Estrogen-independent activation of estrogen receptors

Regular Use of Aspirin and Statins Reduces the Risk of Cancer in Individuals with Systemic Inflammatory Diseases

Aspirin has shown potential for cancer prevention, but a recent large randomized controlled trial found no evidence for a reduction in cancer risk. Given the anti-inflammatory effects of aspirin, systemic inflammatory diseases (SID), such as osteoporosis, cardiovascular diseases, and metabolic diseases, could potentially modify the aspirin-cancer link. To investigate the impact of aspirin in people with SIDs, we conducted an observational study on a prospective cohort of 478,615 UK Biobank participants. Individuals with at least one of the 41 SIDs displayed a higher cancer risk than those without SIDs. Regular aspirin use showed protective effects exclusively in patients with SID, contrasting an elevated risk among their non-SID counterparts. Nonetheless, aspirin use demonstrated preventative potential only for 9 of 21 SID-associated cancer subtypes. Cholesterol emerged as another key mediator linking SIDs to cancer risk. Notably, regular statin use displayed protective properties in patients with SID but not in their non-SID counterparts. Concurrent use of aspirin and statins exhibited a stronger protective association in patients with SID, covering 14 common cancer subtypes. In summary, patients with SIDs may represent a population particularly responsive to regular aspirin and statin use. Promoting either combined or individual use of these medications within the context of SIDs could offer a promising chemoprevention strategy.

SIGNIFICANCE

Individuals with systemic inflammatory diseases derive chemoprotective benefits from aspirin and statins, providing a precision cancer prevention approach to address the personal and public challenges posed by cancer.

Sex and sex steroids as determinants of cardiovascular risk

There are considerable sex differences regarding the risk of cardiovascular disease (CVD), including arterial hypertension, coronary artery disease (CAD) and stroke, as well as chronic renal disease. Women are largely protected from these conditions prior to menopause, and the risk increases following cessation of endogenous estrogen production or after surgical menopause. Cardiovascular diseases in women generally begin to occur at a later age than in men (on average with a delay of 10 years). Cessation of estrogen production also impacts metabolism, increasing the risk of developing obesity and diabetes. In middle-aged individuals, hypertension develops earlier and faster in women than in men, and smoking increases cardiovascular risk to a greater degree in women than it does in men. It is not only estrogen that affects female cardiovascular health and plays a protective role until menopause: other sex hormones such as progesterone and androgen hormones generate a complex balance that differentiates heart and blood vessel function in women compared to men. Estrogens improve vasodilation of epicardial coronary arteries and the coronary microvasculature by augmenting the release of vasodilating factors such as nitric oxide and prostacyclin, which are mechanisms of coronary vasodilatation that are more pronounced in women compared to men. Estrogens are also powerful inhibitors of inflammation, which in part explains their protective effects on CVD and chronic renal disease. Emerging evidence suggests that sex chromosomes also play a significant role in shaping cardiovascular risk. The cardiovascular protection conferred by endogenous estrogens may be extended by hormone therapy, especially using bioidentical hormones and starting treatment early after menopause.

Sex-dependent vascular effects of cadmium sub-chronic exposure on rats

Cadmium exposure is related to several cardiovascular diseases, such as hypertension, atherosclerosis and endothelial dysfunction. However, the toxic effect of cadmium can be dependent on the sex when examined sex in experimental models. The aim of this study was to analyze the effects of cadmium exposure on the cardiovascular system of male and female rodents. The experiments were carried out on both-sexes Wistar at 4 months of age, where from 3 months onwards, cadmium (CdCl2 100 mg/l in placed the drinking water for 30 days) or vehicle delivered (distilled water) was ingested. Before and after 30 days of exposure to cadmium, systolic blood pressure was regularly measured. After exposure, blood was collected to measure dosage of cadmium, in male and female, and estrogen in females. Vascular reactivity to phenylephrine (Phe), acetylcholine (ACh), and sodium nitroprusside (SNP) was studied at respective isolated aortic segments. After the period to Cd-exposure, systolic blood pressure was increased only in the male rats. Males also had higher levels of plasma cadmium than those of female rats, and exposure to the metal did not affect the amount of estrogen produced in the female rats. Increased myeloperoxidase (MPO) activity was also observed in both the males and females that had been exposed to the metal. Moreover, exposure to the cadmium reduced the ACh relaxation and increased vascular reactivity to Phe, resulting in an imbalance between nitric oxide superoxide anion in the isolated aorta of male rats. In female rats, sub-chronic cadmium exposure did not modify the vascular reactivity to Phe and neither to the ACh. The present study revealed that the Cd exposure for 30 days induced sex-dependent cardiovascular abnormalities.

Nox1 downregulators: A new class of therapeutics

Chronic non-communicable diseases share the pathomechanism of increased reactive oxygen species (ROS) production by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, known as Nox. The recent discovery that expression of Nox1, a Nox isoform that has been implicated in the pathogenesis of cardiovascular and kidney disease and cancer is regulated by the expression and activity of G protein-coupled estrogen receptor (GPER) led to the identification of orally active small-molecule GPER blockers as selective Nox1 downregulators (NDRs). Preclinical studies using NDRs have demonstrated beneficial effects in vascular disease, hypertension, and glomerular renal injury. These findings suggest the therapeutic potential of NDRs, which reduce Nox1 protein levels, not only for cardiovascular disease conditions including arterial hypertension, pulmonary hypertension, heart failure with preserved ejection fraction (HFpEF), and chronic renal disease, but also for other non-communicable diseases, such as cerebrovascular disease and vascular dementia, Alzheimer's disease, autoimmune diseases and cancer, in which elevated Nox1-derived ROS production plays a causal role.

GPER blockers as Nox downregulators: A new drug class to target chronic non-communicable diseases

Oxidative stress is a hallmark of chronic non-communicable diseases such as arterial hypertension, coronary artery disease, diabetes, and chronic renal disease. Cardiovascular diseases are characterized by increased production of reactive oxygen species (ROS) by NAPDH oxidase 1 (Nox1) and additional Nox isoforms among other sources. Activation of the G protein-coupled estrogen receptor (GPER) can mediate multiple salutary effects on the cardiovascular system. However, GPER also has constitutive activity, e.g. in the absence of specific agonists, that was recently shown to promote hypertension and aging-induced tissue damage by promoting Nox1-derived production of ROS. Furthermore, the small molecule GPER blocker (GRB) G36 reduces blood pressure and vascular ROS production by selectively down-regulating Nox1 expression. These unexpected findings revealed GRBs as first in class Nox downregulators capable to selectively reduce the increased expression and activity of Nox1 in disease conditions. Here, we will discuss the paradigm shift from selective GPER activation to ligand-independent, constitutive GPER signaling as a key regulator of Nox-derived oxidative stress, and the surprising identification of GRBs as the first Nox downregulators for the treatment of chronic non-communicable diseases.

Twenty years of the G protein-coupled estrogen receptor GPER: Historical and personal perspectives

Estrogens play a critical role in many aspects of physiology, particularly female reproductive function, but also in pathophysiology, and are associated with protection from numerous diseases in premenopausal women. Steroids and the effects of estrogen have been known for ∼90 years, with the first evidence for a receptor for estrogen presented ∼50 years ago. The original ancestral steroid receptor, extending back into evolution more than 500 million years, was likely an estrogen receptor, whereas G protein-coupled receptors (GPCRs) trace their origins back into history more than one billion years. The classical estrogen receptors (ERα and ERβ) are ligand-activated transcription factors that confer estrogen sensitivity upon many genes. It was soon apparent that these, or novel receptors may also be responsible for the "rapid"/"non-genomic" membrane-associated effects of estrogen. The identification of an orphan GPCR (GPR30, published in 1996) opened a new field of research with the description in 2000 that GPR30 expression is required for rapid estrogen signaling. In 2005-2006, the field was greatly stimulated by two studies that described the binding of estrogen to GPR30-expressing cell membranes, followed by the identification of a GPR30-selective agonist (that lacked binding and activity towards ERα and ERβ). Renamed GPER (G protein-coupled estrogen receptor) by IUPHAR in 2007, the total number of articles in PubMed related to this receptor recently surpassed 1000. In this article, the authors present personal perspectives on how they became involved in the discovery and/or advancement of GPER research. These areas include non-genomic effects on vascular tone, receptor cloning, molecular and cellular biology, signal transduction mechanisms and pharmacology of GPER, highlighting the roles of GPER and GPER-selective compounds in diseases such as obesity, diabetes, and cancer and the obligatory role of GPER in propagating cardiovascular aging, arterial hypertension and heart failure through the stimulation of Nox expression.

Nicolaus Copernicus and the rapid vascular responses to aldosterone

For decades, rapid steroid responses initiated by membrane receptors have been a primary research focus. G protein-coupled estrogen receptor (GPER) is activated by 17β-estradiol and participates in functional crosstalk with other steroid receptors. With reference to the physician and astronomer Nicolaus Copernicus (1473-1543), who used rigorous scientific approaches to shift paradigms and change dogma, we discuss whether GPER can also be considered an aldosterone receptor.

Sex hormones in the cardiovascular system

Gender-associated differences in the development of cardiovascular diseases have been described in humans and animals. These differences could explain the low incidence of cardiovascular disease in women in the reproductive period, such as stroke, hypertension, and atherosclerosis. The cardiovascular protection observed in females has been attributed to the beneficial effects of estrogen on endothelial function. Besides estrogen, sex hormones are able to modulate blood pressure by acting on important systems as cardiovascular, renal, and neural. They can have complementary or antagonistic actions. For example, testosterone can raise blood pressure by stimulating the renin-angiotensin-aldosterone system, whereas estrogen alone or combined with progesterone has been associated with decreased blood pressure. The effects of testosterone in the development of cardiovascular disease are contradictory. Although some researchers suggest a positive effect, others indicate negative actions of testosterone. Estrogens physiologically stimulate the release of endothelium-derived vasodilator factors and inhibit the renin-angiotensin system. Although the cardioprotective effects of estrogen are widely appreciated, little is known about the effects of progesterone, which is commonly used in hormone replacement therapy. Progesterone has both vasodilatory and vasoconstrictive effects in the vasculature, depending on the location of the vessel and the level of exposure. Nevertheless, the mechanisms through which sex hormones modulate blood pressure have not been fully elucidated. Therefore, the characterization of those could lead to a better understanding of hypertension in women and men and perhaps to improved forms of therapy.

Membrane estrogen receptor alpha is an important modulator of bone marrow C-Kit+ cells mediated cardiac repair after myocardial infarction

It has been validated that c-kit positive (c-kit+) cells in infarcted myocardium are from bone marrow (BM). Given the recent study that in the heart, estrogen receptor alpha (ERα) is involved in adaptive mechanisms by supporting cardiomyocytes survival via post-infarct cardiac c-kit+ cells, we tested a novel hypothesis that membrane ERα (mERа) supports survival of BM c-kit+ cells and enhance protective paracrine function for cardiac repair. Our data showed that myocardial infarction (MI) leads to an increase in c-kit+ first in bone marrow and then specifically within the infarcted myocardium. Also up-regulated mERа in post-infarct BM c-kit+ cells was found in day 3 post MI. In vitro co-culture system, mERа+ enhances the beneficial effects of BM c-kit+ cells by increasing their viability and reducing apoptosis. Post-infarct c-kit+ mERа+ cells population expresses predominant ERα and holds self-renewal as well as cardiac differentiation potentials after MI. In vivo, BM c-kit+ cells reduced infarct size, fibrosis and improved cardiac function. In conclusion, BM c-kit+ mERа+ exerted significantly cardiac protection after MI. A potential important implication of this study is that the manipulation of BM c-kit+ stem cells with ERа-dependent fashion may be helpful in recovering functional performance after cardiac tissue injury.

Estrogen and glucocorticoid receptor agonists and antagonists in oocytes modulate the pattern of expression of genes that encode nuclear receptor proteins in very early stage rainbow trout (Oncorhynchus mykiss) embryos

Previous studies show that changes in estrogen (ER) and glucocorticoid receptor (GR) function in rainbow trout (Oncorhynchus mykiss) oocytes modulate the growth performance phenotype of embryo and juvenile progeny; the present study was undertaken to determine whether this altered growth performance is associated with changes in the expression of several growth-related genes in early-stage embryos. Unfertilized oocytes were incubated in the presence of various combinations of GR and ER agonists and antagonists; the oocytes were then fertilized and the expression of genes that encode for six nuclear receptor superfamily (NRS) proteins (GR1, GR2, ERα, ERβ, TRα, and TRβ) and the two IGF peptides (IGF1 and IGF2) were measured in the 7-, 13-, and 26-dpf embryos. By day 26 of embryogenesis, the expression of the six NRS-related genes of interest and that of igf2 were significantly enhanced in embryos reared from ER agonist- or ER antagonist-treated oocytes, regardless of whether the GR agonist, cortisol, was also included in the initial oocyte incubation medium. Conversely, the igf1 expression pattern among treatment groups was significantly enhanced in the cortisol-only treatment group and in the ER antagonist and GR antagonist groups that were co-incubated with cortisol. Additionally, in the ER agonist treatment groups igf1 expression was significantly inhibited when cortisol was included in the oocyte incubation medium. The findings show that a single in ovo exposure to the receptor agonists/antagonists markedly changed the programming of the expression of NRS-related and IGF-related genes of the early-stage trout embryos.

GPER/GPR30 and Regulation of Vascular Tone and Blood Pressure

Natural estrogens such as 17β-estradiol are endogenous vasodilators and have been implicated in the gender differences of hypertension. These hormones activate estrogen receptors ERα and ERβ, which mediate part of estrogen-dependent vasodilation. In addition, a novel G protein-coupled estrogen-binding receptor termed GPER/GPR30 has been identified that is expressed in the cardiovascular system. Using knock-out animals or drugs selectively targeting GPER/GPR30, a significant role for this receptor as a mediator of acute estrogen-dependent vasodilation involving nitric oxide (NO) and blood pressure-lowering activity has been demonstrated. The accumulating evidence that GPER/GPR30 is responsible for control of vascular tone indicates that this receptor may represent a novel drug target for pharmacologic treatment of hypertension in postmenopausal women and possibly also men.