Theo Pelzer

Increased Mortality and Aggravation of Heart Failure in Estrogen Receptor-β Knockout Mice After Myocardial Infarction

Background—Lower mortality rates among women with chronic heart failure than among men may depend in part on the action of female sex hormones, especially estrogens. The biological effects of estrogens are mediated by 2 distinct estrogen receptor (ER) subtypes (ER&agr; and ER&bgr;). The present study was undertaken to determine the role of ER&bgr; in the development of chronic heart failure after experimental myocardial infarction (MI). Methods and Results—Female ER&bgr; null mice (BERKOChapel Hill) and wild-type littermates (WT) were ovariectomized, given 17&bgr;-estradiol, and subjected to chronic anterior MI (MI; BERKO n=31, WT n=30) or sham operation (sham; BERKO n=14, WT n=14). At 8 weeks after MI, both genotypes revealed left ventricular remodeling and impaired contractile function at similar average infarct size (BERKO-MI 32.9±5% versus WT-MI 33.0±4%); however, BERKO mice showed increased mortality (BERKO-MI 42% versus WT-MI 23%), increased body weight and fluid retention (P<0.01), higher ventricular pro-ANP expression (BERKO-MI 27.9-fold versus sham, WT-MI 5.2-fold versus sham; BERKO-MI versus WT-MI P<0.001), higher atrial natriuretic peptide serum levels, and increased phospholamban expression (P<0.05) compared with WT mice. Conclusions—Systemic deletion of ER&bgr; in female mice increases mortality, aggravates clinical and biochemical markers of heart failure, and contributes to impaired expression of Ca2+-handling proteins in chronic heart failure after MI. Further studies are required to delineate the relative importance of cardiac and vascular effects of ER&bgr; and the role of ER&agr; in the development of heart failure.

Efficacy of the Irreversible ErbB Family Blocker Afatinib in Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitor (TKI)–Pretreated Non–Small-Cell Lung Cancer Patients with Brain Metastases or Leptomeningeal Disease

Introduction: Afatinib is an effective first-line treatment in patients with epidermal growth factor receptor (EGFR)-mutated non–small-cell lung cancer (NSCLC) and has shown activity in patients progressing on EGFR-tyrosine kinase inhibitors (TKIs). First-line afatinib is also effective in patients with central nervous system (CNS) metastasis. Here we report on outcomes of pretreated NSCLC patients with CNS metastasis who received afatinib within a compassionate use program. Methods: Patients with NSCLC progressing after at least one line of chemotherapy and one line of EGFR-TKI treatment received afatinib. Medical history, patient demographics, EGFR mutational status, and adverse events including tumor progression were documented. Results: From 2010 to 2013, 573 patients were enrolled and 541 treated with afatinib. One hundred patients (66% female; median age, 60 years) had brain metastases and/or leptomeningeal disease with 74% having documented EGFR mutation. Median time to treatment failure for patients with CNS metastasis was 3.6 months, and did not differ from a matched group of 100 patients without CNS metastasis. Thirty-five percent (11 of 31) of evaluable patients had a cerebral response, five (16%) responded exclusively in brain. Response duration (range) was 120 (21–395) days. Sixty-six percent (21 of 32) of patients had cerebral disease control on afatinib. Data from one patient with an impressive response showed an afatinib concentration in the cerebrospinal fluid of nearly 1 nMol. Conclusion: Afatinib appears to penetrate into the CNS with concentrations high enough to have clinical effect on CNS metastases. Afatinib may therefore be an effective treatment for heavily pretreated patients with EGFR-mutated or EGFR–TKI-sensitive NSCLC and CNS metastasis.

Improvement of Endothelial Dysfunction by Selective Estrogen Receptor-α Stimulation in Ovariectomized SHR

Abstract—Both known estrogen receptors, ER&agr; and ER&bgr;, are expressed in blood vessels. To gain further insight into the role of ER&agr; in a functional setting, we investigated the effect of the novel highly selective ER&agr; agonist Cpd1471 on vascular reactivity in ovariectomized spontaneously hypertensive rats (SHR). After ovariectomy or sham operation, 12-week-old female SHR received either 17&bgr;-estradiol (E2, 2 &mgr;g/kg body wt per day), the selective ER&agr; agonist Cpd1471 (30 &mgr;g/kg body wt per day), or placebo. Acetylcholine-induced endothelium-dependent vasorelaxation was significantly blunted in aortas from ovariectomized rats (Rmax, 53%±3% versus sham, 79%±2%; P <0.001). Treatment with E2 or Cpd1471 significantly augmented acetylcholine-induced relaxation in ovariectomized rats (Rmax, 70%±2%; resp, 73%±2%). Endothelium-independent relaxation induced by sodium nitroprusside was not different among the four groups. The contractile response induced by the nitric oxide (NO) synthase inhibitor N&ohgr;-nitro-l-arginine, an index of basal NO formation, was significantly lower in ovariectomized rats compared with sham-operated animals (53±2% versus 77%±5%; P <0.01) and was normalized by both E2 (70%±2%) and Cpd1471 (70%±3%). Aortic endothelial NO synthase (eNOS) expression and phosphorylation of the vasodilator-stimulated phosphoprotein, an index of NO/cGMP-signaling, was reduced in ovariectomized SHR and normalized by E2 and Cpd1471. In SHR after ovariectomy, endothelium-dependent NO-mediated vasorelaxation and eNOS expression are attenuated. The novel selective ER&agr; agonist Cpd1471 prevented these pathophysiological changes to a similar extent as E2. Thus, the pharmacological principle of selective ER&agr; activation mediates positive vascular effects.

Both Estrogen Receptor Subtypes, α and β, Attenuate Cardiovascular Remodeling in Aldosterone Salt–Treated Rats

Experimental and population-based studies indicate that female gender and estrogens protect the cardiovascular system against aldosterone-induced injury. Understanding the function of estrogens in heart disease requires more precise information on the role of both estrogen receptor (ER) subtypes, ER&agr; and ER&bgr;. Therefore, we determined whether selective activation of ER&agr; or of ER&bgr; would confer redundant, specific, or opposing effects on cardiovascular remodeling in aldosterone salt–treated rats. The ER&agr; agonist 16&agr;-LE2, the ER&bgr; agonist 8&bgr;-VE2, and the nonselective estrogen receptor agonist 17&bgr;-estradiol lowered elevated blood pressure, cardiac mass, and cardiac myocyte cross-sectional areas, as well as increased perivascular collagen accumulation and vascular osteopontin expression in ovariectomized rats receiving chronic aldosterone infusion plus a high-salt diet for 8 weeks. Uterus atrophy was prevented by 16&agr;-LE2 and 17&bgr;-estradiol but not by 8&bgr;-VE2. Cardiac proteome analyses by 2D gel electrophoresis, mass spectrometry, and peptide sequencing identified specific subsets of proteins involved in cardiac contractility, energy metabolism, cellular stress response and extracellular matrix formation that were regulated in opposite directions by aldosterone salt treatment and by different estrogen receptor agonists. We conclude that activation of either ER&agr; or ER&bgr; protects the cardiovascular system against the detrimental effects of aldosterone salt treatment and confers redundant, as well as specific, effects on cardiac protein expression. Nonfeminizing ER&bgr; agonists such as 8&bgr;-VE2 have a therapeutic potential in the treatment of hypertensive heart disease.

Aging Reduces the Efficacy of Estrogen Substitution to Attenuate Cardiac Hypertrophy in Female Spontaneously Hypertensive Rats

Clinical trials failed to show a beneficial effect of postmenopausal hormone replacement therapy, whereas experimental studies in young animals reported a protective function of estrogen replacement in cardiovascular disease. Because these diverging results could in part be explained by aging effects, we compared the efficacy of estrogen substitution to modulate cardiac hypertrophy and cardiac gene expression among young (age 3 months) and senescent (age 24 months) spontaneously hypertensive rats (SHRs), which were sham operated or ovariectomized and injected with placebo or identical doses of 17&bgr;-estradiol (E2; 2 &mgr;g/kg body weight per day) for 6 weeks (n=10/group). Blood pressure was comparable among sham-operated senescent and young SHRs and not altered by ovariectomy or E2 treatment among young or among senescent rats. Estrogen substitution inhibited uterus atrophy and gain of body weight in young and senescent ovariectomized SHRs, but cardiac hypertrophy was attenuated only in young rats. Cardiac estrogen receptor-&agr; expression was lower in intact and in ovariectomized senescent compared with young SHRs and increased with estradiol substitution in aged rats. Plasma estradiol and estrone levels were lower not only in sham-operated but surprisingly also in E2-substituted senescent SHRs and associated with a reduction of hepatic 17&bgr;-hydroxysteroid dehydrogenase type 1 enzyme activity, which converts weak (ie, estrone) into potent estrogens, such as E2. Aging attenuates the antihypertrophic effect of estradiol in female SHRs and is associated with profound alterations in cardiac estrogen receptor-&agr; expression and estradiol metabolism. These observations contribute to explain the lower efficiency of estrogen substitution in senescent SHRs.

Genetic and pharmacologic strategies to determine the function of estrogen receptor α and estrogen receptor β in cardiovascular system

BACKGROUND The biological functions of estrogens extend beyond the female and male reproductive tract, affecting the cardiovascular and renal systems. Traditional views on the role of postmenopausal hormone therapy (HT) in protecting against heart disease, which were challenged by clinical end point studies that found adverse effects of combined HT, are now being replaced by more differentiated concepts suggesting a beneficial role of early and unopposed HT that does not include a progestin. OBJECTIVE We reviewed recent insights, concepts, and research results on the biology of both estrogen receptor (ER) subtypes, ERalpha and ERbeta, in cardiac and vascular tissues. Knowledge of these ER subtypes is crucial to understanding gender and estrogen effects and to developing novel, exciting strategies that may have a profound clinical impact. METHODS This review focuses on in vivo studies and includes data presented at the August 2007 meeting of the American Physiological Society as well as data from a search of the MEDLINE and Ovid databases from January 1986 to November 2007. Search results were restricted to English-language publications, using the following search terms: estrogen, estrogen receptor alpha, estrogen receptor beta, estrogen receptor alpha agonist, estrogen receptor alpha antagonist, estrogen receptor beta agonist, estrogen receptor beta antagonist, PPT, DPN, heart, vasculature, ERKO mice, BERKO mice, transgenic mice, and knockout mice. RESULTS Genetic mouse models and pharmacologic studies that employed selective as well as nonselective ER agonists support the concept that both ER subtypes confer protective effects in experimental models of human heart disease, including hypertension, cardiac hypertrophy, and chronic heart failure. CONCLUSIONS Genetic models and novel ligands hold the promise of further improving our understanding of estrogen action in multiple tissues and organs. These efforts will ultimately enhance the safety and efficacy of HT and may also result in new applications for synthetic female sex hormone analogues.

Modulation of Cardiac Hypertrophy by Estrogens

Gender-specific differences in heart disease have long been known but it has only been since the advent of molecular biology that it has become possible to investigate the molecular mechanisms. Most biochemical work in the last 50 years has focused on the characterization of the steroid hormones involved in gender specificity. More recently, the cloning of the steroid receptors and characterization of the signaling pathways through these proteins has given new insights into the mechanisms underlying the mode of action of steroid hormones. It has also become clear that the steroid receptors can be classified into families (receptors for thyroid hormone, glucocorticoids, estrogens, androgens, retinoic acid, and so called orphan receptors of mostly unknown function). The structures of these receptors show very close resemblance and all are DNA-binding proteins acting as transcription factors. Some (if not all) act as repressors of transcription of some genes in the native state and are converted to activators (or perhaps repressors of other genes) upon binding of the cognate hormone. Naturally, classical target tissues for estrogens and androgens have been studied first and only in very recent years has it been recognized that estrogens and androgens act on a much wider spectrum of tissues. In the cardiovascular field, the beneficial effect of estrogen replacement therapy in postmenopausal women which reduces the incidence of cardiovascular disease by some 40% and the lower incidence of cardiovascular disease in premenopausal women have mostly been explained by the beneficial action of estrogens on the lipid profile (increase in HDL and decrease in LDL cholesterol). Recently, functional estrogen receptors have also been shown in vascular smooth muscle cells and in the endothelium. Our own group has characterized the presence of estrogen receptors in the myocardium and in cardiac fibroblasts. We have also shown that these receptors are transcriptionally active because they are able to drive a minigene composed of a triple estrogen responsive DNA regulatory element (promoter) coupled to the firefly luciferase gene which serves as a reporter by way of its ability to drive a light-emitting reaction. We are in the process of characterizing the target genes for estrogen in the myocardium. A specific series of immediate-early genes is induced by estradiol (the major premenopausal estrogen) and we have also characterized a number of tissue-specific genes whose expression is driven by estrogens in the myocardium. The ultimate goal of these investigations is to explore the use of estrogens in the treatment of cardiac hypertrophy (and failure) by way of their properties to counteract (at least some of) the pathological switches in gene expression in these disease entities.

[ 68 Ga]Pentixafor-PET/CT for imaging of chemokine receptor 4 expression in small cell lung cancer - initial experience

Chemokine receptor CXCR4 is a key factor for tumor growth and metastasis in several types of human cancer. This study investigated the feasibility of CXCR4-directed imaging of small cell lung cancer (SCLC) with positron emission tomography/computed tomography (PET/CT) using the radiolabelled chemokine ligand [68Ga]Pentixafor. 10 patients with primarily diagnosed (n=3) or pre-treated (n=7) SCLC (n=9) or large cell neuroendocrine carcinoma of the lung (LCNEC, n=1) underwent [68Ga]Pentixafor-PET/CT. 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG, n=6) and/or somatostatin receptor (SSTR)-directed PET/CT with [68Ga]DOTATOC (n=5) and immunohistochemistry (n=10) served as standards of reference. CXCR4-PET was positive in 8/10 patients and revealed more lesions with significantly higher tumor-to-background ratios than SSTR-PET. Two patients who were positive on [18F]FDG-PET were missed by CXCR4-PET, in the remainder [68Ga]Pentixafor detected an equal (n=2) or higher (n=2) number of lesions. CXCR4 expression of tumor lesions could be confirmed by immunohistochemistry. Non-invasive imaging of CXCR4 expression in SCLC is feasible. [68Ga]Pentixafor as a novel PET tracer might serve as readout for confirmation of CXCR4 expression as prerequisite for potential CXCR4-directed treatment including receptor-radio(drug)peptide therapy.

Estrogen effects in the heart.

Gender specific differences in cardiovascular disease are largely mediated by sex hormones. The use of estrogens significantly reduces the overall incidence of heart disease in postmenopausal women. Beneficial effects of estrogens on plasma lipoprotein levels are clearly established. However, these do not explain the magnitude of risk reduction seen in clinical studies. Thus, additional and currently unknown functions of estrogens must be operative. Elucidation of the exact estrogen action in the heart will have important implications in the treatment of cardiovascular disease. It will probably enhance the therapeutic repertoire in treating heart disease, the most common cause of death in industrialized countries. We will review the current understanding of the function of estrogens in the heart and discuss potential strategies on how to apply these data to clinical practice.

Estrogen and estrogen receptors in cardiovascular oxidative stress

The cardiovascular system of a premenopausal woman is prepared to adapt to the challenges of increased cardiac output and work load that accompany pregnancy. Thus, it is tempting to speculate whether enhanced adaptability of the female cardiovascular system might be advantageous under conditions that promote cardiovascular disease. In support of this concept, 17β-estradiol as the major female sex hormone has been shown to confer protective cardiovascular effects in experimental studies. Mechanistically, these have been partially linked to the prevention and protection against oxidative stress. Current evidence indicates that estrogens attenuate oxidative stress at two levels: first, by preventing generation of reactive oxygen species (ROS) and, second, by scavenging ROS in the myocardium and in the vasculature. The purpose of this review is to give an overview on current concepts on conditions and mechanisms by which estrogens protect the cardiovascular system against ROS-mediated cellular injury.