The role of potassium channels in tumours of the gastrointestinal tract: a focus on the human ether-à-go-go related gene 1 channels.

Potassium channels are often dysregulated in tumours of the gastrointestinal (GI) tract. Among them, the voltage-dependent channel KV 11.1, also known as human ether-à-go-go related gene 1 (hERG1), is frequently expressed in tumours and precancerous lesions of the GI tract. In precancerous lesions, hERG1 behaves as a progression factor, contributing to identifying those patients whose lesions can progress towards true cancers. In advanced cancers, such as colorectal and pancreatic cancer, a high hERG1 expression represents a negative prognostic factor, contributing to identifying high risk patients. The only exception is represented by neuroendocrine cancers of both the ileum and the pancreas, where hERG1 represents a positive prognostic factor for survival. In GI tumours, hERG1 can function either as a true channel, allowing outward potassium ion flux and membrane repolarisation, or in a non-canonical, non-conductive way. This occurs because, in cancer, hERG1 forms complexes with different plasma membrane and cytosolic proteins, instead of classical accessory subunits. In particular, hERG1 forms a complex with the ß1 subunit of integrin receptors: the hERG1-ß1 complex. Growth and chemokine receptors, small GTPases, phosphoinositide 3-kinase, as well as other ion transporters or channels, are also recruited in the hERG1-ß1 complex. The formation of multiprotein channel complexes represents an emerging mechanism allowing functional channel networking in both excitable and non-excitable cells. hERG1 represents a prototype of how multiprotein complexes operate in tumours, that is, giving rise to signalling hubs which can transmit and modulate signals arising from the tumour microenvironment, hence contributing to tumour progression and malignancy.

Dynamics and physiological meaning of complexes between ion channels and integrin receptors: the case of Kv11.1.

The cellular functions are regulated by a complex interplay of diffuse and local signals. Studying the latter is challenging, but experimental work in cell physiology has led to recognize that understanding a cell's dynamics requires a deep comprehension of local fluctuations of cytosolic regulators. Macromolecular complexes are major determinants of local signaling. Multienzyme assemblies limit the diffusion restriction to reaction kinetics by direct exchange of metabolites. Likewise, close coupling of ion channels and transporters modulates the ion concentration around a channel mouth or transporter binding site. Extreme signal locality is brought about by conformational coupling between membrane proteins, as is typical of mechanotransduction. A paradigmatic case is integrin-mediated cell adhesion. Sensing the extracellular microenvironment and providing an appropriate response are essential in growth and development and have innumerable pathological implications. The process involves bidirectional signal transduction by complex supramolecular structures that link integrin receptors to ion channels and transporters, growth factor receptors, cytoskeletal elements, and other regulatory elements. The dynamics of such complexes are only beginning to be understood. A thoroughly studied example is the association between integrin receptors and the voltage-gated K+ channels Kv11.1. These channels are widely expressed in early embryos, where their physiological roles are poorly understood and apparently different from the shaping of action potential firing in the adult. Hints about these roles come from studies in cancer cells, where Kv11.1 is often overexpressed and appears to reassume functions it presumably exerts during embryogenesis, such as controlling cell proliferation/differentiation, apoptosis, and migration. Kv11.1 is implicated in these processes through its linking to integrin subunits, which in turn regulates channel expression. Specific cellular functions, such as proliferation and migration, appear to be modulated by distinct conformational states of the channel (e.g., open and closed), whose balance is affected by the link with integrin subunits.

hERG1 Potassium Channel Expression in Colorectal Adenomas: Comparison with Other Preneoplastic Lesions of the Gastrointestinal Tract.

Preneoplastic lesions represent a useful target for early diagnosis and follow-up of gastrointestinal malignancies. hERG1 channel expression was tested by immunohistochemistry (IHC) in a cohort of colorectal adenoma samples belonging to Italian subjects. Overall, hERG1 was expressed in 56.5% of cases with both high staining intensity and a high percentage of positive cells. Moreover, hERG1 was expressed in a higher percentage of dysplastic adenomas with respect to hyperplastic lesions, and the proportion of positive samples further increased in patients with high-grade dysplasia. Comparing hERG1 expression in other preneoplastic lesions of the GI tract (gastric dysplasia and Barrett's esophagus), it emerged that in all the conditions, hERG1 was expressed with a diffused pattern, throughout the cell, with variable staining intensity within the samples. The highest expression was detected in gastric dysplasia samples and the lowest in Barrett's esophagus at similar levels observed in colorectal adenomas. Our results show that hERG1 is aberrantly expressed in human preneoplastic lesions of the gastrointestinal tract and has a different pattern of expression and role in the different sites. Overall, the detection of hERG1 expression in preneoplastic lesions could represent a novel diagnostic or prognostic marker of progression in the gastrointestinal tract.

A unique circulating miRNA profile highlights thrombo-inflammation in Behçet's syndrome.

OBJECTIVES: Behçet's syndrome (BS) is a rare systemic vasculitis often complicated by thrombotic events. Given the lack of validated biomarkers, BS diagnosis relies on clinical criteria.In search of novel biomarkers for BS diagnosis, we determined the profile of plasmatic circulating microRNAs (ci-miRNAs) in patients with BS compared with healthy controls (HCs). METHODS: ci-miRNA profile was evaluated by microarray in a screening cohort (16 patients with BS and 18 HCs) and then validated by poly(T) adaptor PCR (PTA-PCR) in a validation cohort (30 patients with BS and 30 HCs). Two disease control groups (30 patients with systemic lupus erythematosus (SLE) and 30 patients with giant cell arteritis (GCA) were also analysed. RESULTS: From the microarray screening, 29 deregulated (differentially expressed (DE)) human ci-miRNAs emerged. A hierarchical cluster analysis indicated that DE ci-miRNAs clearly segregated patients from controls, independently of clinical features. PTA-PCR analysis on the validation cohort confirmed the deregulation of miR-224-5p, miR-206 and miR-653-5p. The combined receiver operating characteristic (ROC) curve analyses showed that such ci-miRNAs discriminate BS from HCs (and BS with active vs inactive disease), as well as BS from patients with SLE and GCA.The functional annotation analyses (FAAs) showed that the most enriched pathways affected by DE ci-miRNAs (ie, cell-matrix interaction, oxidative stress and blood coagulation) are related to thrombo-inflammatory mechanisms. Accordingly, the expression of the three ci-miRNAs from the validation cohort significantly correlated with leucocyte reactive oxygen species production and plasma lipid peroxidation. CONCLUSIONS: The ci-miRNA profile identified in this study may represent a novel, poorly invasive BS biomarker, while suggesting an epigenetic control of BS-related thrombo-inflammation.

Extracellular Signal-Regulated Kinase 5 Regulates the Malignant Phenotype of Cholangiocarcinoma Cells.

BACKGROUND AND AIMS: Cholangiocarcinoma (CCA) is characterized by high resistance to chemotherapy and poor prognosis. Several oncogenic pathways converge on activation of extracellular signal-regulated kinase 5 (ERK5), whose role in CCA has not been explored. The aim of this study was to investigate the role of ERK5 in the biology of CCA. APPROACH AND RESULTS: ERK5 expression was detected in two established (HuCCT-1 and CCLP-1) and two primary human intrahepatic CCA cell lines (iCCA58 and iCCA60). ERK5 phosphorylation was increased in CCA cells exposed to soluble mediators. In both HuCCT-1 and CCLP-1 cells, ERK5 was localized in the nucleus, and exposure to fetal bovine serum (FBS) further increased the amount of nuclear ERK5. In human CCA specimens, ERK5 mRNA expression was increased in tumor cells and positively correlated with portal invasion. ERK5 protein levels were significantly associated with tumor grade. Growth, migration, and invasion of CCA cells were decreased when ERK5 was silenced using specific short hairpin RNA (shRNA). The inhibitory effects on CCA cell proliferation, migration and invasion were recapitulated by treatment with small molecule inhibitors targeting ERK5. In addition, expression of the angiogenic factors VEGF and angiopoietin 1 was reduced after ERK5 silencing. Conditioned medium from ERK5-silenced cells had a lower ability to induce tube formation by human umbilical vein endothelial cells and to induce migration of myofibroblasts and monocytes/macrophages. In mice, subcutaneous injection of CCLP-1 cells silenced for ERK5 resulted in less frequent tumor development and smaller size of xenografts compared with cells transfected with nontargeting shRNA. CONCLUSIONS: ERK5 is a key mediator of growth and migration of CCA cells and supports a protumorigenic crosstalk between the tumor and the microenvironment.

The Transcriptional Landscape of BRAF Wild Type Metastatic Melanoma: A Pilot Study.

Melanoma is a relatively rare disease worldwide; nevertheless, it has a great relevance in some countries, such as in Europe. In order to shed some light upon the transcriptional profile of skin melanoma, we compared the gene expression of six independent tumours (all progressed towards metastatic disease and with wild type BRAF) to the expression profile of non-dysplastic melanocytes (considered as a healthy control) in a pilot study. Paraffin-embedded samples were manually micro-dissected to obtain enriched samples, and then, RNA was extracted and analysed through a microarray-based approach. An exhaustive bioinformatics analysis was performed to identify differentially expressed transcripts between the two groups, as well as enriched functional terms. Overall, 50 up- and 19 downregulated transcripts were found to be significantly changed in the tumour compared to the control tissue. Among the upregulated transcripts, the majority belonged to the immune response group and to the proteasome, while most of the downregulated genes were related to cytosolic ribosomes. A Gene Set Enrichment Analysis (GSEA), along with the RNA-Seq data retrieved from the TCGA/GTEx databases, confirmed the general trend of downregulation affecting cytoribosome proteins. In contrast, transcripts coding for mitoribosome proteins showed the opposite trend.

Locus Coeruleus Neurons' Firing Pattern Is Regulated by ERG Voltage-Gated K+ Channels.

Locus coeruleus (LC) neurons, with their extensive innervations throughout the brain, control a broad range of physiological processes. Several ion channels have been characterized in LC neurons that control intrinsic membrane properties and excitability. However, ERG (ether-à-go-go-related gene) K+ channels that are particularly important in setting neuronal firing rhythms and automaticity have not as yet been discovered in the LC. Moreover, the neurophysiological and pathophysiological roles of ERG channels in the brain remain unclear despite their expression in several structures. By performing immunohistochemical investigations, we found that ERG-1A, ERG-1B, ERG-2 and ERG-3 are highly expressed in the LC neurons of mice. To examine the functional role of ERG channels, current-clamp recordings were performed on mouse LC neurons in brain slices under visual control. ERG channel blockade by WAY-123,398, a class III anti-arrhythmic agent, increased the spontaneous firing activity and discharge irregularity of LC neurons. Here, we have shown the presence of distinct ERG channel subunits in the LC which play an imperative role in modulating neuronal discharge patterns. Thus, we propose that ERG channels are important players behind the changes in, and/or maintenance of, LC firing patterns that are implicated in the generation of different behaviors and in several disorders.

Prognostic role of hERG1 Potassium Channels in Neuroendocrine Tumours of the Ileum and Pancreas.

hERG1 potassium channels are widely expressed in human cancers of different origins, where they affect several key aspects of cellular behaviour. The present study was designed to evaluate the expression and clinical relevance of hERG1 protein in cancer tissues from patients suffering from neuroendocrine tumours (NETs) of ileal (iNETs) and pancreatic (pNETs) origin, with available clinicopathological history and follow-up. The study was carried out by immunohistochemistry with an anti-hERG1 monoclonal antibody. In a subset of samples, a different antibody directed against the hERG1/ß1 integrin complex was also used. The analysis showed for the first time that hERG1 is expressed in human NETs originating from either the ileum or the pancreas. hERG1 turned out to have a prognostic value in NETs, showing (i) a statistically significant positive impact on OS of patients affected by ileal NETs, regardless the TNM stage; (ii) a statistically significant positive impact on OS of patients affected by aggressive (TNM stage IV) disease, either ileal or pancreatic; (iii) a trend to a negative impact on OS of patients affected by less aggressive (TNM stage I-III) disease, either ileal or pancreatic. Moreover, in order to evaluate whether ERG1 was functionally expressed in a cellular model of pNET, the INS1E rat insulinoma cell line was used, and it emerged that blocking ERG1 with a specific inhibitor of the channel (E4031) turned out in a significant reduction in cell proliferation.

Mitochondrial oxidative metabolism contributes to a cancer stem cell phenotype in cholangiocarcinoma.

BACKGROUND & AIMS: Little is known about the metabolic regulation of cancer stem cells (CSCs) in cholangiocarcinoma (CCA). We analyzed whether mitochondrial-dependent metabolism and related signaling pathways contribute to stemness in CCA. METHODS: The stem-like subset was enriched by sphere culture (SPH) in human intrahepatic CCA cells (HUCCT1 and CCLP1) and compared to cells cultured in monolayer. Extracellular flux analysis was examined by Seahorse technology and high-resolution respirometry. In patients with CCA, expression of factors related to mitochondrial metabolism was analyzed for possible correlation with clinical parameters. RESULTS: Metabolic analyses revealed a more efficient respiratory phenotype in CCA-SPH than in monolayers, due to mitochondrial oxidative phosphorylation. CCA-SPH showed high mitochondrial membrane potential and elevated mitochondrial mass, and over-expressed peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α, a master regulator of mitochondrial biogenesis. Targeting mitochondrial complex I in CCA-SPH using metformin, or PGC-1α silencing or pharmacologic inhibition (SR-18292), impaired spherogenicity and expression of markers related to the CSC phenotype, pluripotency, and epithelial-mesenchymal transition. In mice with tumor xenografts generated by injection of CCA-SPH, administration of metformin or SR-18292 significantly reduced tumor growth and determined a phenotype more similar to tumors originated from cells grown in monolayer. In patients with CCA, expression of PGC-1α correlated with expression of mitochondrial complex II and of stem-like genes. Patients with higher PGC-1α expression by immunostaining had lower overall and progression-free survival, increased angioinvasion and faster recurrence. In GSEA analysis, patients with CCA and high levels of mitochondrial complex II had shorter overall survival and time to recurrence. CONCLUSIONS: The CCA stem-subset has a more efficient respiratory phenotype and depends on mitochondrial oxidative metabolism and PGC-1α to maintain CSC features. LAY SUMMARY: The growth of many cancers is sustained by a specific type of cells with more embryonic characteristics, termed 'cancer stem cells'. These cells have been described in cholangiocarcinoma, a type of liver cancer with poor prognosis and limited therapeutic approaches. We demonstrate that cancer stem cells in cholangiocarcinoma have different metabolic features, and use mitochondria, an organelle located within the cells, as the major source of energy. We also identify PGC-1α, a molecule which regulates the biology of mitochondria, as a possible new target to be explored for developing new treatments for cholangiocarcinoma.

Expression and purification of a novel single-chain diabody (scDb-hERG1/ß1) from Pichia pastoris transformants.

In the last decades, protein engineering has developed particularly in biotechnology and pharmaceutical field. In particular, the engineered antibody subclass has arisen. The single chain diabody format (scDb), conjugating small size with antigen specificity, offers versatility representing a gold standard for a variety of applications, spacing from research to diagnostics and therapy. Along with such advantages, comes the challenge of optimizing their production, improving expression systems, purification procedures and stability. All such parameters are detrimental for protein production in general and above all for recombinant antibody expression, which has to be fine-tuned, choosing a proper protein-expression host and adjusting expression protocols accordingly. In the present paper, we present data regarding the production and purification of a single chain diabody directed against the macromolecular complex hERG1/ß1 integrin. We focus on the expression of clones deriving from the transformation of Pichia pastoris yeast cells. In particular, we compare two different clones arose from two separate transformation processes, demonstrating that both are suitable for proper protein expression. Moreover, we have set up an expression protocol and compared the yields obtained using two purification machines: Akta Pure and Akta Start, with a positive outcome.

The combined activation of KCa3.1 and inhibition of Kv11.1/hERG1 currents contribute to overcome Cisplatin resistance in colorectal cancer cells.

BACKGROUND: Platinum-based drugs such as Cisplatin are commonly employed for cancer treatment. Despite an initial therapeutic response, Cisplatin treatment often results in the development of chemoresistance. To identify novel approaches to overcome Cisplatin resistance, we tested Cisplatin in combination with K+ channel modulators on colorectal cancer (CRC) cells. METHODS: The functional expression of Ca2+-activated (KCa3.1, also known as KCNN4) and voltage-dependent (Kv11.1, also known as KCNH2 or hERG1) K+ channels was determined in two CRC cell lines (HCT-116 and HCT-8) by molecular and electrophysiological techniques. Cisplatin and several K+ channel modulators were tested in vitro for their action on K+ currents, cell vitality, apoptosis, cell cycle, proliferation, intracellular signalling and Platinum uptake. These effects were also analysed in a mouse model mimicking Cisplatin resistance. RESULTS: Cisplatin-resistant CRC cells expressed higher levels of KCa3.1 and Kv11.1 channels, compared with Cisplatin-sensitive CRC cells. In resistant cells, KCa3.1 activators (SKA-31) and Kv11.1 inhibitors (E4031) had a synergistic action with Cisplatin in triggering apoptosis and inhibiting proliferation. The effect was maximal when KCa3.1 activation and Kv11.1 inhibition were combined. In fact, similar results were produced by Riluzole, which is able to both activate KCa3.1 and inhibit Kv11.1. Cisplatin uptake into resistant cells depended on KCa3.1 channel activity, as it was potentiated by KCa3.1 activators. Kv11.1 blockade led to increased KCa3.1 expression and thereby stimulated Cisplatin uptake. Finally, the combined administration of a KCa3.1 activator and a Kv11.1 inhibitor also overcame Cisplatin resistance in vivo. CONCLUSIONS: As Riluzole, an activator of KCa3.1 and inhibitor of Kv11.1 channels, is in clinical use, our results suggest that this compound may be useful in the clinic to improve Cisplatin efficacy and overcome Cisplatin resistance in CRC.

hERG1 channel expression associates with molecular subtypes and prognosis in breast cancer.

BACKGROUND: Breast cancer (BC) is the most frequent malignancy among females worldwide. Despite several efforts and improvements in early diagnosis and treatment, there are still tumors characterized by an aggressive behavior due to unfavorable biology, thus quite difficult to treat. In this view, searching for novel potential biomarkers is mandatory. Among them, in the recent years data have been gathered addressing ion channel as important players in oncology. METHODS: A retrospective pilot study was performed on 40 BC samples by means of immunohistochemistry in order to evaluate hERG1 potassium channels expression in BC. RESULTS: We provide evidence that hERG1 is expressed in all the BC samples analyzed. hERG1 expression was significantly associated with molecular subtype with the highest expression in Luminal A and the lowest in basal-like tumors (p = 0.001), tumor grading (the highest hERG1 expression in well-moderate differentiated tumors, p = 0.020), estrogen receptors (high hERG1 expression in ER-positive samples, p = 0.008) and Ki67 proliferative index (high hERG1 scoring in samples with low proliferative index, p = 0.038). Also, a p value close to significance was noticed for the association between hERG1 and HER2 expression (p = 0.079). At the survival analysis, patients with high hERG1 expression turned out to have a longer progression-free survival, although statistical significance was not reached (p = 0.195). The same trend was observed analyzing local relapse free-survival (LRFS) and metastases-free survival (MFS): patients with higher hERG1 scoring had longer LRFS and MFS (p = 0.124 and p = 0.071, respectively). CONCLUSIONS: The results of this pilot study provide the first evidence that the hERG1 protein is expressed in primary BC, and its expression associates with molecular subtype. hERG1 apparently behaves as a protective factor, since it contributes to identify a subset of patients with better outcome. Overall, these data suggest that hERG1 might be an additional tool for the management of BC, nevertheless further investigations are warranted to better clarify hERG1 role and clinical usefulness in BC.

Engineering l-asparaginase for spontaneous formation of calcium phosphate bioinspired microreactors.

Active bioinspired materials are appealing biotechnological targets, and their study is gaining momentum. These materials, which comprise of an inorganic matrix and one or more biomolecules, are extremely variable and therefore may result difficult to characterize in their intimate structure. In this work we have prepared a hydroxyapatite-l-asparaginase composite, with the perspective of using it in acute leukemia treatment. We demonstrate that the use of electron microscopy and powder X-ray diffraction, combined with the atomic-resolution information coming from solid-state NMR, allows us to understand the topology of the material and how the different components interplay to obtain an active composite.

Ion channel expression as promising cancer biomarker.

Cancer is a disease with marked heterogeneity in both response to therapy and survival. Clinical and histopathological characteristics have long determined prognosis and therapy. The introduction of molecular diagnostics has heralded an explosion in new prognostic factors. Overall, histopathology, immunohistochemistry and molecular biology techniques have described important new prognostic subgroups in the different cancer categories. Ion channels and transporters (ICT) are a new class of membrane proteins which are aberrantly expressed in several types of human cancers. Besides regulating different aspect of cancer cell behavior, ICT can now represent novel cancer biomarkers. A summary of the data obtained so far and relative to breast, prostate, lung, colorectal, esophagus, pancreatic and gastric cancers are reported. Special emphasis is given to those studies aimed at relating specific ICT or a peculiar ICT profile with current diagnostic methods. Overall, we are close to exploit ICTs for diagnostic, prognostic or predictive purposes in cancer. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Cisplatin and its dibromido analogue: a comparison of chemical and biological profiles.

The dibromido analogue of cisplatin, cis-PtBr2(NH3)2 (cisPtBr2 hereafter), has been prepared and characterised. Its solution behaviour in standard phosphate buffer, at pH 7.4, was investigated spectrophotometrically and found to reproduce quite closely that of cisplatin; indeed, progressive sequential release of the two halide ligands typically occurs as in the case of cisplatin, with a roughly similar kinetics. Afterward, patterns of reactivity toward model proteins and standard ctDNA were explored and the nature of the resulting interactions elucidated. The antiproliferative properties were then evaluated in four representative cancer cell lines, namely A549 (human lung cancer), HCT116 (human colon cancer), IGROV-1 (human ovarian cancer) and FLG 29.1 (human acute myeloid leukaemia). Cytotoxic properties in line with those of cisplatin were highlighted. From these studies an overall chemical and biological profile emerges for cisPtBr2 closely matching that of cisplatin; the few slight, but meaningful differences that were underscored might be advantageously exploited for clinical application.

Novel perspectives in cancer therapy: Targeting ion channels.

By controlling ion fluxes at multiple time scales, ion channels shape rapid cell signals, such as action potential and synaptic transmission, as well as much slower processes, such as mitosis and cell migration. As is currently increasingly recognized, a variety of channel types are involved in cancer hallmarks, and regulate specific stages of neoplastic progression. Long-term in vitro work has established that inhibition of these ion channels impairs the growth of cancer cells. Recently, these studies have been followed up in vivo, hence revealing that ion channels constitute promising pharmacological targets in oncology. The channel proteins can be often accessed from the extracellular milieu, which allows use of lower drug doses and decrease untoward toxicity. However, because of the central physiological roles exerted by ion channels in excitable cells, other types of side effects may arise, the gravest of which is cardiac arrhythmia. A paradigmatic case is offered by Kv11.1 (hERG1) channels. HERG1 blockers attenuate the progression of both hematologic malignancies and solid tumors, but may also lead to the lengthening of the electrocardiographic QT interval, thus predisposing the patient to ventricular arrhythmias. These side effects can be avoided by specifically inhibiting the channel isoforms which are highly expressed in certain tumors, such as Kv11.1B and the neonatal forms of voltage-gated Na(+) channels. Preclinical studies are also being explored in breast and prostate cancer (targeting voltage-gated Na(+) channels), and gliomas (targeting CLC-3). Overall, the possible approaches to improve the efficacy and safety of ion channel targeting in oncology include: (1) the development of specific inhibitors for the channel subtypes expressed in specific tumors; (2) drug delivery into the tumor by using antibodies or nanotechnology-based approaches; (3) combination regimen therapy and (4) blocking specific conformational states of the ion channel. We believe that expanding this relatively neglected field of oncology research might lead to unforeseen therapeutic benefits for cancer patients.

New pyrimido-indole compound CD-160130 preferentially inhibits the KV11.1B isoform and produces antileukemic effects without cardiotoxicity.

KV11.1 (hERG1) channels are often overexpressed in human cancers. In leukemias, KV11.1 regulates pro-survival signals that promote resistance to chemotherapy, raising the possibility that inhibitors of KV11.1 could be therapeutically beneficial. However, because of the role of KV11.1 in cardiac repolarization, blocking these channels may cause cardiac arrhythmias. We show that CD-160130, a novel pyrimido-indole compound, blocks KV11.1 channels with a higher efficacy for the KV11.1 isoform B, in which the IC50 (1.8 µM) was approximately 10-fold lower than observed in KV11.1 isoform A. At this concentration, CD-160130 also had minor effects on Kir2.1, KV 1.3, Kv1.5, and KCa3.1. In vitro, CD-160130 induced leukemia cell apoptosis, and could overcome bone marrow mesenchymal stromal cell (MSC)-induced chemoresistance. This effect was caused by interference with the survival signaling pathways triggered by MSCs. In vivo, CD-160130 produced an antileukemic activity, stronger than that caused by cytarabine. Consistent with its atypical target specificity, CD-160130 did not bind to the main binding site of the arrhythmogenic KV11.1 blockers (the Phe656 pore residue). Importantly, in guinea pigs CD-160130 produced neither alteration of the cardiac action potential shape in dissociated cardiomyocytes nor any lengthening of the QT interval in vivo. Moreover, CD-160130 had no myelotoxicity on human bone marrow-derived cells. Therefore, CD-160130 is a promising first-in-class compound to attempt oncologic therapy without cardiotoxicity, based on targeting KV11.1. Because leukemia and cardiac cells tend to express different ratios of the A and B KV11.1 isoforms, the pharmacological properties of CD-160130 may depend, at least in part, on isoform specificity.

Searching for protein binding sites from Molecular Dynamics simulations and paramagnetic fragment-based NMR studies.

Hotspot delineation on protein surfaces represents a fundamental step for targeting protein-protein interfaces. Disruptors of protein-protein interactions can be designed provided that the sterical features of binding pockets, including the transient ones, can be defined. Molecular Dynamics, MD, simulations have been used as a reliable framework for identifying transient pocket openings on the protein surface. Accessible surface area and intramolecular H-bond involvement of protein backbone amides are proposed as descriptors for characterizing binding pocket occurrence and evolution along MD trajectories. TEMPOL induced paramagnetic perturbations on (1)H-(15)N HSQC signals of protein backbone amides have been analyzed as a fragment-based search for surface hotspots, in order to validate MD predicted pockets. This procedure has been applied to CXCL12, a small chemokine responsible for tumor progression and proliferation. From combined analysis of MD data and paramagnetic profiles, two CXCL12 sites suitable for the binding of small molecules were identified. One of these sites is the already well characterized CXCL12 region involved in the binding to CXCR4 receptor. The other one is a transient pocket predicted by Molecular Dynamics simulations, which could not be observed from static analysis of CXCL12 PDB structures. The present results indicate how TEMPOL, instrumental in identifying this transient pocket, can be a powerful tool to delineate minor conformations which can be highly relevant in dynamic discovery of antitumoral drugs.

Lymphatic endothelial progenitor cells and vascular endothelial growth factor-C in spondyloarthritis and Crohn's disease: two overlapping diseases?

OBJECTIVES: The role of the lymphatic system in the connection between spondyloarthritis (SpA) and Crohn's disease (CD) remains yet to be elucidated. The aim of the present study was to investigate the circulating levels of lymphatic endothelial progenitor cells (LEPCs) and vascular endothelial growth factor-C (VEGF-C) and their possible correlation with clinical parameters in SpA, SpA associated with CD (SC), and CD. METHODS: Peripheral blood samples from SpA (n=36), SC (n=20) and CD (n=28) patients and 20 age- and sex-matched healthy controls were collected and used for quantification of circulating LEPCs and VEGF-C. LEPCs were identified by fluorescence-activated cell sorting using FITC-CD34, APC-CD133 and PE-VEGFR-3 antibodies. Serum levels of VEGF-C were measured by enzyme-linked immunosorbent assay. The possible correlations between disease duration (< or >10 years; < or >20 years) and clinical activity (BASDAI for SpA or CDAI for CD) and LEPC counts and VEGF-C levels were analysed. RESULTS: Circulating LEPC levels were significantly increased in SpA (p=0.0006) and SC (p=0.0058) patients compared with controls. In CD patients, LEPC counts negatively correlated with disease duration, with lower levels in longstanding disease (>20 years, p=0.018), but were not different from controls. No significant difference in VEGF-C levels was found in SpA, SC and CD compared with controls. Both LEPC and VEGF-C levels were independent of BASDAI and CDAI. CONCLUSIONS: On the basis of our observations, an active mobilisation of lymphatic endothelial cell precursors was observed only for spondylitis involvement.

Time resolved SAXS to study the complexation of siRNA with cationic micelles of divalent surfactants.

The complexation of siRNA (small interfering RNA) with cationic micelles was studied using time dependent synchrotron SAXS. Micelles were formed by two types of divalent cationic surfactants, i.e. Gemini bis(quaternary ammonium) bromide with variable spacer length (12-3-12, 12-6-12, 12-12-12) and a weak electrolyte surfactant (SH14) with triazine head. Immediately after mixing (t < 50 ms), new large aggregates appeared in solution and the scattering intensity at low q increased. Concomitantly, the presence of a quasi-Bragg peak at q ∼ 1.5 nm(-1) indicated core structuring within the complexes. We hypothesize that siRNA and micelles are alternately arranged into "sandwiches", forming domains with internal structural coherence. The process of complex reorganization followed a first-order kinetics and was completed in less than about 5 minutes, after which a steady state was reached. Aggregates containing Geminis were compact globular structures whose gyration radii Rg depended on the spacer length and were in the order of 7-27 nm. Complexes containing SH14 (Rg = 14-16 nm) were less ordered and possessed a looser internal arrangement. The obtained data, joint with previous structural investigation using Dynamic Light Scattering, Zeta Potential and Small Angle Neutron Scattering, are encouraging evidence for using these systems in biological trials. In fact we showed that transfection agents can be obtained by simply mixing a micelle solution of the cationic surfactant and a siRNA solution, both of which are easily prepared and stable.