrome (PCOS) has been well established, with insulin resistance and the resulting compensatory hyperinsulinemia thought to promote hyperandrogenemia. Genome-wide association studies (GWAS) have established a large number of loci for metabolic conditions such as type 2 diabetes and obesity. A subset of these loci has been investigated for a role in PCOS; these studies generally have not revealed a confirmed role for these loci in PCOS risk. However, a large scale investigation of genes related to these pathways has not previously been performed. We conducted a two stage case control association study of 121,715 single nucleotide polymorphisms (SNPs) selected to represent susceptibility loci associated with traits such as type 2 diabetes, obesity measures, lipid levels and cardiovascular function using the Cardio-Metabochip in 847 PCOS cases and 845 controls. Several hypothesis-generating associations with PCOS were observed (top SNP rs2129107, P = 3.8 × 10−6). We did not find any loci definitively associated with PCOS after strict correction for multiple testing, suggesting that cardio-metabolic loci are not major risk factors underlying the susceptibility to PCOS.
Candidate-wide association study; Polycystic ovary syndrome; Cardio-Metabochip; Single nucleotide polymorphism; Genetic association
Estrogen receptor (ER) β was discovered over a decade ago. The design of most studies on this receptor was based on knowledge of its predecessor, ERα. Although breast cancer (BCa) has been a main focus of ERβ research, its precise roles in breast carcinogenesis remain elusive. Data from in vitro models have not always matched those from observational or clinical studies. Several inherent factors may contribute to these discrepancies: a) several ERβ spliced variants are expressed at the protein level, and isoform-specific antibodies are unavailable for some variants; b) post-translational modifications of the receptor regulate receptor functions; c) the role of the receptor differs significantly depending on the type of ligands, cis-elements, and co-regulators that interact with the receptor; and d) the diversity of distribution of the receptor among intracellular organelles of BCa cells. This review addresses the gaps in knowledge in ERβ research as it pertains to BCa regarding the following questions: 1) is ERβ a tumor suppressor in BCa?; 2) do ERβ isoforms play differential roles in breast carcinogenesis?; 3) do nuclear signaling and extranuclear ERβ signaling differ in BCa?; 4) what are the consequences of post-translational modifications of ERβ in BCa?; 5) how do co-regulators and interacting proteins increase functional diversity of ERβ?; and 6) how do the types of ligand and regulatory cis-elements affect the action of ERβ in BCa? Insights gained from these key questions in ERβ research should help in prevention, diagnosis/prognosis, and treatment of BCa.
ERbeta isoforms; tumor suppressor; post- translational modification; extranuclear localization; co-regulators; phytoestrogen
Progesterone plays a central role in women’s reproductive health. Synthetic progestins, such as medroxyprogesterone acetate (MPA) are often used in hormone replacement therapy (HRT), oral contraceptives, and for the treatment of endometriosis and infertility. Although MPA is clinically effective, it also promiscuously binds to androgen and glucocorticoid receptors (AR/GR) leading to many undesirable side effects including cardiovascular diseases and breast cancers. Therefore, identifying alternative progestins is clinically significant. The purpose of this study was to biologically characterize non-steroidal progestins from botanicals by investigating their interaction and activation of progesterone receptor (PR). Eight botanicals commonly used to alleviate menopausal symptoms were investigated to determine if they contain progestins using a progesterone responsive element (PRE) luciferase reporter assay and a PR polarization competitive binding assay. Red clover extract stimulated PRE-luciferase and bound to PR. A library of purified compounds previously isolated from red clover was screened using the luciferase reporter assay. Kaempferol identified in red clover and a structurally similar flavonoid, apigenin, bound to PR and induced progestegenic activity and P4 regulated genes in breast epithelial cells and human endometrial stromal cells (HESC). Kaempferol and apigenin demonstrated higher progestegenic potency in the HESC compared to breast epithelial cells. Furthermore, phytoprogestins were able to activate P4 signaling in breast epithelial cells without downregulating PR expression. These data suggest that botanical extracts used for women’s health may contain compounds capable of activating progesterone receptor signaling.
Progesterone receptor; Red clover; Flavonoid; Kaempferol; Apigenin; Naringenin
Tamoxifen (Tam), and its active metabolite, 4-hydroxytamoxifen (OHT), compete with estrogens for binding to the estrogen receptor (ER). Tam and OHT can also induce ER-dependent apoptosis of cancer cells. 10–100 nM OHT induces ER-dependent apoptosis in ~3 days. Using HeLaER6 cells, we examined the role of OHT activation of signal transduction pathways in OHT-ER-mediated apoptosis. OHT-ER activated the p38, JNK and ERK1/2 pathways. Inhibition of p38 activation with SB203580, or RNAi-knockdown of p38α, moderately reduced OHT-ER mediated cell death. A JNK inhibitor partly reduced cell death. Surprisingly, the MEK1/2 inhibitor, PD98059, completely blocked OHT-ER induced apoptosis. EGF, an ERK1/2 activator, enhanced OHT-induced apoptosis. OHT induced a delayed and persistent phosphorylation of ERK1/2 that persisted for >80 hours. Addition of PD98059 as late as 24 hours after OHT largely blocked OHT-ER mediated apoptosis. The antagonist, ICI 182,780, blocked both the long-term OHT-mediated phosphorylation of ERK1/2 and OHT-induced apoptosis. Our data suggests that the p38 and JNK pathways, which often play a central role in apoptosis, have only a limited role in OHT-ER-mediated cell death. Although rapid activation of the ERK1/2 pathway is often associated with cell growth, persistent activation of the ERK1/2 pathway is essential for OHT-ER induced cell death.
Tamoxifen; Apoptosis; ERK; Estrogen Receptor
The progesterone receptor (PR) plays a key role in reproduction and is important in cancers of the reproductive tract. Current PR antagonists usually compete for progestin binding in the PR ligand-binding pocket and often exhibit cross-binding with other members of the steroid receptor family. Using stably transfected cells expressing reporter genes, a set of ~150 theophylline analogues were screened for their ability to inhibit progesterone, estrogen, glucocorticoid and androgen signaling. The structure-activity studies presented here identify branched 8-alkylthio-6-thio-substitutions of theophylline as selective PR inhibitors. 6-thio-8-(2-ethylbutyl)thiotheophylline (51), the most extensively studied derivative, does not act by competing with progestins for binding in the ligand-binding pocket of PR. It demonstrated the ability to inhibit the mouse mammary tumor virus (MMTV)-luciferase reporter and endogenous PR-regulated alkaline phosphatase activity in T47D breast cancer cells. Compound 51 is the lead member of a novel class of PR inhibitors that act outside the PR ligand-binding pocket, thus serving as a novel probe to investigate PR action and a lead for further development.
Progesterone receptor; Steroid receptor; Small molecule inhibitor; Theophylline analogue; Structure activity relationship
Cigarette tobacco smoke is a potent environmental contaminant known to adversely affect health including fertility and pregnancy.
To examine the associations between second-hand cigarette tobacco-smoke exposure, or active smoking and serum concentrations of steroid hormones using tandem mass spectrometry.
Healthy women (18–45 y) from the general community in the Metropolitan Washington, DC were recruited at the follicular stage of their menstrual cycle. Participants were assigned to one of three study groups: active smokers (N= 107), passive smokers (N= 86), or non-smokers (N= 100). Classifications were based on a combination of self-reporting and serum cotinine concentrations.
Serum androgens, estrogens, progestins, androstenedione, aldosterone, cortisol, corticosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), 11-deoxycortisol and 25-hydroxy-vitamin D3 (25-OHVitD3) and cotinine were measured by isotope dilution tandem mass spectrometry (LC/MS/MS) (API-5000). Kruskal–Wallis tests were used to assess median differences among the three groups, with Dunn’s multiple comparison test for post hoc analysis.
Serum estrone, estradiol, and estriol concentrations were lower in active and passive smokers than in non-smokers. The three study groups differed significantly in serum concentrations of 16-OHE1, aldosterone and 25-OHVitD3, as well as in the ratios of many of the steroids. Pair-wise comparison of the groups demonstrated significant differences in hormone concentrations between (i) smokers and nonsmokers for aldosterone: (ii) passive smokers and non-smokers for aldosterone, progesterone and estriol. Moreover, for smokers and passive smokers, there were no significant differences in these hormone concentrations.
Smoke exposure was associated with lower than normal median steroid hormone concentrations. These processes may be instrumental in explaining some adverse effects of tobacco smoke on female health and fertility.
Environmental toxicants; Cigarette tobacco smoke exposure; Mineralocorticoids; Sex hormones; Stress hormones; Tandem mass spectrometry
The vitamin D3 catabolizing enzyme, CYP24, is frequently over-expressed in tumors, where it may support proliferation by eliminating the growth suppressive effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). However, the impact of CYP24 expression in tumors or consequence of CYP24 inhibition on tumor levels of 1,25(OH)2D3
in vivo has not been studied due to the lack of a suitable quantitative method. To address this need, an LC-MS/MS assay that permits absolute quantitation of 1,25(OH)2D3 in plasma and tumor was developed. We applied this assay to the H292 lung tumor xenograft model: H292 cells eliminate 1,25(OH)2D3 by a CYP24-dependent process in vitro, and 1,25(OH)2D3 rapidly induces CYP24 expression in H292 cells in vivo. In tumor-bearing mice, plasma and tumor concentrations of 1,25(OH)2D3 reached a maximum of 21.6 ng/mL and 1.70 ng/mL respectively, following intraperitoneal dosing (20 µg/kg 1,25(OH)2D3). When co-administered with the CYP24 selective inhibitor CTA091 (250 µg/kg), 1,25(OH)2D3 plasma levels increased 1.6-fold, and tumor levels increased 2.6-fold. The tumor/plasma ratio of 1,25(OH)2D3 AUC was increased 1.7-fold by CTA091, suggesting that the inhibitor increased the tumor concentrations of 1,25(OH)2D3 independent of its effects on plasma disposition. Compartmental modeling of 1,25(OH)2D3 concentration versus time data confirmed that: 1,25(OH)2D3 was eliminated from plasma and tumor; CTA091 reduced the elimination from both compartments; and that the effect of CTA091 on tumor exposure was greater than its effect on plasma. These results provide evidence that CYP24-expressing lung tumors eliminate 1,25(OH)2D3 by a CYP24-dependent process in vivo and that CTA091 administration represents a feasible approach to increase tumor exposure to 1,25(OH)2D3.
lung cancer; CTA091; CYP24; 1,25-dihydroxyvitamin D3; pharmacokinetics
Pure antiestrogens were clinically developed as alternative therapies for estrogen receptor (ER) positive breast cancers. Unlike the selective estrogen receptor modulators (SERMs), these antiestrogens are devoid of tissue-specific ER agonist activity. Many of these compounds are steroidal in nature, containing an estradiol (E2) structural core with long alkyl side chains at the C-7α position. Two novel 7α-substituted E2 derivatives were evaluated that retain high binding affinity for ER. Compared to known pure antiestrogens, these compounds, referred to as compound 13 (C13) and C14, contain shorter 7α alkyl side chains and differ only in their terminal substituent: a hydroxyl moiety versus a benzyloxy group, respectively. Herein we assessed the effects of these compounds on ER transcriptional activity and report that despite their similar overall structure, C13 and C14 produce distinct cell type-specific responses. Of note, C13 functions as a mixed agonist/antagonist in Hela cells, inducing only weak ER transcriptional activity while preventing coactivator recruitment and stabilizing ER expression. However, this compound effectively stimulates ER activity in MCF-7 cells, does not increase ER levels and promotes cell proliferation on par with E2. Conversely, C14 stimulates transcriptional activity in both cell types and enhances ER-coactivator interactions. The activities of both compounds were inhibited by the pure antiestrogen ICI 182,780. Taken together, these results reveal that C13 is a SERM while C14 is an ER agonist, and indicate that the terminal modification of the C-7α hexanyl side chain of these estradiol derivatives is an important determinant of the biocharacter of these ER ligands.
estrogen receptor; coactivator; SERM; antiestrogen; pharmacology
Aldosterone stimulates the endothelin-1 gene (Edn1) in renal collecting duct (CD) cells by a mechanism involving the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). The goal of the present study was to determine if the synthetic glucocorticoid dexamethasone affected Edn1 gene expression and to characterize GR binding patterns to an element in the Edn1 promoter. Dexamethasone (1 μM) induced a 4-fold increase in Edn1 mRNA in mIMCD-3 inner medullary CD cells. Similar results were obtained from cortical collecting duct-derived mpkCCDc14 cells. RU486 inhibition of GR completely blocked dexamethasone action on Edn1. Similarly, 24h transfection of siRNA against GR reduced Edn1 expression by approximately 50%. However, blockade of MR with either spironolactone or siRNA had little effect on dexamethasone induction of Edn1. Cotransfection of MR and GR siRNAs together had no additive effect compared to GR-siRNA alone. The results indicate that dexamethasone acts on Edn1 exclusively through GR and not MR. DNA affinity purification studies revealed that either dexamethasone or aldosterone resulted in GR binding to the same hormone response element in the Edn1 Edn1 promoter. The Edn1 hormone response element contains three important sequence segments. Mutational analysis revealed that one of these segments is particularly important for modulating MR and GR binding to the Edn1 hormone response element.
Dexamethasone; glucocorticoid response element; endothelin-1; collecting duct; glucocorticoid receptor
Exogenous androgens can lower HDL-cholesterol (HDL-C) concentrations, yet men with low serum testosterone have elevated rates of cardiovascular disease (CVD). HDL function may better predict CVD risk than absolute HDL-C quantity. We evaluated the acute effects of medical castration in men on HDL-C, cholesterol efflux capacity and HDL protein composition. Twenty-one healthy men, ages 18–55, received the GnRH antagonist acyline and one of the following for 28 days: Group 1: placebo, Group 2: transdermal testosterone gel and placebo, Group 3: transdermal testosterone gel and an aromatase inhibitor. Sex steroids, fasting lipids, and cholesterol efflux to apoB-depleted serum were measured in all subjects. The HDL proteome was assessed in Group 1 subjects only. In Group 1, serum testosterone concentrations were reduced by >95%, and HDL-C and cholesterol efflux capacity increased (p=0.02 and p=0.04 vs. baseline, respectively). HDL-associated clusterin increased significantly with sex steroid withdrawal (p=0.007 vs. baseline). Testosterone withdrawal in young, healthy men increases HDL-C and cholesterol efflux capacity. Moreover, sex steroid deprivation changes HDL protein composition. Further investigation of the effects of sex steroids on HDL composition and function may help resolve the apparently conflicting data regarding testosterone, HDL-C, and CVD risk.
testosterone; estradiol; HDL cholesterol; cardiovascular disease; apolipoproteins; atherosclerosis
Multiple physiologic estrogens (estradiol, estriol, and estrone), as well as xenoestrogenic compounds (including alkylphenols and bisphenol A), can act via nongenomic signaling initiated by liganding of the plasma membrane estrogen receptor-α (mERα). We examined heterotrimeric G protein involvement leading to extracellular-regulated kinase (ERK) activation in GH3/B6/F10 rat anterior pituitary tumor cells that express abundant mERα, and smaller amounts of mERβ and GPR30. A combination of microarrays, immunoblots, and quantitative immunoassays demonstrated the expression of members of all α, β, and γ G protein classes in these cells. Use of selective inhibitors showed that the Gαi subtype was the primary initiator of downstream ERK signaling. Using antibodies against the GTP-bound form of Gα protein subtypes i and s, we showed that xenoestrogens (bisphenol A, nonylphenol) activated Gαi at 15-30 sec; all alkylphenols examined subsequently suppressed activation by 5 min. GTP-activation of Gαi for all estrogens was enhanced by irreversible cumulative binding to GTPγS. In contrast, Gαs was neither activated nor deactivated by these treatments with estrogens. ERα and Gαi co-localized outside nuclei and could be immuno-captured together. Interactions of ERα with Gαi and caveolin I were demonstrated by epitope proximity ligation assays. An ERα/β antagonist (ICI182780) and a selective disruptor of caveolar structures (nystatin) blocked estrogen-induced ERK activation.
Xenoestrogens, like physiologic estrogens, can evoke downstream kinase signaling involving selective interactions of ERα with Gαi and caveolin I, but with some different characteristics, which could explain their disruptive actions.
membrane estrogen receptor; GPR30; nongenomic; GH3 cells; bisphenol A; alkylphenols
As part of our program to explore the influence of small structural modifications on the biological response of the estrogen receptor-α (ERα), we prepared and evaluated a series of mono-and di-substituted phenyl vinyl estradiols. The target compounds were prepared in 45 -80 % yields using the Stille coupling reaction and evaluated using competitive binding analysis with the ERα-ligand binding domain (hERα-LBD) and estrogenic activity (induction of alkaline phosphatase in Ishikawa cells). Results indicated that the 2,4- and 2,5-dimethyl derivatives, 5b and 5c, had the highest relative binding affinity (RBA= 20.5 and 37.3%) and relative stimulatory activity (RSA = 101.0 and 12.3%) of the di-methyl series.
Steroidal estrogens; estrogen receptor; ligand binding domain; synthesis; molecular modeling; binding assay
Polycystic ovary syndrome (PCOS) affects between 5 and 8% of women, making it one of the most common endocrinopathies in women. The disorder typically has its onset at puberty with evidence of excessive androgen production, obesity, and insulin resistance. Women with PCOS are more insulin resistant than weight-matched controls and have an exceptionally high prevalence of early-onset impaired glucose tolerance (30 - 40 percent), and type 2 diabetes (up to 10 percent). Over the past several years, chronic decreases in sleep duration and/or quality have been identified as a risk for the development of a number of metabolic derangements that are strikingly similar to those seen in PCOS. Specifically, decreased sleep quality due to obstructive sleep apnea (OSA) has been causally linked to insulin resistance, glucose intolerance, dyslipidemia and hypertension independent of body mass index (BMI). Until recently, however, it had not been recognized that OSA is present in a disproportionate number of women with PCOS: the risk for OSA is at least 5-10 fold higher compared to the risk in similarly obese women without PCOS. The causes and consequences of OSA in women with PCOS are addressed in this manuscript.
Polycystic ovary syndrome; obstructive sleep apnea; metabolic syndrome; type 2 diabetes mellitus; impaired glucose tolerance; insulin resistance; obesity; cardiovascular; dyslipidemia
Chronic low-grade inflammation has emerged as a key contributor to the pathogenesis of Polycystic Ovary Syndrome (PCOS). A dietary trigger such as glucose is capable of inciting oxidative stress and an inflammatory response from mononuclear cells (MNC) of women with PCOS, and this phenomenon is independent of obesity. This is important because MNC-derived macrophages are the primary source of cytokine production in excess adipose tissue, and also promote adipocyte cytokine production in a paracrine fashion.
The proinflammatory cytokine tumor necrosis factor-α (TNFα) is a known mediator of insulin resistance. Glucose-stimulated TNFα release from MNC along with molecular markers of inflammation are associated with insulin resistance in PCOS. Hyperandrogenism is capable of activating MNC in the fasting state, thereby increasing MNC sensitivity to glucose; and this may be a potential mechanism for promoting diet-induced inflammation in PCOS.
Increased abdominal adiposity is prevalent across all weight classes in PCOS, and this inflamed adipose tissue contributes to the inflammatory load in the disorder. Nevertheless, glucose ingestion incites oxidative stress in normal weight women with PCOS even in the absence of increased abdominal adiposity.
In PCOS, markers of oxidative stress and inflammation are highly correlated with circulating androgens. Chronic suppression of ovarian androgen production does not ameliorate inflammation in normal weight women with the disorder. Furthermore, in vitro studies have demonstrated the ability of pro-inflammatory stimuli to upregulate the ovarian theca cell steroidogenic enzyme responsible for androgen production. These findings support the contention that inflammation directly stimulates the polycystic ovary to produce androgens.
Hyperandrogenism; inflammation; oxidative stress; insulin resistance; ovarian dysfunction; abdominal adiposity
Polycystic ovary syndrome (PCOS) is associated with metabolic derangements including insulin resistance, dyslipidemia, systemic inflammation and endothelial dysfunction. There is a growing need to develop pharmacologic interventions to improve metabolic function in women with PCOS. Medications that have been tested in patients with PCOS include metformin, thiazolidinediones, acarbose, naltrexone, orlistat, vitamin D and statins.
Metformin decreases hepatic gluconeogenesis and free fatty acid oxidation while increasing peripheral glucose uptake. Early studies in PCOS suggested that metformin indirectly reduces insulin level, dyslipidemia and systemic inflammation; however, recent placebo-controlled trials failed to demonstrate significant metabolic benefit. Thiazolidinediones act primarily by increasing peripheral glucose uptake. Most studies in PCOS have demonstrated that thiazolidinediones reduce insulin resistance; however, effects on dyslipidemia were disappointing. Use of thiazolidinediones is associated with weight gain and major complications. Acarbose reduces digestion of polysaccharides. Studies in PCOS yielded inconsistent effects of acarbose on insulin sensitivity and no significant improvement of dyslipidemia. Naltrexone reduces appetite and modulates insulin release; its use in PCOS may reduce hyperinsulinemia. Orlistat decreases absorption of dietary fats; studies in PCOS suggest beneficial effects on insulin sensitivity. Vitamin D may improve insulin sensitivity but mixed results on lipid profile in PCOS have been reported. Statins are competitive inhibitors of the key enzyme regulating the mevalonate pathway; their effects are related to reduced cholesterol production as well as anti-inflammatory and anti-oxidant properties. In women with PCOS, statins reduce hyperandrogenism, improve lipid profile and reduce systemic inflammation while the effects on insulin sensitivity are variable. Use of statins is contraindicated in pregnancy.
Polycystic ovary syndrome; Metabolic dysfunction; Insulin sensitivity; Dyslipidemia; Inflammation
Polycystic ovarian syndrome (PCOS) is a common disorder characterized by ovulatory dysfunction and hyperandrogenemia (HA). Neuroendocrine abnormalities including increased gonadotropin-releasing hormone (GnRH) pulse frequency, increased luteinizing hormone (LH) pulsatility, and relatively decreased follicle stimulating hormone contribute to its pathogenesis. HA reduces inhibition of GnRH pulse frequency by progesterone, causing rapid LH pulse secretion and increasing ovarian androgen production. The origins of persistently rapid GnRH secretion are unknown but appear to evolve during puberty. Obese girls are at risk for HA and develop increased LH pulse frequency with elevated mean LH by late puberty. However, even early pubertal girls with HA have increased LH pulsatility and enhanced daytime LH pulse secretion, indicating the abnormalities may begin early in puberty. Decreasing sensitivity to progesterone may regulate normal maturation of LH secretion, potentially related to normally increasing levels of testosterone during puberty. This change in sensitivity may become exaggerated in girls with HA. Many girls with HA—especially those with hyperinsulinemia—do not exhibit normal LH pulse sensitivity to progesterone inhibition. Thus, HA may adversely affect LH pulse regulation during pubertal maturation leading to persistent HA and the development of PCOS.
Polycystic ovarian syndrome; Gonadotropin releasing hormone; Obesity; Puberty; Hyperandrogenemia; Neuroendocrine
Selective inhibitors of CYP24A1 represent an important synthetic target in a search for novel vitamin D compounds of therapeutic value. In the present work, we show the synthesis and biological properties of two novel side chain modified 2-methylene-19-nor-1,25(OH)2D3 analogs, the 22-imidazole-1-yl derivative 2 (VIMI) and the 25-N-cyclopropylamine compound 3 (CPA1), which were efficiently prepared in convergent syntheses utilizing the Lythgoe type Horner–Wittig olefination reaction. When tested in a cell-free assay, both compounds were found to be potent competitive inhibitors of CYP24A1, with the cyclopropylamine analog 3 exhibiting an 80–1 selective inhibition of CYP24A1 over CYP27B1. Addition of 3 to a mouse osteoblast culture sustained the level of 1,25(OH)2D3, further demonstrating its effectiveness in CYP24A1 inhibition. Importantly, the in vitro effects on human promyeloid leukemia (HL-60) cell differentiation by 3 were nearly identical to those of 1,25(OH)2D3 and in vivo the compound showed low calcemic activity. Finally, the results of preliminary theoretical studies provide useful insights to rationalize the ability of analog 3 to selectively inhibit the cytochrome P450 isoform CYP24A1.
1; 25-Dihydroxyvitamin D3; Cytochrome P450 inhibitors; CYP24A1; Cyclopropylamines; Cancer therapy; Molecular docking
Although exogenous glucocorticoids (GC) play a role in the regulation of bone marrow mesenchymal stem/stromal cells (MSCs) proliferation and differentiation, the function of endogenous GC is not well understood. The purpose of this study was to investigate the effect of the blockage of endogenous GC using RU486, an antagonist of the glucocorticoid receptor, on the in vitro proliferation and differentiation capabilities of human MSCs. We quantitatively measured cell proliferation of human MSCs after treatment with increasing concentrations of RU486. We also evaluated multiple MSC differentiation capabilities, as well as the expression of stemness and senescence genes after proliferation of these human cells in vitro in the presence of RU486 at 10−8M. It was observed that RU486 treatment significantly increases the proliferation of human MSCs, although the optimal dose of RU486 for this increase in proliferation differs depending on the gender of the MSC donor. This improvement in MSC proliferation with RU486 treatment was higher in MSCs from male donors than that from females. No effect of RU486 on MSC proliferation was observed in a steroid-free medium. RU486 pretreatment significantly increased the expression of mRNA for alkaline phosphatase in human MSCs and the mRNA expression of osteocalcin of these cells up-regulated earlier after their exposure to osteogenic differentiation medium. Although no statistical significance in terms of chondrogenic differentiation markers was detected, mRNA expression for aggrecan and collagen type 2 were higher in a majority of the RU486-pretreated donor MSCs than their untreated controls. No significant difference in terms of MSC adipogenic differentiation capabilities were observed after RU486 treatment. RU486 treatment up-regulated the expressions of FGF-2 and Sox-11 in human MSCs. These results indicate that blockage of endogenous GCs may be developed as a novel approach to effectively improve the proliferation and osteochondral differentiation capabilities of human MSCs for potential clinical applications. Additional studies will be required to determine the potential long-term effects of RU486 treatment on these bone marrow cells.
Glucocorticoids; Antagonist; Bone marrow mesenchymal stem/stromal cells; Proliferation; Differentiation; Senescence
Aromatase is expressed in multiple tissues, indicating a crucial role for locally produced oestrogens in the differentiation, regulation and normal function of several organs and processes. This review is an overview of the role of aromatase in different tissues under normal physiological conditions and its contribution to the development of some oestrogen-related pathologies.
Aromatase; Oestrogen function