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.

Post-Transcriptional and Epigenetic Regulation of Estrogen Signaling

Post-translational and epigenetic regulation are important mechanisms controlling functions of genes and proteins. Although the "classic" estrogen receptors (ERs) have been acknowledged to function in mediating estrogen effects via transcriptional mechanisms, estrogenic agents modulate the turnover of several proteins via post-transcriptional and post-translational pathways including epigenetics. For instance, the metabolic and angiogenic action of G-protein coupled estrogen receptor (GPER) in vascular endothelial cells has been recently elucidated. By interacting with GPER, 17β-estradiol and the GPER agonist G1 enhance endothelial stability of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and capillary tube formation by increasing ubiquitin-specific peptidase 19 levels, thereby reducing PFKFB3 ubiquitination and proteasomal degradation. In addition to ligands, the functional expression and trafficking of ERs can be modulated by post-translational modification, including palmitoylation. MicroRNAs (miRNAs), the most abundant form of endogenous small RNAs in humans, regulate multiple target genes and are at the center of the multi-target regulatory network. This review also discusses the emerging evidence of how miRNAs affect glycolytic metabolism in cancer, as well as their regulation by estrogens. Restoring dysregulated miRNA expression represents a promising strategy to counteract the progression of cancer and other disease conditions. Accordingly, estrogen post-transcriptional regulatory and epigenetic mechanisms represent novel targets for pharmacological and nonpharmacological intervention for the treatment and prevention of hormone-sensitive noncommunicable diseases, including estrogen-sensitive cancers of the reproductive system in women. SIGNIFICANCE STATEMENT: The effects of estrogen are mediated by several mechanisms that are not limited to the transcriptional regulation of target genes. Slowing down the turnover of master regulators of metabolism by estrogens allows cells to rapidly adapt to environmental cues. Identification of estrogen-targeted microRNAs may lead to the development of novel RNA therapeutics that disrupt pathological angiogenesis in estrogen-dependent cancers.

The G protein-coupled oestrogen receptor GPER in health and disease: an update

Oestrogens and their receptors contribute broadly to physiology and diseases. In premenopausal women, endogenous oestrogens protect against cardiovascular, metabolic and neurological diseases and are involved in hormone-sensitive cancers such as breast cancer. Oestrogens and oestrogen mimetics mediate their effects via the cytosolic and nuclear receptors oestrogen receptor-α (ERα) and oestrogen receptor-β (ERβ) and membrane subpopulations as well as the 7-transmembrane G protein-coupled oestrogen receptor (GPER). GPER, which dates back more than 450 million years in evolution, mediates both rapid signalling and transcriptional regulation. Oestrogen mimetics (such as phytooestrogens and xenooestrogens including endocrine disruptors) and licensed drugs such as selective oestrogen receptor modulators (SERMs) and downregulators (SERDs) also modulate oestrogen receptor activity in both health and disease. Following up on our previous Review of 2011, we herein summarize the progress made in the field of GPER research over the past decade. We will review molecular, cellular and pharmacological aspects of GPER signalling and function, its contribution to physiology, health and disease, and the potential of GPER to serve as a therapeutic target and prognostic indicator of numerous diseases. We also discuss the first clinical trial evaluating a GPER-selective drug and the opportunity of repurposing licensed drugs for the targeting of GPER in clinical medicine.

Automated detection, delineation and quantification of whole-body bone metastasis using FDG-PET/CT images

Non-small cell lung cancer (NSCLC) patients with the metastatic spread of disease to the bone have high morbidity and mortality. Stereotactic ablative body radiotherapy increases the progression free survival and overall survival of these patients with oligometastases. FDG-PET/CT, a functional imaging technique combining positron emission tomography (PET) with 18 F-fluorodeoxyglucose (FDG) and computer tomography (CT) provides improved staging and identification of treatment response. It is also associated with reduction in size of the radiotherapy tumour volume delineation compared with CT based contouring in radiotherapy, thus allowing for dose escalation to the target volume with lower doses to the surrounding organs at risk. FDG-PET/CT is increasingly being used for the clinical management of NSCLC patients undergoing radiotherapy and has shown high sensitivity and specificity for the detection of bone metastases in these patients. Here, we present a software tool for detection, delineation and quantification of bone metastases using FDG-PET/CT images. The tool extracts standardised uptake values (SUV) from FDG-PET images for auto-segmentation of bone lesions and calculates volume of each lesion and associated mean and maximum SUV. The tool also allows automatic statistical validation of the auto-segmented bone lesions against the manual contours of a radiation oncologist. A retrospective review of FDG-PET/CT scans of more than 30 candidate NSCLC patients was performed and nine patients with one or more metastatic bone lesions were selected for the present study. The SUV threshold prediction model was designed by splitting the cohort of patients into a subset of 'development' and 'validation' cohorts. The development cohort yielded an optimum SUV threshold of 3.0 for automatic detection of bone metastases using FDG-PET/CT images. The validity of the derived optimum SUV threshold on the validation cohort demonstrated that auto-segmented and manually contoured bone lesions showed strong concordance for volume of bone lesion (r = 0.993) and number of detected lesions (r = 0.996). The tool has various applications in radiotherapy, including but not limited to studies determining optimum SUV threshold for accurate and standardised delineation of bone lesions and in scientific studies utilising large patient populations for instance for investigation of the number of metastatic lesions that can be treated safety with an ablative dose of radiotherapy without exceeding the normal tissue toxicity.

Challenges in the evaluation of endothelial cell dysfunction: a statement from the European Society of Hypertension Working Group on Endothelin and Endothelial Factors

Endothelial cell function is mediated by different mechanisms in different vascular beds. Moreover, in humans, endothelial cell dysfunction triggers and accelerates the progression of cardiovascular and chronic kidney diseases. Progression of such diseases can be in part mitigated by the control of cardiovascular risk factors and drugs targeting different systems, including endothelin receptor antagonists (ERAs), renin-angiotensin aldosterone antagonists and agents affecting glucose metabolism, all of which were shown to improve endothelial cell function. In recent years, the microRNAs, which are endogenous regulators of gene expression, have been identified as transmitters of information from endothelial cells to vascular smooth muscle cells, suggesting that they can entail tools to assess the endothelial cell dysfunction in arterial hypertension and target for pharmacologic intervention. This article critically reviews current challenges and limitations of available techniques for the invasive and noninvasive assessment of endothelial cell function, and also discusses therapeutic aspects as well as directions for future research in the areas of endothelial cell biology and pathophysiology in humans.

Endothelium and endothelin: regulators of arterial stiffness and fibrinolysis in ANCA-associated vasculitis

In this issue, Farrah et al. report clinical investigations in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). They demonstrate that endothelium-dependent vasodilatation, fibrinolytic capacity, and monocyte-dependent endothelin-1 clearance are reduced in patients with AAV, whereas circulating levels of endothelin-1 and vascular stiffness are increased. Acute infusion of an endothelin ET_A receptor antagonist reduced vasoconstriction and arterial stiffness. This Commentary discusses biological insights and clinical implications of this study.

Serum from Patients with Severe Alcoholic Liver Cirrhosis Inhibits Proliferation and Migration of Human Coronary Artery Smooth Muscle Cells

Liver cirrhosis has been associated with an increased risk of coronary artery disease and clinical complications following percutaneous coronary revascularization. The present study is based on the hypothesis that cirrhosis may influence intimal hyperplasia following PCI. Sera from 10 patients with alcoholic liver cirrhosis and 10 age-matched healthy controls were used to stimulate cultured human coronary artery smooth muscle cells (HCASMC) for 48 h. HCASMC proliferation, migration, gene expression and apoptosis were investigated. Serum concentrations of growth factors and markers of liver function were also determined in patients and healthy controls. Treatment of HCASMC with patient sera reduced cell proliferation and migration (p < 0.05 vs. healthy controls), whereas apoptosis was unaffected (p = 0.160). Expression of genes associated with a synthetic vascular smooth muscle cell phenotype was decreased in cells stimulated with serum from cirrhotic patients (RBP1, p = 0.001; SPP1, p = 0.003; KLF4, p = 0.004). Platelet-derived growth factor-BB serum concentrations were lower in patients (p = 0.001 vs. controls). The results suggest the presence of circulating factors in patients with alcoholic liver cirrhosis affecting coronary smooth muscle cell growth. These findings may have implications for clinical outcomes following percutaneous coronary revascularization in these patients.

Clinical Efficacy and Safety of Angiogenesis Inhibitors: Sex Differences and Current Challenges

Vasoactive molecules, such as vascular endothelial growth factor (VEGF) and endothelins, share cytokine-like activities and regulate endothelial cell (EC) growth, migration and inflammation. Some endothelial mediators and their receptors are targets for currently approved angiogenesis inhibitors, drugs that are either monoclonal antibodies raised towards VEGF, or inhibitors of vascular receptor protein kinases and signaling pathways. Pharmacological interference with the protective functions of ECs results in a similar spectrum of adverse effects. Clinically, the most common side effects of VEGF signaling pathway inhibition include an increase in arterial pressure, left ventricular (LV) dysfunction ultimately causing heart failure, and thromboembolic events, including pulmonary embolism, stroke, and myocardial infarction. Sex steroids such as androgens, progestins, and estrogen and their receptors (ERα, ERβ, GPER; PR-A, PR-B; AR) have been identified as important modifiers of angiogenesis, and sex differences have been reported for anti-angiogenic drugs. This review article discusses the current challenges clinicians are facing with regard to angiogenesis inhibitor treatments, including the need to consider sex differences affecting clinical efficacy and safety. We also propose areas for future research taking into account the role of sex hormone receptors and sex chromosomes. Development of new sex-specific drugs with improved target and cell-type selectivity likely will open the way personalized medicine in men and women requiring antiangiogenic therapy and result in reduced adverse effects and improved therapeutic efficacy.

Potential harmful effects of discontinuing ACE-inhibitors and ARBs in COVID-19 patients

The discovery of angiotensin converting enzyme-2 (ACE-2) as the receptor for SARS- CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2) has implicated the renin-angiotensin-aldosterone system in acute respiratory distress syndrome (ARDS) and respiratory failure in patients with coronavirus disease-19 (COVID-19). The angiotensin converting enzyme-1-angiotensin II-angiotensin AT1 receptor pathway contributes to the pathophysiology of ARDS, whereas activation of the ACE-2-angiotensin(1-7)-angiotensin AT2 receptor and the ACE-2-angiotensin(1-7)-Mas receptor pathways have been shown to be protective. Here we propose and discuss therapeutic considerations how to increase soluble ACE-2 in plasma in order for ACE-2 to capture and thereby inactivate SARS-CoV-2. This could be achieved by administering recombinant soluble ACE-2. We also discuss why and how ACEIs and ARBs provide cardiovascular, renal and also pulmonary protection in SARS-CoV-2- associated ARDS. Discontinuing these medications in COVID-19 patients may therefore potentially be harmful.

Factors Associated With Radiotherapy Utilisation In New South Wales, Australia: Results From The 45 and Up Study

AIMS

Actual radiotherapy utilisation rates tend to be lower than the estimated optimal rates. Little is known about the factors contributing to this difference. Our aim was to identify factors associated with radiotherapy receipt for a cohort of cancer patients in New South Wales (NSW), Australia.

MATERIALS AND METHODS

In total, 267 153 participants in the NSW 45 and Up Study completed a questionnaire during 2006-2009 providing detailed health and socio-demographic information and consented to record linkage with administrative health datasets. Single primary cancers diagnosed after study enrolment were identified through linkage with the NSW Cancer Registry to December 2013. Radiotherapy receipt was determined from claims to the Medicare Benefits Schedule and/or records in the NSW Admitted Patient Data Collection (2006 to June 2016). Competing risks regression was used to examine associations between health and socio-demographic characteristics and radiotherapy treatment.

RESULTS

Of 17 873 patients with an incident cancer, 5414 (30.3%) received radiotherapy during follow-up (median 5.3 years). Patients less likely to receive radiotherapy were aged <60 or 80+ years, female, had a Charlson co-morbidity index of 1+, needed help with daily tasks or lived ≥100 km from the nearest radiotherapy centre.

CONCLUSION

Distinct subgroups of patients are less likely to receive radiotherapy. Advocacy and/or policy changes are needed to improve access.

Endothelin: 30 Years From Discovery to Therapy

Discovered in 1987 as a potent endothelial cell-derived vasoconstrictor peptide, endothelin-1 (ET-1), the predominant member of the endothelin peptide family, is now recognized as a multifunctional peptide with cytokine-like activity contributing to almost all aspects of physiology and cell function. More than 30 000 scientific articles on endothelin were published over the past 3 decades, leading to the development and subsequent regulatory approval of a new class of therapeutics-the endothelin receptor antagonists (ERAs). This article reviews the history of the discovery of endothelin and its role in genetics, physiology, and disease. Here, we summarize the main clinical trials using ERAs and discuss the role of endothelin in cardiovascular diseases such as arterial hypertension, preecclampsia, coronary atherosclerosis, myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) caused by spontaneous coronary artery dissection (SCAD), Takotsubo syndrome, and heart failure. We also discuss how endothelins contributes to diabetic kidney disease and focal segmental glomerulosclerosis, pulmonary arterial hypertension, as well as cancer, immune disorders, and allograft rejection (which all involve ET_A autoantibodies), and neurological diseases. The application of ERAs, dual endothelin receptor/angiotensin receptor antagonists (DARAs), selective ET_B agonists, novel biologics such as receptor-targeting antibodies, or immunization against ET_A receptors holds the potential to slow the progression or even reverse chronic noncommunicable diseases. Future clinical studies will show whether targeting endothelin receptors can prevent or reduce disability from disease and improve clinical outcome, quality of life, and survival in patients.

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.

P6555A self-adaptive approach to antitachycardia pacing - a head to head comparison using advanced computational modeling

Background

Antitachycardia pacing (ATP) for monomorphic VT (MVT) reduces painful defibrillation shocks. Most ICD-treated ventricular arrhythmias are MVT, suggesting an opportunity for improved ATP to decrease shocks. We report on a new algorithm (Yee, Circ AE 2017) that uses electrophysiologic (EP) first-principles to design ATP sequences in real-time. Heart-rate history is used to design the first ATP sequence, and failed ATP post-pacing interval is used to design later sequences.

Purpose

The purpose of this modeling study was to understand how this new ATP algorithm would perform in a head-to-head comparison with traditional burst ATP. Modeling allows direct comparison of the two algorithms in identical, realistic, patient-derived cardiac arrythmias.

Methods

Patient-specific late gadolinium enhanced MRI and EP data were used to build an adjudicated cohort of realistic numerical heart models with varied EP, infarct, border zone. Publicly available EP modeling software CARPentry was used to calculate sustained reentrant VT initiated with the programmed electrical stimulation used to induce VT clinically. The VTs were physician-adjudicated to validate models. Burst ATP was 3 sequences of 8 pulses at 88% of VT cycle length, each decremented by 10ms. The new ATP was limited to 3 automatically designed sequences.

Results

Three hundred unique VT scenarios were generated from 6 human hearts with multiple VT circuits, 5 electrophysiologic states, and 10 pacing locations. Burst ATP terminated 168/300 VTs (56%) and accelerated 2.7%. The new ATP terminated 234/300 VTs (78%) with the same acceleration. The two dominant ATP failure mechanisms were identified as 1) insufficient prematurity to close the excitable gap, and 2) failure to reach the critical isthmus of the VT circuit. For these mechanisms, the new ATP algorithm reduce failures from 64 to 28 (44% reduction) without increasing acceleration.

Conclusion

The new automated ATP algorithm successfully adapted ATP sequences for VT episodes that burst ATP failed to terminate. The new ATP was successful even with complex scar geometries and electrophysiology heterogeneity as seen in the real world.

Abstract P261: GPER is Required for Age-dependent Albuminuria and Glomerulosclerosis: Evidence for its Role in Podocyte Injury and Mesangial Nox1 Regulation

We recently found that the G-protein coupled estrogen receptor (GPER) exerts constitutive effects on cell proliferation and fibrosis in heart failure and arterial hypertension via the NADPH oxidase isoform Nox1 (Sci Signal 2016; 9(452): ra105). Whether GPER affects glomerulosclerosis or podocyte function is unknown. Thus, the present study investigated the effects of GPER in a model of age-dependent spontaneous focal segmental glomerulosclerosis and studied effects of GPER inhibition in mesangial cells and podocytes. Albuminuria and kidney histology were studied in male wild-type (WT) and GPER-deficient ( Gper -/- ) mice at 4 and 24 months of age. Aged Gper -/- mice were largely protected from albuminuria (albumin/creatinine-ratio, 0.9±0.4 vs. 3.5±1.0, -74 %, p<0.05 vs. WT). Gper deficiency had no effect at 4 months of age, but largely prevented age-dependent increases in kidney weight (306±11 vs. 554±94 mg), and glomerulosclerosis index (1.3±0.2 vs. 2.9±0.4, p<0.05 vs. WT). All changes were independent of blood pressure. In human podocytes exposed to TGFβ-1, treatment with the selective GPER blocker G36 markedly reduced mRNA expression of injury markers nephrin, collagen-4, and Wilms-tumor-1 (all p<0.01). Gper knock-down in rat mesangial cells reduced Nox1 protein expression by approx. 50% (p<0.05) while Nox2 and Nox4 expression remained unchanged. These results indicate that constitutive activity of Gper maintains Nox1 expression and contributes to podocyte injury in vitro and that Gper is essential for age-dependent podocyte injury, subsequent albuminuria, fibrosis and glomerulosclerosis in vivo. Nox1 downregulators such as G36 represent a new class of drugs that may offer therapeutic potential for patients with chronic renal diseases and other forms of chronic non-communicable diseases involving inflammation and fibrosis.

Sidney George Shaw, DPhil (1948-2017)

On March 4, 2017 at the age of 68, Sidney George Shaw (Sid) unexpectedly died from complications following surgery, only four years after retiring from the University of Bern. Trained in biochemistry at Oxford University, Sid had quickly moved into molecular pharmacology and became a key investigator in the field of enzyme biochemistry, vasoactive peptide research, and receptor signaling. Sid spent half his life in Switzerland, after moving to the University of Bern in 1984. This article, written by his friends and colleagues who knew him and worked with him during different stages of his career, summarizes his life, his passions, and his achievements in biomedical research. It also includes personal memories relating to a dear friend and outstanding scientist whose intellectual curiosity, humility, and honesty will remain an example to us all.

Olfactory Ensheathing Cells for Spinal Cord Injury: Sniffing Out the Issues

Olfactory ensheathing cells (OECs) are glia reported to sustain the continuous axon extension and successful topographic targeting of the olfactory receptor neurons responsible for the sense of smell (olfaction). Due to this distinctive property, OECs have been trialed in human cell transplant therapies to assist in the repair of central nervous system injuries, particularly those of the spinal cord. Though many studies have reported neurological improvement, the therapy remains inconsistent and requires further improvement. Much of this variability stems from differing olfactory cell populations prior to transplantation into the injury site. While some studies have used purified cells, others have used unpurified transplants. Although both preparations have merits and faults, the latter increases the variability between transplants received by recipients. Without a robust purification procedure in OEC transplantation therapies, the full potential of OECs for spinal cord injury may not be realised.

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.

GPER Mediates Functional Endothelial Aging in Renal Arteries

Aging is associated with impaired renal artery function, which is partly characterized by arterial stiffening and a reduced vasodilatory capacity due to excessive generation of reactive oxygen species by NADPH oxidases (Nox). The abundance and activity of Nox depends on basal activity of the heptahelical transmembrane receptor GPER; however, whether GPER contributes to age-dependent functional changes in renal arteries is unknown. This study investigated the effect of aging and Nox activity on renal artery tone in wild-type and GPER-deficient (Gper-/-) mice (4 and 24 months old). In wild-type mice, aging markedly impaired endothelium-dependent, nitric oxide (NO)-mediated relaxations to acetylcholine, which were largely preserved in renal arteries of aged Gper-/- mice. The Nox inhibitor gp91ds-tat abolished this difference by greatly enhancing relaxations in wild-type mice, while having no effect in Gper-/- mice. Contractions to angiotensin II and phenylephrine in wild-type mice were partly sensitive to gp91ds-tat but unaffected by aging. Again, deletion of GPER abolished effects of Nox inhibition on contractile responses. In conclusion, basal activity of GPER is required for the age-dependent impairment of endothelium-dependent, NO-mediated relaxation in the renal artery. Restoration of relaxation by a Nox inhibitor in aged wild-type but not Gper-/- mice strongly supports a role for Nox-derived reactive oxygen species as the underlying cause. Pharmacological blockers of GPER signaling may thus be suitable to inhibit functional endothelial aging of renal arteries by reducing Nox-derived oxidative stress and, possibly, the associated age-dependent deterioration of kidney function.

Technical Note: Experimental results from a prototype high-field inline MRI-linac

PURPOSE

The pursuit of real-time image guided radiotherapy using optimal tissue contrast has seen the development of several hybrid magnetic resonance imaging (MRI)-treatment systems, high field and low field, and inline and perpendicular configurations. As part of a new MRI-linac program, an MRI scanner was integrated with a linear accelerator to enable investigations of a coupled inline MRI-linac system. This work describes results from a prototype experimental system to demonstrate the feasibility of a high field inline MR-linac.

METHODS

The magnet is a 1.5 T MRI system (Sonata, Siemens Healthcare) was located in a purpose built radiofrequency (RF) cage enabling shielding from and close proximity to a linear accelerator with inline (and future perpendicular) orientation. A portable linear accelerator (Linatron, Varian) was installed together with a multileaf collimator (Millennium, Varian) to provide dynamic field collimation and the whole assembly built onto a stainless-steel rail system. A series of MRI-linac experiments was performed to investigate (1) image quality with beam on measured using a macropodine (kangaroo) ex vivo phantom; (2) the noise as a function of beam state measured using a 6-channel surface coil array; and (3) electron contamination effects measured using Gafchromic film and an electronic portal imaging device (EPID).

RESULTS

(1) Image quality was unaffected by the radiation beam with the macropodine phantom image with the beam on being almost identical to the image with the beam off. (2) Noise measured with a surface RF coil produced a 25% elevation of background intensity when the radiation beam was on. (3) Film and EPID measurements demonstrated electron focusing occurring along the centerline of the magnet axis.

CONCLUSIONS

A proof-of-concept high-field MRI-linac has been built and experimentally characterized. This system has allowed us to establish the efficacy of a high field inline MRI-linac and study a number of the technical challenges and solutions.

Abstract P1-08-06: BC200 lncRNA is involved in the progression of triple negative breast cancer

Long non coding RNAs (lncRNAs) have been identified as regulators of the cell cycle, apoptosis, and DNA damage among other processes that if deregulated, may lead to cancer by acting as proto-oncogenes, tumor suppressor genes, and drivers of metastatic transformation. Using RNA sequencing we have identified 42 differentially expressed lncRNAs from a healthy cohort of parous vs. nulliparous women. After bioinformatics and RT-qPCR analysis, we have focused on a vaguely studied lncRNA called BC200 that is highly expressed in the nulliparous postmenopausal breast tissue. It is known that BC200 lncRNA is overexpressed in invasive and pre-invasive breast cancer; however, its functional role in the initiation and progression of breast cancer is poorly understood. In the present work we provide insight on the role of BC200 in the context of luminal and triple negative breast cancer (TNBC). We have confirmed that BC200 is highly expressed in breast cancer tissue and in widely used breast cancer cell lines such as MCF7, T47D, MDAMB231, and Hs578T. Using a lentiviral system we successfully obtained cell lines which stably express BC200. Overexpression of BC200 increases proliferation, migration, and invasion potential in vitro in the cell lines tested, specifically luminal T47D and TNBC MDAMB231. Xenograft studies performed in the mammary fat pad of female SCID mice confirm the role of BC200 as a tumor promoter. Tumors in mice injected with MDAMB231 cells overexpressing BC200 were 4.5 times bigger than tumors in the control group in only 6 weeks when injecting 1 million cells. Moreover, we have determined, using reverse transcriptase PCR targeting genes less than 200 kb from the start site of BC200, that when BC200 is overexpressed, CALM2 is downregulated in both T47D and MDAMB231 cell lines. CALM2 or Calmodulin is a calcium binding protein that plays a role in signaling pathways, cell cycle progression, proliferation, and apoptosis. Mutations in CALM2 are associated with increased risk of breast cancer. Our positive results on Cis regulation are being expanded using chromatin isolation by RNA immunoprecipitation to determine BC200's genome wide regulation.

These results demonstrate the participation of BC200 lncRNA in the progression of breast cancer. Notably, BC200 regulates nearby genes that have an implication in cancer progression. BC200, identified in the normal breast tissue of nulliparous women, not only plays a key role in breast cancer progression but also provides a new insight in the preventive role of pregnancy by the downregulation of the expression of this lncRNA in the normal parous breast. [This work was supported by the NCI (National Cancer Institute) Core Grant CA06927 to Fox Chase Cancer Center and generous support from Christian - Diane Martin, the Flyers Wives, and Joseph - Barbara Breitman to Dr. J. Russo, MD].

Citation Format: Barton M, Santucci-Pereira J, Su Y, Russo J. BC200 lncRNA is involved in the progression of triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-08-06.