Unmasking a new prognostic marker and therapeutic target from the GDNF-RET/PIT1/p14ARF/p53 pathway in acromegaly.

BACKGROUND: Acromegaly is produced by excess growth hormone secreted by a pituitary adenoma of somatotroph cells (ACRO). First-line therapy, surgery and adjuvant therapy with somatostatin analogs, fails in 25% of patients. There is no predictive factor of resistance to therapy. New therapies are investigated using few dispersed tumor cells in acute primary cultures in standard conditions where the cells do not grow, or using rat pituitary cell lines that do not maintain the full somatotroph phenotype. The RET/PIT1/p14ARF/p53 pathway regulates apoptosis in normal pituitary somatotrophs whereas the RET/GDNF pathway regulates survival, controlling PIT1 levels and blocking p14ARF (ARF) and p53 expression. METHODS: We investigated these two RET pathways in a prospective series of 32 ACRO and 63 non-functioning pituitary adenomas (NFPA), studying quantitative RNA and protein gene expression for molecular-clinical correlations and how the RET pathway might be implicated in therapeutic success. Clinical data was collected during post-surgical follow-up. We also established new'humanized' pituitary cultures, allowing 20 repeated passages and maintaining the pituitary secretory phenotype, and tested five multikinase inhibitors (TKI: Vandetanib, Lenvatinib, Sunitinib, Cabozantinib and Sorafenib) potentially able to act on the GDNF-induced RET dimerization/survival pathway. Antibody arrays investigated intracellular molecular pathways. FINDINGS: In ACRO, there was specific enrichment of all genes in both RET pathways, especially GDNF. ARF and GFRA4 gene expression were found to be opposing predictors of response to first-line therapy. ARF cut-off levels, calculated categorizing by GNAS mutation, were predictive of good response (above) or resistance (below) to therapy months later. Sorafenib, through AMPK, blocked the GDNF/AKT survival action without altering the RET apoptotic pathway. INTERPRETATION: Tumor ARF mRNA expression measured at the time of the surgery is a prognosis factor in acromegaly. The RET inhibitor, Sorafenib, is proposed as a potential treatment for resistant ACRO. FUND: This project was supported by national grants from Agencia Estatal de Investigación (AEI) and Instituto Investigación Carlos III, with participation of European FEDER funds, to IB (PI150056) and CVA (BFU2016-76973-R). It was also supported initially by a grant from the Investigator Initiated Research (IIR) Program (WI177773) and by a non-restricted Research Grant from Pfizer Foundation to IB. Some of the pituitary acromegaly samples were collected in the framework of the Spanish National Registry of Acromegaly (REMAH), partially supported by an unrestricted grant from Novartis to the Spanish Endocrine Association (SEEN). CVA is also supported from a grant of Medical Research Council UK MR/M018539/1.

Metabolic alterations derived from absence of Two-Pore Channel 1 at cardiac level.

Two-pore channels (TPCs or TPCNs) are novel voltage-gated ion channels that have been postulated to act as Ca2+ and/or Na+ channels expressed exclusively in acidic organelles such as endosomes and lysosomes. TPCNs participate in the regulation of diverse biological processes and recently have been proposed to be involved in the pathophysiology of metabolic disorders such as obesity, fatty liver disease and type 2 diabetes mellitus. Due to the importance of these pathologies in the development of cardiovascular diseases, we aimed to study the possible role of two-pore channel 1 (TPCN1) in the regulation of cardiac metabolism. To explore the cardiac function of TPCN1, we developed proteomic approaches as 2-DE-MALDI-MS and LC-MALDI-MS in the cardiac left ventricle of TPCN1 KO and WT mice, and found alterations in several proteins implicated in glucose and fatty acid metabolism in TPCN1 KO vs. WT mice. The results confirmed the altered expression of HFABP, a key fatty acid transport protein, and of enolase and PGK1, the key enzymes in the glycolytic process. Finally, in vitro experiments performed in neonatal rat cardiomyocytes, in which TPCN1 was silenced using siRNAs, confirmed that the downregulation of TPCN1 gene expression increased 2-deoxy-D-[3H]-glucose uptake and GLUT4 mobilization into cell peripherals in cardiac cells. Our results are the first to suggest a potential role for TPCNs in cardiac metabolism regulation.

Absence of intracellular ion channels TPC1 and TPC2 leads to mature-onset obesity in male mice, due to impaired lipid availability for thermogenesis in brown adipose tissue.

Intracellular calcium-permeable channels have been implicated in thermogenic function of murine brown and brite/beige adipocytes, respectively transient receptor potential melastin-8 and transient receptor potential vanilloid-4. Because the endo-lysosomal two-pore channels (TPCs) have also been ascribed with metabolic functionality, we studied the effect of simultaneously knocking out TPC1 and TPC2 on body composition and energy balance in male mice fed a chow diet. Compared with wild-type mice, TPC1 and TPC2 double knockout (Tpcn1/2(-/-)) animals had a higher respiratory quotient and became obese between 6 and 9 months of age. Although food intake was unaltered, interscapular brown adipose tissue (BAT) maximal temperature and lean-mass adjusted oxygen consumption were lower in Tpcn1/2(-/-) than in wild type mice. Phosphorylated hormone-sensitive lipase expression, lipid density and expression of ß-adrenergic receptors were also lower in Tpcn1/2(-/-) BAT, whereas mitochondrial respiratory chain function and uncoupling protein-1 expression remained intact. We conclude that Tpcn1/2(-/-) mice show mature-onset obesity due to reduced lipid availability and use, and a defect in ß-adrenergic receptor signaling, leading to impaired thermogenic activity, in BAT.

Review of novel aspects of the regulation of ghrelin secretion.

The role of ghrelin in regulating metabolism and energy balance has been a subject of intense focus ever since its discovery. Ghrelin regulates energy balance in the short term by induction of appetite and in the longer term by increasing body weight and adiposity. It is the only known peripheral orexigenic hormone and one of the most potent endogenous orexigenic factors discovered to date. However, whilst extensively studied, the mechanism of ghrelin secretion is not well understood. A better understanding of the pathways controlling ghrelin secretion could be useful in the development of new therapeutic approaches to appetite-related disorders. Here, we discuss current knowledge of the processes that control ghrelin secretion, focusing on neural, chemical and hormonal stimuli. In addition, we share our view on the potential of targeting ghrelin for the treatment of eating disorders such as obesity, anorexia nervosa and cachexia.

Pro B-type natriuretic peptide plasma value: a new criterion for the prediction of short- and long-term outcomes after transcatheter aortic valve implantation.

BACKGROUND: To determine the prognostic value of pro B-type natriuretic peptide (pro-BNP) to predict mortality after transcatheter aortic valve implantation (TAVI). Logistic EuroSCORE (LES) overestimates observed mortality after TAVI. A new risk score specific to TAVI is needed to accurately assess mortality and outcome. METHODS: Eighty-five patients were included. Indications for TAVI were nonoperable or surgically high-risk patients (LES>20%). Pro-BNP was measured 24h before the procedure. Cox proportional hazards model was used to evaluate clinical factors. The predictive accuracy of these Cox models was determined by using time-dependent receiver operating characteristic (ROC) curves. RESULTS: Pro-BNP levels (log-transformed) were significantly higher in non-survivors than in survivors at 30 days (3.36 ± 0.43 vs. 3.81 ± 0.43, p<0.004) and at the end of follow-up (3.34 ± 0.42 vs. 3.63 ± 0.48, p<0.011). Multivariate analysis revealed that only increased log pro-BNP levels were associated with higher mortality rate at short [hazard ratio (HR) (95% confidence intervals (CI)]=5.35 (1.74-16.5), p=0.003] and long-term follow-ups [HR=11 (CI: 1.51-81.3), p=0.018]. LES was not associated with increased mortality at either time point [HR=1.03 (CI: 0.95-1.10), p=0.483 and HR=1.03 (CI: 0.98-1.07), p=0.230, respectively]. At 30, 90, 180, and 365 days, the c-index was 0.72 for log pro-BNP and 0.63 for LES (p=0.044). CONCLUSION: Pre-procedure log transform of plasma pro-BNP levels are an independent and strong predictor of short- and long-term outcomes after TAVI and are more discriminatory than LES.

Defining stem cell types: understanding the therapeutic potential of ESCs, ASCs, and iPS cells.

Embryonic, adult, artificially reprogrammed, and cancer…- there are various types of cells associated with stemness. Do they have something fundamental in common? Are we applying a common name to very different entities? In this review, we will revisit the characteristics that define 'pluripotency', the main property of stem cells (SCs). For each main type of physiological (embryonic and adult) or synthetic (induced pluripotent) SCs, markers and functional behavior in vitro and in vivo will be described. We will review the pioneering work that has led to obtaining human SC lines, together with the problems that have arisen, both in a biological context (DNA alterations, heterogeneity, tumors, and immunogenicity) and with regard to ethical concerns. Such problems have led to proposals for new operative procedures for growing human SCs of sufficiently high quality for use as models of disease and in human therapy. Finally, we will review the data from the first clinical trials to use various types of SCs.

Aliskiren affects fatty-acid uptake and lipid-related genes in rodent and human cardiomyocytes.

PURPOSE: We investigated whether the direct renin inhibitor aliskiren can affect metabolism in cardiomyocytes from rat, mouse and human sources. METHODS AND RESULTS: At 10-50 µmol/L, aliskiren significantly increased medium-chain-fatty-acid uptake in primary-cultured neonatal-rat and HL-1 adult-mouse-derived cardiomyocytes (BODIPY-induced fluorescence intensity). The fatty-acid transporter CD-36 was correspondingly translocated to, but the glucose transporter Glut-4 away from, the sarcoplasmic reticulum/plasma membrane, in primary-cultured neonatal-rat (CD-36, Glut-4) and adult-human (CD-36) cardiomyocytes (confocal immunocytochemistry). Immunoblotting showed that aliskiren induced phosphorylation of ERK1/2 in cardiomyocytes from all three sources; responses were dose- and time-dependent, unaffected by renin treatment, and did not cause alterations in expression of (P)R or Igf2/M6P receptors. Microarray analysis of the complete genome of aliskiren-treated neonatal-rat cardiomyocytes, with RT-qPCR and immunoblot confirmation assays in rat and human primary cardiomyocytes, showed that aliskiren up-regulated mRNA and increased protein expression of several enzymes important in lipid and glucose metabolism and in cholesterol biosynthesis. Cardiomyocyte cell-cycle and viability were unaffected by aliskiren. CONCLUSIONS: Aliskiren can induce changes in fatty-acid and glucose uptake and expression of key enzymes of lipid and cholesterol metabolism, which are not associated with increased expression of (P)R or Igf2/M6P receptors, in cultured cardiomyocytes.

Prognostic impact of atrial fibrillation progression in a community study: AFBAR Study (Atrial Fibrillation in the Barbanza Area Study).

INTRODUCTION: The aim of the study is to describe the natural history of an unselected population of patients with atrial fibrillation (AF) currently attending primary care services in a single health-service area in Galicia, north-western Spain. METHODS: AFBAR is a transverse prospective study in which 35 general practitioners within one health-service area have enrolled patients diagnosed with AF who presented at their clinics during a three-month recruiting period. Primary endpoints are mortality or hospital admission. Here we report the results of the first 7-month follow-up period. RESULTS: 798 patients (421 male) were recruited; mean age of cohort was 75 years old. Hypertension was the most prevalent risk factor (77%). 87% of the patients were both overweight and obese. Permanent AF was diagnosed in 549 patients (69%). In the follow-up period, 16.4% of the patients underwent a primary endpoint and the overall survival was 98%. The following independent determinants of primary endpoint were identified: change in AF status (Hazard Ratio (HR) 2.89 (95% confidence interval (CI) 1.28-6.55); p=0.011); ischemic heart disease (IHD) (HR 2.78 (95% CI 1.51-5.13); p=0.001); pre-recruitment hospital admission (HR 2.22 (95% CI 1.18-4.19); p=0.013); left ventricular systolic dysfunction (HR 2.19 (95% CI 1.11-4.32); p=0.023); or AF-related complications (HR 1.98 (95% CI 1.10-3.56); p=0.022). CONCLUSIONS: In the first 7-month follow-up period of patients with AF in a primary care setting the study identified several independent risk factors for mortality or hospital admission, i.e. change in AF status, ischemic heart disease, left ventricular systolic dysfunction, previous AF-related complications and hospital admission.

Des-acyl ghrelin has specific binding sites and different metabolic effects from ghrelin in cardiomyocytes.

The current study aimed to compare the effects of the peptide hormone ghrelin and des-G, its unacylated isoform, on glucose and fatty acid uptake and to identify des-G-specific binding sites in cardiomyocytes. In the murine HL-1 adult cardiomyocyte line, ghrelin and des-G had opposing metabolic effects: des-G increased medium-chain fatty acid uptake (BODIPY fluorescence intensity), whereas neither ghrelin alone nor in combination with des-G did so. Ghrelin inhibited the increase in glucose uptake normally induced by insulin (rate of 2-[(3)H]deoxy-d-glucose incorporation), but des-G did not; des-G was also able to partially reverse the inhibitory effect of ghrelin. In HL-1 cells and primary cultures of neonatal rat cardiomyocytes, des-G but not ghrelin increased insulin-induced translocation of glucose transporter-4 from nuclear to cytoplasmic compartments (immunohistochemistry and quantitative confocal analysis). AKT was phosphorylated by insulin but not affected by ghrelin or des-G, whereas neither AMP-activated protein kinase nor phosphatase and tensin homolog deleted from chromosome 10 was phosphorylated by any treatments. HL-1 and primary-cultured mouse and rat cardiomyocytes each possessed two independent specific binding sites for des-G not recognized by ghrelin (radioreceptor assays). Neither ghrelin nor des-G affected viability (dimethylthiazol diphenyltetrazolium bromide assays), whereas both isoforms were equally protective against apoptosis. Therefore, in cardiomyocytes, des-G binds to specific receptors and has effects on glucose and medium-chain fatty acid uptake that are distinct from those of ghrelin. Real-time PCR indicated that expression levels of ghrelin O-acyltransferase RNA were comparable between HL-1 cells, human myocardial tissue, and human and murine stomach tissue, indicating the possibility of des-G conversion to ghrelin within our model.

Foregut mesenchyme contributes cells to pancreatic acini during embryonic development in a chick-quail chimera model.

To understand causes of developmental abnormalities of the pancreas, it is essential to understand its normal embryonic development. Current understanding of the development of pancreatic exocrine tissue is that it develops solely from embryonic epithelium, while the role of the surrounding mesenchyme is to signal to this epithelium and form connective tissue. Recent work in our laboratory has shown that pancreatic bud mesenchyme can contribute cells to islets during embryonic development. However, no published studies have investigated in detail whether mesenchyme contributes cells to the exocrine structures of the pancreas. The aim of this study was to investigate whether cells from foregut mesenchyme can contribute to pancreatic acini during embryonic development. Chick-quail chimera recombinant organs were constructed using pancreatic epithelium and mesenchyme from either the pancreas (n=12) or stomach (n=25). These were cultured for 7 days in 3-D collagen gels. The resulting specimens were analysed using morphological criteria and fluorescent immunocytochemistry against pancreatic amylase, insulin, and the quail-specific nucleolar antigen QCPN. Two independent observers determined the origins of acini as either solely epithelial, solely mesenchymal, or of mixed origin. Results are expressed as percentages of total acini identified in each group. Statistical analysis was performed using chi(2) tests (P<0.01 was considered statistically significant). Recombinations of pancreatic epithelium and pancreatic mesenchyme yielded 11 acini, of which 45% were derived from epithelium only, 45% from mesenchyme only, and 10% of mixed origin. Recombinations of pancreatic epithelium and stomach mesenchyme yielded 78 acini, of which 40% were derived from epithelium only, 32% from mesenchyme only, and 28% of mixed origin. When acini with any mesenchymal cellular contribution were considered as a group, there was no significant difference between stomach and pancreatic mesenchymal contribution (P=0.72). This is the first study to demonstrate the cellular contribution of mesenchyme to pancreatic exocrine structures. Our data show that mesenchyme contributes cells to pancreatic acini during development in this model and that mesenchyme derived from stomach and pancreatic sources are both able to form acini.

Foregut Mesenchyme Contributes Cells to Islets during Pancreatic Development in a 3-Dimensional Avian Model.

Current interest in the potential use of pancreatic stem-cells in the treatment of insulin dependent diabetes mellitus has led to increased research into normal pancreatic development. Pancreatic organogenesis involves branching morphogenesis of undifferentiated epithelium within surrounding mesenchyme. Current understanding is that the pancreatic islets develop exclusively from the epithelium of the embryonic buds. However, a cellular contribution to islets by mesenchyme has not been conclusively excluded. We present evidence that the mesenchyme of both the dorsal pancreatic bud and stomach rudiment make a substantial contribution of cells to islets during development in a three-dimensional avian model. These data suggest that mesenchyme can be a source not only of signals but also of cells for the definitive epithelia, making pancreatic organogenesis more akin to that of the kidney than to other endodermal organs. This raises the possibility for the use of mesenchymal cells as stem-or progenitor-cells for islet transplantation.